Alternator v. no alternator - 10% gain @ 70 km/h

[MetroMPG]

FYI, other GS threads that talk about alternators are:
Alterpower (shutting off alternator)

(http://www.gassavers.org/showthread.php?t=334&highlight=alternator)
Does the Civic VX have a unique alternator?

(http://www.gassavers.org/showthread.php?t=783&highlight=alternator)
Power (accessory type) consumption and FE

(http://www.gassavers.org/showthread.php?t=876&highlight=alternator)
Solar/plug-in 12V system, alternator optional (http://www.gassavers.org/showthread.php?t=330&highlight=alternator)

[95metro]

Anticipate any difficulties switching belts on the roadside? A-B-A testing is going to be a pain...good luck! Us yocals without instant mpg readouts really, really, REALLY appreciate the effort!

[SVOboy]

95Metro, get yourself a superMID, it's the best. Every day has become a personal FE challenge for myself, and I find that I'm really pushing it in order to do my very best and paying attention to minute details much much more.

Darin, you're the beast! I'm starting to understand the concept much better, :p. In any case, I will try and do some civic testing for you when I get my MID stuff ironed out. I'm hoping to have testing starting (with numbers, but fake ones) after I fill up, but who knows, my gramma will be in towne for graduation, but we'll see!

Good luck!

[95metro]

95Metro, get yourself a superMID, it's the best.

*sigh* I'd love to, but I have far too many demands on my pocketbook already. I've got other repairs on the car that I should get done before I purchase a MID. I'm having a hard enough time scraping together the money for my exhaust.

[krousdb]

95Metro, get yourself a superMID, it's the best. Every day has become a personal FE challenge for myself, and I find that I'm really pushing it in order to do my very best and paying attention to minute details much much more.

Details man! Details! Post something in the daily updates thread.

[MetroMPG]

Anticipate any difficulties switching belts on the roadside?

No, it's away from the hot stuff, and I only need to adjust one bolt on the alternator to get the OEM belt on/off. The home made bypass belt is basically a big rubber band - pretty easy to get on/off. (v.2 has been in service for about 275 km / 170 miles now without self destructing.)

95Metro, get yourself a superMID, it's the best.

I agree. Driving without FE instrumentation is like drag racing without seeing your 1/4 mile time at the end of the run, or like lapping and not knowing your lap times... until a week or so later when they come in the mail or something.

[Randy]

Back when I was messing with my alternator, I measured the electrical loads of various things (using a shunt on the alternator output). Not a super-exact test, but it should give a ballpark for smaller cars.

I tested at both voltage settings of the alt, where 14.4 is typical alt voltage, and 12.7 is similar to a fully charged battery. The idle current is subtracted out of the other settings.

Idle: 128w @ 14.4v, 89w @ 12.7v
Rev up to 3500 rpm: +35w, (not tested)
Heater fan setting 1: 55w, 38w
Setting 2: 98, 67
Setting 3: 141, 99
Setting 4: 189, 135
Marker lights: 95, 71
Full lights: 240, 179
A/C (heater fan subtracted, but including condenser fan): 163, 114
Defroster: 104, 77
Wipers 1: 48, 38
Wipers 2: 76, 64
Radiator fan: 144, 83

[SVOboy]

Does that mean that a/c is less of a drag than full blast non-cooled air? Of course you need to add the fan to the a/c, but still, do you get me?

[JanGeo]

The AC will drag the engine directly and not present an electrical load except for any clutch power on the pulley and the blower fan. Nice measurements on the car electrical loads!! How about the car computer, fuel pump and ignition loads??

[MetroMPG]

I have some results.

But first: Randy, great data. Thanks for posting it. What car/engine is it from?

Preliminary results (I'll do a proper write up later with charts & margin of error etc. and post at the top of the thread):

Speed 70 km/h / 43.5 mph

A: alternator belt ON - 71.16 mpg (US) - avg of 3 bi-dir runs (6 one-way runs)

B: alternator belt OFF - 78.08 mpg (US) - avg of 3 bi-dir runs

A: alternator belt ON - 70.2 mpg (US) - avg of 2 bi-dir runs

Notes:
the last A runs were made after reinstalling the belt and driving for 10 minutes to replace energy taken out of the batt from the B run (simply re-installing the belt and doing the runs would have skewed it as the alternator ran at a higher load recharging things).
electrical loads, all runs: cruise control, parking lights
for half of the last A runs: same, plus headlights on (ran out of daylight)So! That's about double the effect I was guesstimating. I'm expecting a run on deep cycle batteries now...

I wonder if the effect will be different for larger engines, since the alternator is a proportionately smaller part of engine output at a given speed. Discuss. :)

[budomove]

I have a 91 civic hatch std (stock).

If I were to remove the alternator belt, how long would it take to drain an average healthy battery?

How often would I need to reconnect the alternator belt, or charge the batery?

I would be willing to run a test if it weren't to big of a pain.

I guess I could just permanently leave the belt off, and use a plug in charger...assuming the battery stays charged long enough for this mod to be a practical option.

[MetroMPG]

If I were to remove the alternator belt, how long would it take to drain an average healthy battery?
Depends on your battery, your electrical loads, and temperatures (batteries don't like very hot or very cold - performance is relative). Only way to tell is to monitor it.

I drove 50 km with *minimal* electrical loads on a pleasantly warm day and calculated I used about 25% of my battery's capacity. see reply #24:
http://www.gassavers.org/showthread.php?p=11807#post11807

How often would I need to reconnect the alternator belt, or charge the batery?
See above :)

Also note that just reconnecting the belt to charge your battery erases the benefit of driving with the belt off. You may actually get WORSE mileage if you do that. The only advantage to be gained is if you recharge your battery from an external source (I've been using a solar panel).

Also note: the fastest way to destroy a starting battery is to discharge it deeply & repeatedly. You really need a deep-cycle battery to do this mod properly.

[budomove]

Metro, This solar panel, could it be permanently mounted on the car?

How big is it, $?

[Compaq888]

where can I get a solar panel good enough so I can remove my alternator?

[budomove]

http://www.batterystuff.com/solar-chargers/

[budomove]

check out the one with the cigarette lighter option. You could leave it inside the car to constantly charge, right guys? http://www.siliconsolar.com/automotive-solar-battery-chargers.php

[MetroMPG]

If you drive a normal amount, it will cost you a lot of money to get enough panels to keep your battery topped up

[budomove]

http://www.siliconsolar.com/shop/catalog/Solar-Car-Battery-Charger-p-139.html
"Connect to battery when the car is parked, Simply Built-in LED indicator will light up during charging plugs into cigarette lighter, Suction cups for easy mounting"


Weight: 1lb
Dimensions: 12" x 4" x .75"
13v @ 200-250mA $24.95 !!!!!!!!!

*But can it be used while driving, or can any of them? That would allow us

to drive as long as we want, a definite plus!

[Compaq888]

too bad regular cars don't come with regenarative braking. That way it can charge the battery and run all accesories. it would probably improve 3-5mpg.

[budomove]

[quote=budomove13v @ 200-250mA[/quote]



So this would be really bad, huh?

Looks like less than a 1/4 amp, right?

Can you leave them hooked up while you drive?

If so, how many amps you think you'd need under the most stressful driving to ensure the battery didn't die?

This would be with a deep cycle battery of course.

How much do they cost?

[MetroMPG]

Yup. A 200 mA panel is pretty useless for a car.

Keep in mind, your alternator is probably rated for roughly 55A max output. And it likely runs at around 5-10A in normal driving (light-moderate electrical load).

Meaning, you'd need 5-10 of my 1x3 ft. 1A panels, aimed perfectly at the sun, to provide as much power as the car is taking from the battery while driving. :eek:

You can leave a solar panel connected while you drive.

Deep cycle batteries are a little bit more expensive than starting batteries.

[katman]

Harbor Freight sells them!

[Randy]

The readings were for my 94 Civic EX. It takes a lot of power to run the thing: 90 watts minimal just idling. All the stuff on, like in the winter, takes more than 700 watts. There's no way a portable panel could keep up with idling, it would be a good load even for a battery charger.

However a full size battery would be enough for maybe an hour, though a starter battery will fall apart after a few times doing this, especially if you try and trickle-charge it. A big deep-cycle battery and a good charger is a better bet.

[Ryland]

I am alwas impressed with the markup they put on solor battery maintaners, if you wanted to buy solor panals like you might put on your house, you could exspect to pay around $4-5 a watt if you are buying a number of panels, $24.95 for a quarter watt panal is... $99.80 per watt or 19 times what the panal could cost.
Randy said that he figured 90 watts just to idle the car, correct? and you want to produce more then you use, so round it up to a nice round number like 100 watts to run the car, and charge the battery a little bit from it being cloudy yesterday, of course you don't want to over charge your battery, so you want a charge controler too, and then all the wire, and mounting, and I'm guessing it is going to cost around $500-600 to remove your alternator and replace it with solar, of course the solar panals are going to outlast the rest of your car, so it's a pretty solid investment, but you are most likely going to want to also invest in things like a small alternator that you can kick in at night, and cloudy days, and LED lights all around.

[Matt Timion]

I think the real solution here is find a way to create the turbo-charger alternators.

I've never played with a turbo before, but how much work would it be to gut the internals and hook up an alternator to spin powered by the exhaust gas?

You guys know the device I'm talking about. Maybe it's time to get creative and make our own.

[Compaq888]

I think the real solution here is find a way to create the turbo-charger alternators.

I've never played with a turbo before, but how much work would it be to gut the internals and hook up an alternator to spin powered by the exhaust gas?

You guys know the device I'm talking about. Maybe it's time to get creative and make our own.

BMW is way ahead of you. They already have a prototype and they said they will start putting it in production cars in 2012

[Matt Timion]

BMW is way ahead of you. They already have a prototype and they said they will start putting it in production cars in 2012

I wouldn't call 2012 way ahead of me. This is why I said we should make our own instead of waiting.

[95metro]

I think the real solution here is find a way to create the turbo-charger alternators.

I agree Matt. After seeing one of those I was pretty convinced that it's the closest thing to a "perfect" solution.

The turbos that are probably the most plentiful would be from Dodge 2.2 and 2.5 liter turbo cars. Find a junker and strip the turbo from it. The major difficulty would be getting it mounted to the exhaust manifold. I've been considering it using the manifold and turbo from a Turbo Sprint/Firefly, but it's going to be a while before it happens (like next year...or the next after that).

The added benefit of some mild turbo boost (unless the alternator steals all the energy) could improve highway mpg as well.

[Matt Timion]

I agree Matt. After seeing one of those I was pretty convinced that it's the closest thing to a "perfect" solution.

The turbos that are probably the most plentiful would be from Dodge 2.2 and 2.5 liter turbo cars. Find a junker and strip the turbo from it. The major difficulty would be getting it mounted to the exhaust manifold. I've been considering it using the manifold and turbo from a Turbo Sprint/Firefly, but it's going to be a while before it happens (like next year...or the next after that).

The added benefit of some mild turbo boost (unless the alternator steals all the energy) could improve highway mpg as well.

Well, I don't think what I have in mind would work as both a turbo AND an alternator.

i don't want to actually turbo my vehicle because it would require lots and lots of money and work. There is still no definate proof that doing so will actually help fuel economy either.

Anyway, this is what I'm talking about:

http://www.greencarcongress.com/2005/09/tigers_exhaust_.html

[95metro]

There is still no definate proof that doing so will actually help fuel economy either.

Yeah, that Tiger exhaust is what I read as well. And I agree about "no definite proof" regarding forced induction and FE - my statement was simply based on hearsay regarding the Turbo Swift-clones getting better FE at highway speeds than the NA clones.

It's something I'd like to try. The generator would be worth it on its own. If the turbo did help FE that would just be a major bonus.

[MetroMPG]

I wonder about backpressure and how much it would affect FE to generate the equivalent energy of a belt-driven alternator. There's no free lunch!

[95metro]

True, there's energy loss both ways, isn't there?

[Matt Timion]

True, there's energy loss both ways, isn't there?

Agreed... there is energy loss either way. I guess it's just a matter of picking the one with the least amount of energy loss.

Maybe this is something to look into for the future... or I can just wait until 2012.

[Ryland]

a friends brother works at a shop that apparently has a "scrap bin" of turbos, I asked him a while back to find me the smallest turbo possible, just the other day he said it was in and that I coudl pick it up, not sure how small it really is, but it might work well for a project like this, he also picked up another turbo with the 5" exuast intake port to use for another turbine engine project, I can't wait to see both of them.

and VW's come with solar panals in them to keep the battery fully charge in shipping, apparently it's "to costly" to send them back to use again, a fully charged battery will last longer.

[Compaq888]

Me don't care, if you can take out the alternator then me care. Alternator is dead weight.

[SVOboy]

Well if you're not using it you can take it out. The starter is more of a dead weight than the alternator anyway.

[Compaq888]

Well if you're not using it you can take it out. The starter is more of a dead weight than the alternator anyway.

I just want something so I could take out my alternator completly. I don't use the radio. I only use the lights, turn signals, cruise control and very rarely the air conditioner. I've even put LED's to reduce the load on my electrical system.

[SVOboy]

Then take it out and hook up a solar panel to charge the battery, :p

[Compaq888]

Then take it out and hook up a solar panel to charge the battery, :p

So there is a solar panel good enough where I could take out the alternator completly???

[Compaq888]

ok I found out that the belt that is on the alternator also shares the power steering pump and the water pump pulley. So I can't take the alternator out. So what can I do to increase my mpg without pulling out the alternator???

Maybe get a solar panel that will make the car use less my alternator or how does it work?

[Matt Timion]

ok I found out that the belt that is on the alternator also shares the power steering pump and the water pump pulley. So I can't take the alternator out. So what can I do to increase my mpg without pulling out the alternator???

Maybe get a solar panel that will make the car use less my alternator or how does it work?

You can get a shorter belt.

I think the only way to really go without an alternator is to have a number of deep cycle batteries in the trunk. Of course each of these will weight around 30lbs.

I think energy is better suited in finding an alternative to an alternator, like the turbo alternator idea.

[SVOboy]

I hate those big serpertine belts, but thay prolly make more sense. I have 1 belt for 1 task, though the only task that really exists is a/c and alternator.

[red91sit]

I'm liking this turbo alernator idea, We have restrictions in our eshaust either way to reduce noise output, a turbo is slightly less efficient than a regular muffler, but if it's doing work... The only problem I see is the exhaust is VERY hot...

[BEN_EJ8]

I wouldn't call 2012 way ahead of me. This is why I said we should make our own instead of waiting.

If you want, I have a T3 turbo that should be rebuilt, but I doubt Ill ever get around to doing it. You or anybody on this forum could have it for dirt cheap to experiment with. I think it would be awesome to create an exhaust powered alternator and save 10% of gas :thumbup:

[gashog]

Has anybody copiled a list of all the things that they tried showing the gains/loss, good and bad of each try, and lessens learned with each try???
that would be a great building tool for everybody passing out the information

[Coyote X]

One thing I am curious about is if disconnecting the alternator without removing the belt would show the same gain in mileage. The alternator isn't really that heavy and most likely would not be much drag if it had the power disconnected from it.

The advantage would be you could put a switch on the dash so the alternator charges the engine when you need it, but can turn it off for the most part. Like if you had to go somewhere on a long trip and would otherwise not be able to make it without the alt.

Taking this discussion in a strange direction. Maybe make a regenerative braking system by epoxying a bunch of super magnets to the brake drum/rotors and getting a coil near it so when you want to slow down you connect the coils through a bridge rectifier to your battery so it can help make up for the missing alternator. I think the extra weight of gluing 10 neodymium magnets to each rotor and a series of probably 6-8 coils on the backing plate would not be bad, maybe 10lbs total for all 4 wheels. It might be able to get 10-40 amps of current when the coils are connected. The noise generated from the coils when they are on would definately kill your radio reception though. This could be wired to a button or 4 so when you want to slow down faster than normal coasting you hit as many as you need to slow down with. An alternate way of activating them would be raise your brake pedal a half inch or so and set it so the extra travel trips the switches in sequence so you could use your brake pedal lightly to slow down/regen braking and if you need real brakes just push it farther.

I know, I know, I'm nuts but at least I sound like I know what I am talking about :)

[onegammyleg]

Hi Coyote X

You could use regen braking , and do it a much simpler way.(an alt wont provide much braking effect)
By placing a pulley on a driveshaft you can run an alternator easily.
They do this on rear drive prop shafts in RWD hot rods when they want the alt out of the engine bay.
They put them down near the diff's and run a small belt off the propellor shaft diff flange.
Works fine , but the alt is in a more hostile envornment (no bush bashing) so they can get damaged a little easier.
But assuming you have a FWD car the alt can be mostly still in the engine bay , nice and safe.
You can also switch the alt on and off when required manualy , but if you had it switched by a vacuum switch it could be set to charge only when idling , of course no charge when your sitting still , but there would be when your coasting up to a stop light for example.

During the day not much charge time would be needed.

Overall , probably not much benifit over having it driven off the engine and switched in this manner tho.

[AlexK]

Hey guys I have an idea. Are you familiar with Peltier junctions? They are usually used as thermoelectric coolers for computers and 12V coolers. When you pass a current through it, one side absorbs heat (gets cold) and the other side rejects heat (gets hot). Well they also work in reverse... if you heat one side and cool the other they generate electricity. You could attach one to the underside of your catalytic converter and attach a heat sink to the cold side which would be exposed to the flowing air under the vehicle. I know they are not very efficient as heat pumps, so as heat generators they are probably not good either, but if the heat is free any recovery would be good. I will do some research on efficiencies and report back here.

[AlexK]

The Peltier idea would work but it would be very expensive and you would need a lot of Peltier modules. This one: http://www.tellurex.com/power_modules/p219.html
Generates only 5.7W max and it costs $43. It is about the same as photovoltaics per watt but only works while you drive.

[Silveredwings]

The Peltier idea would work but it would be very expensive and you would need a lot of Peltier modules. This one: http://www.tellurex.com/power_modules/p219.html
Generates only 5.7W max and it costs $43.

They're 4.8V at 1.2A so you'd need 3 in series to get 14.4V (good enough to charge a car battery) at about 17W for $131.85, which might be enough power given that it can run continously*.

If you put 3 of those strings in parallel, you'd get 51W for $395.55, with 4 you'd get 68W for $527.40. I think that's comparable to a new alternator, (though I haven't priced one at a dealer lately) but that may be overkill.

It is about the same as photovoltaics per watt but only works while you drive.

*Well, to continue the photovoltaics analogy, PVs work whenever light hits them, Peltier junction devices should work whenever there is a temperature differential across them. So, if one side is heat-sinked, and the other side is still hot from the engine block, they should still work while the engine is off.

[Brock]

First you guys are great. I have a 2003 VW diesel TDI and have been messing with the alternator and most people over on the TDI forums think I am nuts. I have found I get about a 5-7% increase in mileage with the alternator disabled. I leave the alt in there and just pull the main fuse so it basically sees’s no load. I am sure if I removed the alt or belt it would help a bit but if my wife takes the car to work I can just pop the fuse back and everything is back to normal.

A couple of things I have found out. The car once warm pulls about 100w or 8 amps. Having a solar array on the house solar is not really an option.

The car will "throw codes" because it sees something is wrong. So I had to find a way to keep the main battery topped off.

When I start the car it runs glow plugs and then coolant plugs (even in summer) until the coolant temp hits 120F. These glow plugs and then coolant plugs use 80 amps and 60 amps respectively. So again I needed to keep the main battery charged.

So what I did was took some parts I had laying around, 6 6v deep cycle batteries (golf cart) put two of them in series behind the passenger seat. I ran that in turn to a 1500w inverter which in turn feeds an iota DLS 55 amp charger set at 14.4v. The voltage will slowly drop until the coolant heaters shut off then quickly come up to 13.8v. I haven’t thrown a code since I tried this setup.

I originally tried just paralleling the batteries but the voltage under those loads would just drop too far, usually about 12.4v and the car didn't like it.

But getting back to my testing. I ran a set route, 3 miles there and back 6 times, 3 each way. On my test runs I got 87 mpg with the alt on and 92 mpg (according to scangauge) with the alt fuse pulled about 5% better. I ran a whole tank last spring and saw about a 5% improvement on the entire tank as well.

[MetroMPG]

Nice work, man!

It's amazing to think that the fuel economy improvement from grid-charging the battery and not running the alternator offsets the FE hit of the added battery weight.

Just 10 minutes ago, I came in (from a de-belted alternator local mostly pulse & glide trip - 104 mpg), and thought to myself: "I need to add some extra batteries for longer trips."

Just out of curiousity, why did you have floodies laying about? You either have a cart, or you're an EV builder...

[Brock]

LOL, close they are from my last battery bank from my solar PV system. My old battery bank had 8 Trojan T125's, my new bank is 8 AGMs for a total of 2000 A/H at 12v or 24kw total.

Oh no doubt the electricity is cheaper then the fuel burnt. Especially since I make some of it, and I charge off peak when my electricity rates are 1/2 the normal rate.

[kickflipjr]

First you guys are great. I have a 2003 VW diesel TDI and have been messing with the alternator and most people over on the TDI forums think I am nuts. I have found I get about a 5-7% increase in mileage with the alternator disabled. I leave the alt in there and just pull the main fuse so it basically sees’s no load. I am sure if I removed the alt or belt it would help a bit but if my wife takes the car to work I can just pop the fuse back and everything is back to normal.

A couple of things I have found out. The car once warm pulls about 100w or 8 amps. Having a solar array on the house solar is not really an option.

The car will "throw codes" because it sees something is wrong. So I had to find a way to keep the main battery topped off.

When I start the car it runs glow plugs and then coolant plugs (even in summer) until the coolant temp hits 120F. These glow plugs and then coolant plugs use 80 amps and 60 amps respectively. So again I needed to keep the main battery charged.

So what I did was took some parts I had laying around, 6 6v deep cycle batteries (golf cart) put them in series behind the passenger seat. I ran that in turn to a 1500w inverter which in turn feeds an iota DLS 55 amp charger set at 14.4v. The voltage will slowly drop until the coolant heaters shut off then quickly come up to 13.8v. I haven’t thrown a code since I tried this setup.

I originally tried just paralleling the batteries but the voltage under those loads would just drop too far, usually about 12.4v and the car didn't like it.

But getting back to my testing. I ran a set route, 3 miles there and back 6 times, 3 each way. On my test runs I got 87 mpg with the alt on and 92 mpg (according to scangauge) with the alt fuse pulled about 5% better. I ran a whole tank last spring and saw about a 5% improvement on the entire tank as well.


We have the makings a MPG beast here!

[rh77]

LOL, close they are from my last battery bank from my solar PV system. My old battery bank had 8 Trojan T125's, my new bank is 8 AGMs for a total of 2000 A/H at 12v or 24kw total.

What a great idea!

So, did the added weight effect drivability and stress the rear suspension? Also, do you know the approximate weight and cost if someone where to set up something similar -- perhaps a write-up?

RH77

[MetroMPG]

You guys basically made plug-in hybrids.

GM might say that, but I wouldn't. GM called its full-size pickups with autostop, an extra battery & an inverter for running power tools "hybrids". Silly marketing.

Doesn't a hybrid have to provide motive power from an electric motor to be a hybrid? Have to draw the line somewhere.

If you forget to push the clutch pedal in when you start a regular car and it moves via the starter, is that a hybrid? :D

[MetroMPG]

So, did the added weight effect drivability and stress the rear suspension? Also, do you know the approximate weight and cost if someone where to set up something similar -- perhaps a write-up?

The 6 batteries (even if 50 lbs each) would still have the car within its weight limits.

[rh77]

The 6 batteries (even if 50 lbs each) would still have the car within its weight limits .. If I'm saving 10% by running without the alt, then my fuel bill over the past year would have been reduced by roughly $34 over 8,700 km, or 0.39 cents/km. (And that's at higher CDN fuel prices.)

That's 300-pounds of extra weight, which I would say could account for a reduction in that 10% savings.

The question that next needs to be addressed is the range. Since the Diesel engine doesn't have a distributor, spark plugs, etc., then a battery isn't needed to run the engine. On a gasser, I'm thinking that the ignition system would drain the batts more quickly. I was also thinking about fewer batts for a short-trip commuter, but for a gasser, that might not be possible.

RH77

[MetroMPG]

The diesel may have a higher electrical overhead for the fuel pump, though, since they're high-pressure units. I don't really know for sure though. Just a guess.

[rh77]

The diesel may have a higher electrical overhead for the fuel pump, though, since they're high-pressure units. I don't really know for sure though. Just a guess.

The only frame of reference I have is a personal experience: driving an E-350 Diesel Ambulance back from a 100-mile round-trip transport. The charge cable to the battery busted loose (unknowingly at the time). Meanwhile, the digital electrical charge display was dropping like a rock. We were able to drive it for a ways, but it was storming and raining too hard to see (no wipers or headlights and tree limbs in the road), so we pulled into a gas station and had it towed back to base.

I think the alternator keeps things going -- in this case it was a heavy-duty alt.

RH77

[JanGeo]

I thought the fuel pump in a diesel is mechanical driven on the engine (injector pump) and it draws the fuel from the tank. Thus no power required except for the control of the injectors via a ECU?

It sounds like the best solution is still solar panels on the roof to lighten the alternator load when driving in bright sunlight and then the cost of the solar panels comes into play but at lease they will last the life of the vehicle and not require additional expendature. Plus on a bright day you can crank up the radio and use the excess energy!

[MetroMPG]

Note: split the discussion of weight into its own thread, because there's some good info in the weight thread deserving its own spotlight:

"Effect of weight on FE: estimates from online sources"
http://www.gassavers.org/showthread.php?t=2003

Note: I'm not saying the effect of extra batteries in a no-alternator set-up is inconsequential. But the weight discussion can affect everyone, not just the alternator experimenters.

[MetroMPG]

It sounds like the best solution is still solar panels on the roof to lighten the alternator load when driving in bright sunlight and then the cost of the solar panels comes into play but at lease they will last the life of the vehicle and not require additional expendature. Plus on a bright day you can crank up the radio and use the excess energy!

It's a good point. 7 or 8 amps worth of solar would cost me roughly $700 though :eek:

[JanGeo]

You are getting the wrong cells - raw cells with 5.5 amp output crate of 50 for $450 last time I checked was over a year ago. 22% efficiency!!! 22 in series and 2 sets in parallel would give you about 14.5 volts at 11 amps and cover the hood in area 125mm square cells jet black no markings on them back side is an aluminum plate and contacts. As far as I know theses are the best cells on the market that anyone can buy.

OOPS!

http://www.sunpowercorp.com/solarcells/

[Brock]

In my case my car already weighs in at 3200 lbs. Throwing an additional 120lbs in the back is nothing to the car itself. It's like another person in the back seat. My typical commute is 11 miles to and from work, 1 stop sign each way so the added weight likely wouldn't affect me the way it would in normal stop and go city driving where weight really kills mileage.

For cost if it were all new
2 golf cart batteries - $150
1 Xantrex 1500w inverter - $100
1 Iota DLS-55 charger - $150
#4 wire from the back to the starter battery - $25
$425 total. I already had the heavy wire run for the inverter in the back, I just run the power back the other way in this case. I had the used batteries so I don't care if I run them in to the ground. The charger is one of two I use to charge my home battery bank in a power outage from a generator. So it was really just my time to set it up. I would not recommend this to “save” money. I highly doubt it would every pay for itself.

With solar I would need at least 2 KC120's to offset my load, at least $1200 and if I spend that much on solar panels I want to get the most out of them, that is to have them have them aimed correctly at the sun and use all the power they make. Oh and the wind drag from the solar panels would likely cause me to use more diesel then I am saving with the alternator disconnected. Maybe if you bought laminar (flexible) solar cells at twice the cost of regular flat panels cells, but that would be at least $2400.

Again my car once warm draws about 100w or 8 amps with nothing on, no radio, no DRL's, no fan or AC. That all just adds to the base 100w load.

And yes the fuel pump is mechanical driven off the engine. I am not sure what the car is doing with the 100w, but it uses it for something.

[MetroMPG]

You are getting the wrong cells - raw cells with 5.5 amp output crate of 50 for $450 last time I checked was over a year ago.

Linky?

[JanGeo]

You know if you tapped into the inverter and the charger you could increase the efficiency a lot - the inverter pumps up the 12 volts to about 120-180 VDC then chops it into a square wave - the charger takes the AC and rectifies it into 180 VDC and chops it back down to 14 volts. You should be able to jumper into the inverter internal high voltage DC and connect it directly to the caps in the charger and eliminate the fet switching and rectifier losses. Actually if you ran more about 18 volts and used a switching regulator power supply to drop it down to 14 for the vehicle it would be most efficient. And that could be done with a single FET or power transistor good for plenty of amps.

[zpiloto]

Metro you have a 10% gain with an unbelted alternator do you had any data if you just removed the load from the alternator and not the belt. Maybe install a kill switch to remove charging when not needed. Any thoughts on if that would give a noticeable increase in FE may 2-3%

[Brock]

JanGeo this is true, but I wasn't as worried about efficiency at first since I was really just seeing if it made a difference and if so how much. Probably the easiest thing to do would be to go with a 24v battery bank and a 12v charge controller and let it do it's thing, the trick is getting up to the 50 amp range, well that is easy, it's just how much it costs. For instance I use an Outback MX-60 charge controller and it will take any voltage up to 140vdc and charge either 12v, 24v or 48v battery banks and you can set bulk, absorb and float voltages and times. Very nice, but they run $550.

The thing I really like about the iota chargers is you can feed them anything from 90 volts to 180 volts, AC or DC and they put out a rock steady 13.4 or 14.4 volts DC. I didn't believe it at first but someone who dug in to the unit tried and now uses it on his electric truck to charge a 12v battery from his traction pack for all the old existing 12v items.

[MetroMPG]

Metro you have a 10% gain with an unbelted alternator do you had any data if you just removed the load from the alternator and not the belt. Maybe install a kill switch to remove charging when not needed. Any thoughts on if that would give a noticeable increase in FE may 2-3%
I'd wager the belt doesn't represent *most* of the gains I measured. Maybe a couple per cent of the 10 total. But I wouldn't know unless I tested it.

I've been waffling between rigging an electric water pump (so I don't have to worry about any belts at all), and putting the full belt back on and rigging a switch.

We'll see what winter brings. I'll probably be a lot less likely to be tinkering (adding/removing the belt for long/short trips), which may encourage me to use the fuse/switch.

[JanGeo]

The thing I really like about the iota chargers is you can feed them anything from 90 volts to 180 volts, AC or DC and they put out a rock steady 13.4 or 14.4 volts DC. I didn't believe it at first but someone who dug in to the unit tried and now uses it on his electric truck to charge a 12v battery from his traction pack for all the old existing 12v items.
I bet a 35 amp switching Vector charger will operate over such a wide range of input voltage as well and they sell for about $65 - I have a bunch of them. My point is that with a $3.00 transistor and a decent core with a bunch of turns of wire and a few bucks of components you could build a switcher to drop any DC battery voltage down to 14 volts at a pretty decent current. That iota charge controller doesn't list any current levels but it looks like it should work pretty well in bulk mode while you are driving.

[JanGeo]

Nice thing about an electric water pump is that you can continue to get heat from the heater with the engine off like when stopped at a light with engine off and regulate the pump speed (wasted energy) increasing it when it is needed like when you are burning a lot of gas and not a function of engine RPM so that lugging it on a hot day you could run the water pump faster for more cooling etc.

[MetroMPG]

You are getting the wrong cells - raw cells with 5.5 amp output crate of 50 for $450 last time I checked was over a year ago. ...

http://www.sunpowercorp.com/solarcells/
Thanks for the link, but that's the manufacturer (no info on the site about purchasing). I'm curious where you can buy the cells retail. Do you still have a link for that?

[JanGeo]

If you contact them directly you can purchase them by the crate of 50 cells - they gave me pricing but didn't get to the final "take my CCard number please".

[onegammyleg]

On saturday I replaced the battery in my Swift.

I had know it was bad since I bought the car a few months ago , and as its getting colder (and batteries dont like cold) the big block 1 litre engine has been getting slower and slower to crank up and fire.
The battery's capacity is suitable for engines over 2 times that size , so for it to be struggling to turn the small engine I knew it was dead.

I have been noticing the car was a little down on power as well compared to when I bought it.

Amazingly when I repalced the battery engine power is back to normal again.

Ime supposing that the dead battery was always under volatage and wanting a full charge and that the power loss was from a full loaded alternator.

Unfortunately it will probably show up in this tank full FE test. :mad: , but interesting anyway the effect of the alternator on power and FE.

[Brock]

Oh, one thing I use a lot is a Deltran water proof battery tender. It charges at a lowly 800 mA up to 14.6v and then drops back to 13.2v float. I would strongly recommend one of these (or a larger version) if your messing with a disconnected alt. The battery will die a quick death cycling it without a good true full charge. I use this charger on our van, I suspect the alternator is a bit off in the van and never full charges the battery.

On the wagon the Deltran will show a full charge in 30 minutes and the van takes 4-6 hours.

Even running the alternator as normal the cars starts much quicker in winter and I figure it doesn't have to run the alternator as hard to get the battery charged back up after sitting a while since it starts “full”.

Even a solar charger would likely work in most cases for this "topping off" of the battery

[JanGeo]

Definately Brock - most electrical systems if not run for hours will not charge the battery as much as it needs. A new battery should be charged at a slow rate for about a week before it really gets the self discharge down to under 0.1 amps. Deltran makes some really great chargers . . . just wished they made a really high output current version.

[MetroMPG]

For those following this thread, I've updated metrompg.com with an article on this topic, summarized and describing my experiment in more detail:

http://www.metrompg.com/posts/photos/chart-alternator-s.gif (http://www.metrompg.com/posts/alternator-optional.htm)

http://www.metrompg.com/posts/alternator-optional.htm

Thanks to Brock for corroborating the results with his Jetta.

[kickflipjr]

You seriously have a bungee cord as your water pump belt!
Arent you worried a bit (I guess it's better then a bike innertube).

Great article metro!

[MetroMPG]

Yep, bungee. Bungee kicks *** compared to bike inner tubes. I'm thinking of making a second one as a backup. There's room on the pulley for 2, side by side.

I'd rather have a smart electric water pump, but I only know how to make a stupid one. And I'm lazy. So bungee it is!

[rh77]

Great Experiment as always!

I wonder if you could hook up a switch that's tied into the alternator's draw to switch the load on and off...

For example, on decel with engine on, you could flip the heavy-duty switch to begin charging (kinda like TangoJetta's fuse, but with a switch). This may extend battery life.

RH77

[JanGeo]

Another thing to consider is the injector response is changed slightly when the battery voltage is reduced - think about it - it gets a pulse of a certain voltage which may be the full battery voltage through the ECU. Lower that voltage and the valve may open a little slower and end up leaning the air/fuel mixture - anyone ever trim the supply voltage to extend the mixture range? If anything it could affect performance at higher RPM.

[onegammyleg]

Great Experiment as always!

I wonder if you could hook up a switch that's tied into the alternator's draw to switch the load on and off...

For example, on decel with engine on, you could flip the heavy-duty switch to begin charging (kinda like TangoJetta's fuse, but with a switch). This may extend battery life.

RH77

Perhaps it wasnt noticed last time I said it , so Ill say it again ,, it wouldnt be hard to make up a switching arrangement so that the alt only charges when neutral is selected and the brake light is on.
This likely would mean you are stopped at the lights idling or rolling down a hill.

Alternatively it could be switched by a vacuum switch.

Of course keeping an eye on an ammeter and voltmeter gauge set would be handy just to make sure your not leaving the battery discharged.

[cfg83]

Brock -

Oh, one thing I use a lot is a Deltran water proof battery tender. It charges at a lowly 800 mA up to 14.6v and then drops back to 13.2v float. I would strongly recommend one of these (or a larger version) if your messing with a disconnected alt. The battery will die a quick death cycling it without a good true full charge. I use this charger on our van, I suspect the alternator is a bit off in the van and never full charges the battery.

On the wagon the Deltran will show a full charge in 30 minutes and the van takes 4-6 hours.

Even running the alternator as normal the cars starts much quicker in winter and I figure it doesn't have to run the alternator as hard to get the battery charged back up after sitting a while since it starts “full”.

Even a solar charger would likely work in most cases for this "topping off" of the battery

I looked up the "Deltran water proof battery tender". Could some circuitry go between that and say a Uni-Solar flexible solar panel (FLX-11) with these specs :

Rated Power (Wp) = 10
Max Power Point VMPP (V) = 16.5
Max Power Point IMPP (A) = 0.6
Short Circuit Current ISC (V) = 0.8
Length/Widht = 21" x 17"

The max Amp of 0.6 may be too wimpy, yes?

If no, then would a smaller Deltran charger be more appropriate?

Or maybe skip the charger alltogether and attach the solar panel directly to the car via some simple cicuitry, yes?

Thanks,

CarloSW2

[onegammyleg]

Quote:
Originally Posted by Brock
The battery will die a quick death cycling it without a good true full charge. I use this charger on our van, I suspect the alternator is a bit off in the van and never full charges the battery.

On the wagon the Deltran will show a full charge in 30 minutes and the van takes 4-6 hours.

Even running the alternator as normal the cars starts much quicker in winter and I figure it doesn't have to run the alternator as hard to get the battery charged back up after sitting a while since it starts “full”.

Even a solar charger would likely work in most cases for this "topping off" of the battery

I dont fully agree with the statement ¨The battery will die a quick death cycling it without a good true full charge.¨
Lead acid batteries die most often from water loss from overcharging , being left disharged or undercharged for long periods of time and to a lesser extent overheating from external sources.

If a switchable ALT was employed and the battery returned to full before switching the engine off (or charging of AC at home up to full) then I really doubt any significant life reduction of a battery.

In fact , it may even extend the life if the car is always overcharging it.

I think it would need some experimentation to bust or umm ,unbust? this one , unfortunately the results would take years to obtain and even then , there are many variables that can affect battery life even in normal service.

[onegammyleg]

,, it wouldnt be hard to make up a switching arrangement so that the alt only charges when neutral is selected and the brake light is on.
This likely would mean you are stopped at the lights idling or rolling down a hill.

Alternatively it could be switched by a vacuum switch.

I have revised my idea , , just have it switched when the brake pedal is pushed.
The now charging ALT will also give a braking effect as well.

This could save on brake pad/disc wear + with the FE savings from effectively no ALT it must come out on top against the possible life reduction of the battery.

i think its worth a try

[onegammyleg]

What poo-poo's that idea is that ime normally coasting in N by the time I touch the brake pedal. :)

[MetroMPG]

What poo-poo's that idea is that ime normally coasting in N by the time I touch the brake pedal. :)

Me too. An alternator that only charges during braking, idling or engine over-run would rarely get used in my car. I hardly do much of those things - the battery would be dead pretty quickly.

Besides, what about those massive losses to belt friction and the pulley fan while the alt isn't being used? So wasteful... :D

[Silveredwings]

Me too. An alternator that only charges during braking, idling or engine over-run would rarely get used in my car. I hardly do much of those things - the battery would be dead pretty quickly.

Besides, what about those massive losses to belt friction and the pulley fan while the alt isn't being used? So wasteful... :D

From the sounds of it, you'd be running a loss just for energizing the alternator field windings. :)

[MetroMPG]

OT - Silveredwings: You sold the BMW too? Did I miss a thread? Are you bicycling everywhere now?

[JanGeo]

Me too. An alternator that only charges during braking, idling or engine over-run would rarely get used in my car. I hardly do much of those things - the battery would be dead pretty quickly.

Add to that my xB adds more fuel if the electrical load increases even at idle.

[Brock]

Jangeo Deltran actually makes a 5.5 and 20 amp version as well but once you get up to about 20 amps I would suggest the Iota line with a smart controller, they are cheaper for charging amp.

Gregg you are correct, maybe I wasn't clear. Overcharging a battery is bad for it. When I say a fully charged battery I am assuming a safe good full regulated charge, definitely not over charging the battery. Also deep discharges in particular a complete discharges will and do damage a lead acid battery. The longest life, or most watts out of a battery will be obtained by cycling the battery to abut 70% charged or sucking about 30% of the power out and then fully correctly charging it again.

And yes most car alternators do a poor job of correctly charging a battery and often over charge the battery thus shortening its life.

[Silveredwings]

OT - Silveredwings: You sold the BMW too? Did I miss a thread? Are you bicycling everywhere now?

Yes I sold both the Passat and the BMW convertible (I'll sure miss that one) and got an '02 BMW 325 wagon. It's really nice. :thumbup: :) Of course 2 days after I got the 'new' one someone ran an '06 Cadillac into it but that's a whole thread wannabe. :(

I'm getting 32 - 37 depending on traffic but I'm still getting used to the clutch and its short gearing.

I need to learn how to fix the entries (http://www.gassavers.org/showthread.php?p=30519#post30519) in my GS garage...

[MetroMPG]

You should definitely start a new thread. Let's hear the whole messy story. (While Matt's updating the garage code - note: looks like he didn't understand part of your post in the link you provided above.)

[Silveredwings]

You should definitely start a new thread. Let's hear the whole messy story. (While Matt's updating the garage code - note: looks like he didn't understand part of your post in the link you provided above.)

OK I will (http://www.gassavers.org/showthread.php?t=2059). Yeah, I saw that. English isn't my first language ... confusion is. :D

[onegammyleg]

And yes most car alternators do a poor job of correctly charging a battery and often over charge the battery thus shortening its life.

I remember seeing in a car magazine once a writeup on a battery out of a very old 6 volt VW beetle.
Aparantly true , this car had the same battery and it lasted 40 or so years before finnaly giving up.

Amazing.

[onegammyleg]

My '94 F150 still has factory battery and alternator. Plus it still has factory coolant, exhaust system, brakes, etc...

Thats prety good :thumbup:

[JanGeo]

Jangeo Deltran actually makes a 5.5 and 20 amp version as well but once you get up to about 20 amps I would suggest the Iota line with a smart controller, they are cheaper for charging amp.

YIKES the price for 20 amps is just CRAZY $315+ as I recall so I went on eBay and picked up a 20 amp variac (not the china version) and added a 35 amp full wave bridge and POOF a variable 20-25amp charger for less than $50 just no regulation. But what happens is I set the voltage with the Variac dial and it automatically tapers off the current as the Hawkers reach their peak charge. But I give it a little extra at the start of the bulk charging for the first half an hour to an hour. My problem is that I want to charge 3 or 4 - 25ah batteries in series at a time so the adjustable Variac was the best solution and the cheepest. A little ripple at the high current is not a problem and towards the end of the charge all the caps in the system filter out the ripple pretty well so no overvoltage. I also got a motor on the Variac that I could use to run some regulation so that as the peak occurs the motor would dial back the voltage - that will come next.

More news from eCycle - they have been testing the next generation of controller with the regen voltage regulation/limiting and have been pushing 400+ amps from 48 volts (4 group 29 batteries) and the results look great. They will probably push the unit to 600 amps peak and 400 continuous (20kw!!) that you can hold in one hand!!!

[Brock]

JanGeo you are the regulator ;) I have a similar setup myself. I just prefer to recommend an automated 3 or 4 stage charger to people who don't understand proper charging or don’t have the time to watch it themselves.

And ya the Deltran chargers are a lot for what they are, but for someone like my brother who wants to connect it and walk away and then forget it for a week, Deltran is the way to go. I really like the Iota chargers in the larger amperages as well and they are more reasonably priced. Again you can build them yourself for a lot less if you know what you’re doing :)

WOW, 20KW that is some serious power. Do you have a link to them?

[JanGeo]

I do have the Deltran 12 volt 5.5amp unit for the Hawkers and it is pretty smart in that it holds 14.9 volts for 6 hours to top off the cells and balance them then drops to 13.5 to float them. Fortunately I have PowerChek modules on the 3 in series so one Deltran does all three at the same time taking a little bit longer to fully charge by like you say - set it and forget it. BUT the variac can put out 1200-1500 watts on 3 or 4 batteries - darn line cord gets hot!

Yeah 20kw is going to be great - just wish it wasn't $995. I think I will setup my scooter and push the motors that I have to 200 amps or more and see how they handle it - from what I have seen they start to moan and really pull when I start pumping in the amps. They are rated at 225 continuous if properly cooled but I only need a lot of amps for a few seconds to get to full speed. The new controllers are not on line yet so don't look for them. They are a join venture with another big company and eCycle has taken the driver section of the controller from Navitas and adapted a newly designed control logic with the proper sensing and limiting to plug into the driver board and made a great new product. More testing is being done with it and maybe a price break will occure later this year. The only thing left is some programming of the limits to make it easier to set - right now it requires resistor changing and some jumpers. I already Told Dan I was interested in one before the end of this year.

[MetroMPG]

Good link, clencher. You're the link man for sure.

[Brock]

The thing I keep coming back to is only the 15% loss on the alternator. I find it really hard to believe that an alternator can turn 85% of the mechanical power in to electrical energy. Maybe they do, but it seems really high to me. Heck a switching inverter is lucky to be 90% efficient with no moving parts. And a DC motor attached to an AC motor is also only about 50% efficient. So how the heck can an alternator be more efficient then a motor inverter? I would think an alternator is about 50% efficient at the top end. Maybe I am all wet, but this just doesn’t sit right with me.

It also wouldn't explain the larger gains we are seeing by disabling them. 100w or less then 1/4 HP should mean a 10% increase in mileage HP wise. Maybe they are 85% efficient at 50% loading and only 25% efficient at 10% or normal loading?

[JanGeo]

Numbers I get from eCycle is that the alternator is about 60% efficient but again at what load. They have a pretty free spinning rotor even when magnitized and slip ring brushes so not much loss there so you get into I2R losses at high currents and the diode drops all the time. It really comes down to how much current the car draws constantly . . . 20 amps at 14 volts is 280 watts doubled for 50% efficiency is still only 560 watts . . . add some belt and fan losses in the alternator and you get less than 1 HP. If you like I can run an alternator on an electric motor and tell you how many watts it takes - all I need is a belt and pulley for the motor.

[Brock]

Sounds like way to much work but I would be curious to know what it really takes to drive the alt.

It's funny you mention that because one of my first thoughts was to drive the alternator in my car off a 1 hp DC motor from the spare battery. Seemed like an evil circle and I thought the losses would be less to go the inverter/charger route. It also allows me to very easily re-connect the alternator for trips or if my wife takes the car.

[MetroMPG]

Posting this message on behalf of John David Shelton, who is the founder/moderator of the MaxMPG Yahoo group: http://autos.groups.yahoo.com/group/maxmpg/

John David is currently serving in Iraq. He has limited bandwidth (thus the request to post this for him).

EDIT: his personal web site: http://maxmpg.org/

Feel free to reply to his thoughts on alternators / charging (prompted by this thread and my write-up at metrompg.com). He periodically reads stuff here at GS.


Do you know of any alternators that are built to be more efficient? Do any of the hybrids have them and if so are they more efficient? What about a DC motor that puts out 14V, would that be a more efficient solution? I read once about a companythat was making a mild hybrid kit with a DC motor in place of the alternator along with a controller and battery or capacitor pack. It would help turn the drive train while also providing DC power.
How about using a clutch sort of like what air conditioner compressors use? That way you could get nearly the same benefits as no alternator connected but the option is there to switch it on. It would probably f reewheel easier than simply turning off the power to the alternator so it doesn't see any load.

I really like the idea of a thermocoupler. You might not get the same amount of power as with an alternator but you could possibly leave the alternator on the vehicle with a kill switch and just use it when the thermocouples can't keep up. Or, install a tiny 35 amp alternator such as was discussed in the thread to be augmented by the thermocouples. When I get back from Iraq, I'm going to look into figuring out how to build something like that. Since I've becom e interested in efficiency I've wanted to try and figure out a way to capture or use the heat energy lost in the exhaust. It's such a waste.

Concerning the turbo alternator, is it possible to put it anywhere on an exhaust? Does a turbo have to be on the manifold? Turbos spin a lot faster than an alternator, how difficult would it be to control the ra te at which a turbo spins an alternator? In a turbo alternator, would an experimentor simply build a fan on the alternator to be spun by the compressed air coming from the turbo or would it need to directly coupled somehow?

The electric water pump is something I'm going to try as soon as I can afford it, along with an electric power steering pump. There are off the shelf systems available for the water pump. The power steering migh t be more difficult. I'd prefer to go with manual steering but it looks as though my truck never had manual steering available as an option and I haven't been able to determine if the Nissan Pathfinder manual steering gear would drop in to my truck.&nbs p;The MR2 has a 12v steering pump and quite a few EVers have used this in their conversions.

And one last thought about batteries. In nearly every make and model of car, no matter what options are installed, the batteries are the same size, usually the same model of battery for every car. My truck, a st ripped down 1998 Nissan Frontier, has the same battery as the truck with all the options. So do I have more battery than I need? If true, make you think how many cars out there have too much battery and are needlessly wasting fuel chargin g batteries that are too big? Is it possible to run a vehicle, especially a small vehicle like a metro, off of a motorcycle sized battery? It would save weight and reduce charging requirements. Also, with a smaller battery it could be more easily r elocated to someplace else on the vehicle to give it a lower center of gravity to help a driver carry more speed through a corner allowing him to brake less. It's a minor amount, but I suppose every bit counts. I'm considering moving my battery to the f rame rails

If anybody has any suggestions for these ideas, please share them with the group.

[MetroMPG]

The thing I keep coming back to is only the 15% loss on the alternator.

I've read figures ranging anywhere from 60% - 90% efficiency. Wikipedia (http://en.wikipedia.org/wiki/Alternator#Battery_charging_system) states 90% efficiency for modern alternators (without any further information).

[MetroMPG]

I'll take a stab at a couple of John David's points...


Do you know of any alternators that are built to be more efficient? Do any of the hybrids have them and if so are they more efficient?

As far as I know, they don't have conventional alternators. The Toyotas and Hondas use DC-DC converters to step down the hybrid pack from high voltage to 13.5 (or whatever). I'm not sure if that's ultimately more efficient than running an alternator, since the gasoline engine ultimately does most of the recharging of the hybrid pack (with regen kicking in some as well).

How about using a clutch sort of like what air conditioner compressors use?

To figure out if that would work, you'd need to know how much power the electromagnetic clutch draws in order to be engaged.

[JanGeo]

You know I was just thinking if we knew the amount of watt hours that we would need to operate for a desired time how about using a higher voltage NiMh or NiCad pack and regulate it to 14 volts out - I have some cheep 20-60 volts input 15 volts out (adjustable) - switching regulator modules 80% efficient and since the NiMh battery can be cycled a lot more than an SLA that could supliment the cars 12 volt battery and you could run a 12 volt to high voltage charger to recharge when going down long hills or slowing down although that recharge time would be minimum - solar or grid recharge would be easy enough at higher voltage.

[DRW]

If true, make you think how many cars out there have too much battery and are needlessly wasting fuel charging batteries that are too big? Is it possible to run a vehicle, especially a small vehicle like a metro, off of a motorcycle sized battery?
I have a downsized battery in my Laser. Originally it called for a 525CCA battery which weighed 35 pounds. I got a smaller 420CCA battery that weighs 28 pounds. Not a huge weight savings, but I needed a battery at the time, so I thought, why not get something lighter? My other car has a 13 pound deep cycle battery rated at 330CCA. Works fine, no problem starting it when cold.

Would a larger battery require more amps to recharge it if the ammount of discharge to start it is the same?

[rh77]

Unfortunately, gassers need ignition/spark to operate, whereas a Diesel doesn't need a battery once running. This and the electrical systems such as power steering on newer cars would require quite the load.

If you know your maximum commuting distance, adjust it for temperature, and perform the calcs, I'm sure a zero-alternator/plug-in system could be implemented. The cost/weight is up to the experts...

RH77

[Brock]

DRW there really isn't much of a penalty for a larger battery beside weight. Well a typical lead acid uses about 1% of its rated power a day to stay topped off. So you could say a typical 440CCA battery, about a 60AH battery uses about .6 amps a day. A battery twice the size would use 1.2 amps a day to stay topped off. Not much in the grand scheme of things, but something.

Rh77, while it’s true that diesels don’t need much power once warmed up they require a LOT to get up to temperature. Even in the middle of summer my car will run its coolant glow plugs (60 amps or about 800watts) until the coolant hits 120F. I believe it does this to warm the engine quicker to help with emissions. In winter the car will run the regular glow plugs (80 amps or just over 1000w) for about 10 seconds before cranking and about 20 seconds after cranking depending on the outside temp. The two sets of plugs never run at the same time though.

[rh77]

Rh77, while it’s true that diesels don’t need much power once warmed up they require a LOT to get up to temperature. Even in the middle of summer my car will run its coolant glow plugs (60 amps or about 800watts) until the coolant hits 120F. I believe it does this to warm the engine quicker to help with emissions. In winter the car will run the regular glow plugs (80 amps or just over 1000w) for about 10 seconds before cranking and about 20 seconds after cranking depending on the outside temp. The two sets of plugs never run at the same time though.

Ahh...didn't know that. From my Diesel ambulance days, (mid-90's Ford E350 Diesels) I don't believe the plugs were warmed at all unless called upon at startup. We ran a unit's batteries down to 0-volts on a long trip back to the station one stormy day when the alternator cable busted loose. It ran fine until we turned it off. Dunno about the emissions...

And yes, I was freezing cold most of the time in the Winter unless we drove a distance and kept it running all day.

RH77

[red91sit]

Another thing to consider is the injector response is changed slightly when the battery voltage is reduced - think about it - it gets a pulse of a certain voltage which may be the full battery voltage through the ECU. Lower that voltage and the valve may open a little slower and end up leaning the air/fuel mixture - anyone ever trim the supply voltage to extend the mixture range? If anything it could affect performance at higher RPM.

I know on Ford ECU's (since 1986) they've had injector pulse -vs- voltage talbes :eek: (in case any one was wondierng)

[MetroMPG]

I wonder how it compensates. I'd guess that probably injector performance gets sluggish as voltage drops, so it lengthens the pulses to ensure enough fuel gets in.

[red91sit]

I wonder how it compensates. I'd guess that probably injector performance gets sluggish as voltage drops, so it lengthens the pulses to ensure enough fuel gets in.

http://www.imagestation.com/picture/sraid218/p5e2e304eb0489df24f1b5e39ed87a8f7/ec388b36.jpg

I'm still tryign to figure out exactly what this does, but it clearly has something to do with voltage and injectors.

[DRW]

On the Mitsu ECU it uses something called 'deadtime' to adjust injector pulsewidth as system volts varies. Deadtime is a set ammount of pulsewidth added to the calculated injector open time. In effect, injectors need a certain ammount of time to open/close, during which they don't flow the full ammount of fuel. If volts are low, the injector opens slower. Once open it doesn't matter what the volts are. The Mitsu ecu has a table of deadtime values that can be changed, and they often need to, since swapping to larger injectors of higher or lesser quality is common in the DSM world. The stock deadtime values follow a similar curve to what red91sit posted.

[DRW]

Oh, one more thing. The Mitsu ECU stops trying to run the car at around 9 volts. There may be a similar cutoff point on other cars. YMMV :)

[JanGeo]

http://www.imagestation.com/picture/sraid218/p5e2e304eb0489df24f1b5e39ed87a8f7/ec388b36.jpg

I'm still tryign to figure out exactly what this does, but it clearly has something to do with voltage and injectors.

As the voltage on the bottom of the graph is lowered (left) the intersection in the curve indicates the amount of added pulse width time - they may stay open a little longer depending upon the magnetic field strength and how quickly it decays which is a function of how hard it was energized.

[BuffaloChips]

Part of the reason for the mileage improvement is, of course, you took away the horsepower drain of the alternator. Sadly, the only thing is, you now are running solely on the battery(ies).

[MetroMPG]

The topic of generating electricity with thermocouples always seems to come up in the alternator-less threads.

[rh77]

BMW's Electronically Controlled Alternator and Regenerative System. (http://www.autobloggreen.com/2007/03/13/video-of-the-bmw-regenerative-braking-system/)

[repete86]

I've thought about removing the alternator and throwing a few deep cycle batteries in the trunk along with adding solar panels to the car once I add a plexiglass shell over the back part of the car. How long do your batteries last at night with your headlights on?

[rh77]

I've thought about removing the alternator and throwing a few deep cycle batteries in the trunk along with adding solar panels to the car once I add a plexiglass shell over the back part of the car. How long do your batteries last at night with your headlights on?

Here's an Electrical Load Test (http://www.gassavers.org/showpost.php?p=15120&postcount=7) Randy performed.

You also have to consider the vehicle's electrical demand from the ignition/spark system. In an additional thread, a calcuation was attempted to see if solar panels could charge batteries, and IIRC, there's just too much amperage required. You could charge them overnight with the grid, but the implication of too much weight is also a factor.

I'd like to find a balance in the equation. As technology progresses, perhaps.

[BeeUU]

Several years ago on a long trip, the alternator quit on my car. A new one was not available at the city I was trapped in....so we drove home on batteries alone. We bought a couple and drove till the car started to run poorly and then dropped in the spare. The fuel mileage was significantly higher and the batteries seemed to last a couple of hundred miles during constant speed freeway driving in the daylight, I used hazards only when it was dusk. I am not sure of the state of charge of the purchased batteries, your mileage may vary.:p

[Maillemann]

Of all the ideas tossed around here, I have to say that the idea of using a thermopile appeals most to me - recovery of waste heat to create energy, no extra batteries, no moving parts. Of course, it'd be expensive. A quick search shows an entry on Halfbakery.com (http://www.halfbakery.com/idea/Thermocouple_20Charger) about it, which includes a link showing a 1kW installation (http://www.hi-z.com/websit07.htm) on a Mack truck. The product brochure page for the HZ-14 (http://www.hi-z.com/websit03.htm) modules they used in that project even states under possible applications: "WASTE HEAT RECOVERY - Engine exhaust powered Alternator Replacement"

Cost? At $124 each, seventy-two of those HZ-14s would run $8,928!

That's a lot of batteries...

[VetteOwner]

hmm i have no idea if its been thrown up at all BUT! what about a electric clutch much like that on an AC compressor to be retrofitted to an alternater shaft? that way you could just "disconnect" the alternator but when you needed a charge you could just flip a switch and re-enguage the alternator. since the AC clutch pulley is relatively frictionless (you give the pulley a spin and it stays spinning for several minutes) i think it would probably work. you would have to change the pullies on your car to compensate for the larger diameter pulley on the alternator(doubt they make a clutch that small)but those you can find all over the place depending on the car.

[MetroMPG]

I wonder what the electric clutch would draw, though. You'd want to determine what's more efficient:

- leaving the alternator spinning while disconnecting it electrically when you want to run altnernator-less, or,

- the additional energy the electric clutch consumes when you want to run with the alternator.

[VetteOwner]

well depends mostly on the car i would assume

[landspeed]

Has anyone tested just disconnecting the alternator electronically rather than mechanically?. If it is as good (or nearly as good), which couldn't you:

(1) Using relays, make a switch that lets you switch between either
a) Using the standard battery and the alternator charging it
b) Using a spare battery pack, with alternator electronically disconnected.

The spare battery pack could be used until it is almost completely discharged, and then removed and charged up at home. You would also try to reduce electrical load as much as possible (mainly by fitting LED lights, HID headlights if legal in your area, and not using the fan / radio etc when using alternator-off mode).

The batteries could be D-Cell Nimh Batteries (11Ah each) - 11 of these would give 13.2V, which is similiar to alternator voltage, and would last for one hour at 145 watts, or 1/2 hour at 290 watts. You could use two sets in parallel to double these times. As most repeated car journeys are short, you would rarely have to use the alternator!. The car would crank from the original battery which would also get charged overnight when the car is parked outside your house (or you can charge with the alternator in emergencies).

Any thoughts on this?

[Bill in Houston]

Has anyone tested just disconnecting the alternator electronically rather than mechanically?<snip> Any thoughts on this?
I like the idea. If you had a switch on the dash to turn it off and on, and a voltmeter reading on the dash, then you could leave the alternator disconnected until you needed to recharge the batteries. And, this would let you drive long trips, after dark, etc w/o worrying about getting too discharged.

Not sure about using D-cells as a second battery pack.

[Silveredwings]

I wonder what the electric clutch would draw, though. You'd want to determine what's more efficient:

- leaving the alternator spinning while disconnecting it electrically when you want to run altnernator-less, or,

- the additional energy the electric clutch consumes when you want to run with the alternator.
Not counting the belt/pulley losses, I think the alternator offers extremely little drag when the field is off. I would think the P/S pump and A/C compressor are much lower hanging fruit.

[Brock]

:) I have a switch that opens or closes an 80 amp contactor between the alt and main battery. I used to manually have to pull the 120 amp fuse, but now I can just flip the switch when my wife takes the car and its back to stock.

I have been using it stock but being in the competition I think I will throw the extra battery/inverter/charger back in there ;) I took it out for winter because the diesel pulls 60 amps (coolant glow plugs) for about 10 minutes after starting, basically until the water temp hits 120F. My second battery would drop below 10.5v with that kind of load for that long. Now I hit 120F in about 3-5 minutes even starting cold.

[rh77]

:) I have a switch that opens or closes an 80 amp contactor between the alt and main battery. I used to manually have to pull the 120 amp fuse, but now I can just flip the switch when my wife takes the car and its back to stock.

I have been using it stock but being in the competition I think I will throw the extra battery/inverter/charger back in there ;) I took it out for winter because the diesel pulls 60 amps (coolant glow plugs) for about 10 minutes after starting, basically until the water temp hits 120F. My second battery would drop below 10.5v with that kind of load for that long. Now I hit 120F in about 3-5 minutes even starting cold.

How hard of a start is it in the summer without the plugs (and maybe an EBH to assist)? I'm thinking back to my Diesel days and how it relied much less on batt. input and how you could take advantage of that. Could you essentially disconnect the cooling fans and hold on to extra heat if you needed to stop while running errands? ...or even an grid-based start to warm up the plugs with a DC transformer.

I just remember being able to drive hours on dead batteries in Diesel - that has to account for some benefit in design...

RH77

[Silveredwings]

:) I have a switch that opens or closes an 80 amp contactor between the alt and main battery. I used to manually have to pull the 120 amp fuse, but now I can just flip the switch when my wife takes the car and its back to stock.
Are you saying your field draws that much? If not, why would you have to kill the connection between your alternator armature and the battery? Are some of your diodes are shorted?

[MetroMPG]

I think it's the rating on the contactor - ie. it's rated to break an 80 amp current. Just a guess.

I like the idea, but my mind keeps coming back to the extra power that has to be spent to energize the coil in the contactor when you're running the alternator!

I learned recently that (a) I have no fuse to disconnect, (b) disconnecting the field sensing/ignition/idiot light wires doesn't disable the field, so I would also need to install a physical disconnect on the main battery wire (as well as the others) if I want to be able to "easily" isolate the alternator while leaving the belt attached.

I think I'd lean towards a simple knife switch.

[Brock]

Are some of your diodes are shorted? Hey that’s the same thing my wife asked me ;)

Metro got it, I just use a big relay to open the connection between the alt and the battery. The relay is just rated to handle 80 amps, basically physically disconnecting the battery from the alt.

I wish I could disconnect the alt all together but when my wife drives to one of her jobs it is usually at night and 40+ miles one way and she doesn't/won't mess with my extra battery setup, and I am not sure it would hold up without a charge for 2 hours in winter. So I have to keep it easily switch able back to stock.

RH77, yes I can start and run at about 20F with no glow plugs or coolant plugs. It is just rough at first and takes forever to warm up and gets bad mileage until it warms up.

Basically the four 20 amp glow plugs only run right on startup for about 10 seconds or so depending on ambient temp. As soon as they switch off the three 20 amp coolant plugs kick on until the coolant is at about 120F. Again I could run without them but would take longer to warm up. I believe they are mainly on there for emission reasons, not really to heat up the car faster, well really both get you to the same point.

But yes I can run it pulling very low power, like 1 amp once all warmed up, just enough for the ECU to think about what it has to do.

[Coyote X]

why not use a latching relay? They only use power to change state and will stay at whatever state they are last set at. So you could switch them on and off all you want without needing a constant drain on the battery.

sample ebay auction here (http://cgi.ebay.com/ebaymotors/Intellitec-100-Amp-12V-DC-BD-Latching-Relay-Solenoid_W0QQcmdZViewItemQQcategoryZ50069QQitemZ30 0094996360QQrdZ1QQsspagenameZWDVW) to see what they look like, but there are many other auctions and stores selling them.

edit- http://cgi.ebay.com/20-pcs-12V-coil-polarized-latching-relays-60A-250V-AC_W0QQitemZ7626681948QQcategoryZ42897QQrdZ1QQssPa geNameZWD1VQQcmdZViewItem is an auction for 20 of them for 50 bucks so if a bunch of us wanted them we could get them pretty cheap.

[MetroMPG]

That's a good idea.

I have seen these mentioned elsewhere and I assumed that's how they worked, but I wasn't completely sure. Thanks for confirming. That counts as one new thing I learned today.

[mrmad]

Generally contactors require little current to hold them closed. For example, my company uses a huge 3 phase 480V, 160A AC contactor on a piece of equipment we manufacture. It is open and closed by 24V DC.

The specs on it are that it takes 540 watts (22.5 amps) to close it, and only 8 watts (0.3 A) to hold it closed. And this is one big contactor, about the size of a small car battery. I would imagine the amount of current to hold an 80A 12V contactor closed would be much lower.

[Silveredwings]

It still seems it would be easier to put a small switch between the regulator and the field. I know...it means opening the alternator and running a couple of new wires in there...

[Brock]

I have some latching relays as well. But the ones I have are not sealed or waterproof so I didn't want to mount them in the engine compartment. I just happened to have the 80 amp sealed relay so I used it. The one I am using pulls maybe 30 mA. I have it set for normally closed in case it fails or opens the alt is back on line and when I do turn it on it is powered from the "extra" battery anyway.

[omgwtfbyobbq]

Anyone try using HT Peltier coolers on their exhaust?

[nathan]

Anyone try using HT Peltier coolers on their exhaust?

not yet, im waiting to win the lottery

[VetteOwner]

what the crap are those?!?!?!

[DracoFelis]

Since the main theme of this thread is pulling electrical use from the alternator (to increase FE), what do people think about this solar array I found listed on Amazon.com?
http://www.amazon.com/Sunforce-50032-Solar-Battery-Charger/dp/B0006JO0X8/ref=pd_bbs_9/103-1931870-3402213?ie=UTF8&s=automotive&qid=1175386897&sr=8-9

I know one amp (and that's probably only in bright sun, less is likely on cloudy days) isn't all the power you will need for running a car (even with the accessories off). However, it should easily be enough to keep a car battery "topped off" while the car isn't running (thereby hopefully lowering the increased alternator load to "charge the battery" when first starting up). And I figure (up to) one amp might also be enough to "help out" while driving the car in the day (possibly raising the gas mileage a small amount when driving during the day).

And the thing I really like about that array (other than the reasonable price, including the "free shipping"), is that it's dimensions almost (but not quite) completely match the top dimensions of my (internal) "trunk cover" on my CRX! This means I should be able to mount that array in the back of the INSIDE of my car, on top of the "trunk cover", but underneath the back hatch glass. So (if I got this array for my CRX), there would be absolutely no loss of aerodynamics by leaving the array always in place (as the array would be in the car all the time). So the only FE loss (from having this array) should be the weight of the array (which is under 15 lbs)!

But my big question is, would the (up to 1 amp of) power from the solar array, actually lower the current generated from the alternator when the car is in use (or would that solar power go "wasted", and the alternator still generate the full current for the car)? I know the array could keep the battery "topped off" when the car is stopped, but what about when running? Is there an easy/cheap way to make sure that the power from the solar array is used BEFORE the power from the alternator (thereby lowering the overall load on the alternator, when driving down the road in the sun)?

I guess I'm kinda looking for some opinions, before I rush out and spend $100 on this solar array. I know $100 isn't a huge amount of money, but it's still a real chunk of change. OTOH if this array really will both keep my car battery "topped off" at all times, and lower the power needs from the alternator while driving during the day, it's likely going to be a "win" (even if not enough power to totally eliminate the alternator, maybe enough to "make a difference).

Comments, anyone?

[VetteOwner]

i highly doubt it...

[landspeed]

What you need to do, is buy two of these:

http://cgi.ebay.co.uk/New-40W-Solar-Panel-10AmpChargeController-is-available_W0QQitemZ190097259494QQcategoryZ41981QQs sPageNameZWDVWQQrdZ1QQcmdZViewItem

And mount them, under your rear window (if you look at my car's shape you can see why I would consider it). They are about 40x40cm.

This would give 80w, which would offset a fair amount of the alternator load,
especially during daytime :)

[mrmad]

Since I don't like the ides of running a total loss electrical system. I see potential for the solar panels shown on Amazon if you combined the charge controllers sold from the same company with a custom relay/contactor to determine when the alternator is used. This way, when the electrical loads are low, the solar panels can help reduce the alternator's use, and at higher loads, no light (at night) the alternator can do its job at keeping the battery charged.

[Brock]

The problem is with solar they are rated at ideal sun angle at solar noon. Once you get that inside the car you will loose 10-30% right off the bat for going through another layer of glass (likely UV coated). Then top that off with being shaded or tilted at the wrong angle and you would be lucky to get 50% of rated power even with full sun not to mention cloudy or shaded conditions.

There is something to "topping" off a battery before driving though. I do this all the time from my home solar array, which I also use to charge my second battery. Basically I use two older marine batteries and swap them out when I get home and put the used one to charge on from the solar array.

In case anyone missed it I use one of the old marine batteries to feed a 1200w Trace inverter, which in turn feeds an Iota DLS 55 amp charger that is connected to the starting battery with the alternator wire disconnected. So my inverter / charger acts as the alternator charging the main battery. Again my problem is I have glow plugs that warm up the coolant pulling 60 amps until I hit about 110-120F on coolant temp. In winter that is 5-6 miles, right now about 3 miles and in the heat of summer that is a mile or so.

[Silveredwings]

Anyone try using HT Peltier coolers on their exhaust?

The problem with these is three: 1) they have limited efficiency, 2) like solar, they get to cost a lot once you have enough of them to be useful, and 3) they don't actually work on heat, they work on heat differential. That means you need to have enough 'hot' surface area to hold the requisite number of the devices and some way to carry that heat away (heatsinks, etc.) to create a temperature gradient on the other side of each device.

I've done the numbers and besides the cost, it's not clear to me that while the exhaust temperatures are high enough, exhaust probably won't give you enough overall heat to make it worthwhile. Engine coolant might have enough heat, but the temps are probably too low. YMMV.

[DracoFelis]

The problem is with solar they are rated at ideal sun angle at solar noon. Once you get that inside the car you will loose 10-30% right off the bat for going through another layer of glass (likely UV coated). Then top that off with being shaded or tilted at the wrong angle and you would be lucky to get 50% of rated power even with full sun not to mention cloudy or shaded conditions.
Good points. Especially since I think my car windows (including the back/hatch window I was thinking of putting solar cells under), are ever so slightly "tinted". Not a lot of tint mind you, but probably enough to make a little bit of difference to a solar cell array. :(

Oh well. I guess I'll just hold off for right now (as those extra power losses you mentioned, are enough to make the 1 amp array I was looking at to be of "questionable value" in my car application), and instead wait for solar arrays to ether come down a little in price or get noticeably more "efficient" (or both).

I do know that there are already solar arrays on the market that peak at around 20% efficient (i.e. in the 3 to 5 amp range, for something that fits in the back of my car, instead of the 1 amp unit I was looking at), although naturally they are the most expensive solar cells (and also the ones hardest to find, as they seem to be in high demand worldwide). And even more efficient (in terms of power produced per surface area used) solar arrays are already in the research stage. Meanwhile solar arrays are also (slowly) getting cheaper to produce over time.

So in the long term, better efficiency (in terms of power for surface area used) and cheaper (to buy) solar arrays will eventually hit the market. It's just a question of "when". For the moment, high demand (worldwide) for solar is keeping prices up (and will likely keep some solar arrays in short supply for much of 2007), but long term the trends are clear (cheaper and more efficient solar cells).

OTOH that high demand isn't all bad, as it's also encouraging solar cell R&D, which should eventually increase efficiency and/or lower prices. And with "already on the market" solar arrays already being "close" for what we need to remove (or at least greatly reduce the use of) alternators in cars, at some point in the future using solar in our cars (if only to make the ICE more FE) will start to make a lot more sense. :D I guess we are just not quite there yet. ;)

[BeeUU]

There is something to "topping" off a battery before driving though. I do this all the time from my home solar array, which I also use to charge my second battery. Basically I use two older marine batteries and swap them out when I get home and put the used one to charge on from the solar array.

In case anyone missed it I use one of the old marine batteries to feed a 1200w Trace inverter, which in turn feeds an Iota DLS 55 amp charger that is connected to the starting battery with the alternator wire disconnected. So my inverter / charger acts as the alternator charging the main battery. Again my problem is I have glow plugs that warm up the coolant pulling 60 amps until I hit about 110-120F on coolant temp. In winter that is 5-6 miles, right now about 3 miles and in the heat of summer that is a mile or so.

Brock-
Is there an advantage to having the inverter/charger between batteries compared to just attaching the marine battery to the electrical system?

I have been using a 5 watt solar panel and solar panel controller to "top-off" my battery while the car sits during the day. Engine off coasting with the headlights on has been hard on my battery. It is a small AGM which I bought for autocrossing because it only weights a few pounds, but it has little reserve capacity.

[MetroMPG]

Bill, I can take a stab at that answer...

If you just attach the batteries in parallel, you increase the capacity, but you still have the same voltage. I think Brock's ECU had a hissy fit when his voltage fell below a certain level. (My car runs OK unless I let the voltage sag very low - like below 11 v - and it doesn't throw a code even when that happens.)

With the DC DC converter, he gets to keep feeding the main battery 13+ volts, keeping that battery, and the computers happy (at the expense of somewhat less total capacity, lost to some inefficiency in the DC converter).

My setup, 2x 6v connected to the 12v starting batt is simpler, but it's also harder on the 12v batt, since I'm discharging it regularly. Brock's will last longer than mine.

It's safe to say to anyone doing lots of engine-off stuff, or running without the alternator: you will cause your battery's premature death, relatively speaking.

Probably more expensive in the end than the fuel you'll save, unless ... a) you have a source of cheap batts, or b) fuel is really expensive, or c) you care more about high FE numbers, and are willing to "pay" in batteries to get the results.

[BeeUU]

Metro:
Thanks for the help, that makes sense.

[Brock]

Yes, just putting extra batteries in parallel in my car the ECU complains and "throws codes" telling me there is an alternator problem. With the way I have mine it keeps the starting battery up at like 13.6v to 14v except right after starting with the coolant plugs running, then I am about 12.4v or so.

And yes the cost savings are really not worth it for the typical driver. In my case I literally had all the parts, extra batteries, big true 55 amp charger and good sized 1200w inverter sitting around. Otherwise the inverter is about $100, charger is about $180 and the batteries new would be about $55. Again this keeps my starting battery healthy compared to just running in parallel with a second battery.

I have found in my case I use about 500w to go to and from work from the second battery bank. Not sure what that turns in to fuel wise. I think a gallon of gas/diesel hold approximately 5kw? So it should be saving me about 1/10 gallon of diesel per trip? I see about a 10% gain on SG running this way.

And 500w should cost me $.05 charging from the grid (usually use solar) and 1/10 gallon of diesel would be $.30. So I save a quarter a trip ;)

[omgwtfbyobbq]

The problem with these is three: 1) they have limited efficiency, 2) like solar, they get to cost a lot once you have enough of them to be useful, and 3) they don't actually work on heat, they work on heat differential. That means you need to have enough 'hot' surface area to hold the requisite number of the devices and some way to carry that heat away (heatsinks, etc.) to create a temperature gradient on the other side of each device.

I've done the numbers and besides the cost, it's not clear to me that while the exhaust temperatures are high enough, exhaust probably won't give you enough overall heat to make it worthwhile. Engine coolant might have enough heat, but the temps are probably too low. YMMV.

I've seen 85W quoted for the max temp diff. (400F peak) of $12 units iirc. The peak temperature is way less than peak EGTs, so they would need to be placed farther down the exhaust and the peak temp there checked, but as long they didn't exceed the max temp, and put out ~5-40W each, I think they could work with aggressive power cuts from led lighting, etc. For someone who does nothing but city, they probably aren't suitable, but for mostly highway, with lots of air flowing over a hot exhaust... :thumbup:

Alright, I did some searching, and there are some that can provide 85W, but they can't go above 400 degrees F, so they might have to go a bit far down on the exhaust. But... they're only ~$12 a piece

The factory battery in my '94 is alive and well. How many batteries would it have gone through by now with alt off operations and at what cost?

A yard I used to live by sold used/tested batteries w/ a month warranty for $15 with a $4 core. Someone should find out!

[usedgeo]

Bill, I can take a stab at that answer...



METRO,
What are you using for a water pump belt this time? I bought some Round urethane belting from McMasterCarr but have not tried it yet. They have quite a few choices. I was going to buy a large urethane O-ring but found this belting.

http://www.mcmaster.com/ You might search for urethane belt if curious.

I am considering alternator less but have not done any experiments yet.

Ernie

[DracoFelis]

I guess that's the reason I pretty much sat this topic out- carrying the extra weight of extra batteries, doing the extra fiddling around, and compromising your battery's life just didn't seem like they'd work out too well in a benefit/cost analysis.
As I see it, the problems we are looking into here, are pretty much the smaller version of the problems (and benefits) a full electric vehicle has. And we do know that an EV can be "cost effective" if engineered correctly. So it all comes down to your source of electricity, and what that power source "costs". Let's look at some of the possibilities:

The alternator being powered by the engine:
This is the "default" situation, that we started with. It's initially pretty cheap to get an alternator, and in fact most cars already have one installed! And in most cases, the alternator can supply all the power you want (subject to having enough gas). The main disadvantages of the alternator are the extra fuel used (due to engine drag), and the extra weight.

Grid charging the starter battery:
This is easy to do, and does save fuel if you disconnect the alternator. But a basic starter battery will die too quickly if you "deep discharge" it like this. So the costs of replacing the battery is high. And you also pay some for the electricity to charge it. Finally, range is limited (however you can use the alternator as a "backup" for when you need longer range). IMHO this is NOT a good choice, if only due to the costs of the battery replacements.

Grid charging better quality batteries:
This is essentially a mini-version of what most full EVs do. Just like a full EV, this MAY BE "cost effective" if the right combo of batteries and charging technology is used. However, the initial costs for higher tech batteries (and charging circuitry) may be pretty high (although much less costly than a full EV, as you are still using gas to move the wheels, just offloading some of the secondary "electrical loads" onto better batteries). And, in addition to the initial costs (and possibly also battery replacement costs if/when they eventually wear out), you still pay something for the grid connected electricity.

Solar power:
This one is interesting. Given current technology (and better solar panels are being developed), you can almost get all the power you need (after doing some "power saving" stunts like LED lights) for a small car's electrical using just good solar panels. They will cost you a bit (probably in the $500-$2000 range) for the higher efficiency panels you would need, and you will have to watch how you mount them (to avoid killing your car's aerodynamics), but you can almost get enough power this way to disconnect the alternator. The "gotcha" (other than the costs, and the hassles of mounting the panels without hurting your car's aerodynamics) is that the sun isn't always out (it's not out at night, for example), and the solar panels also won't generate enough power for those times of heaver than average electrical use. So for both of these reasons you need some other "backup" (batteries that can be charged by the solar panels when the car is stopped, the ability to revert to an alternator when you need extra power, etc).

NOTE:
It seems to me that solar as a "partial answer" might very well be cost effective in the near future (and in some case, already). After all, many solar panels are rated as just over 17V (for charging 12V batteries). This should mean that hooking up a solar panel (with diodes to avoid back drain of the batteries) directly to your car's electrical system (without any fancy "chargers") should still cause the solar power to be used FIRST (as that voltage is even higher than the alternator's voltage), and then the alternator and battery make up the difference. Not only should this lower the load on the alternator (saving fuel), but the "trickle charge" from the solar panel, should help keep the battery "topped off" while the car is sitting (thereby helping to avoid having to use the alternator to charge the battery back up when you first start out).

Waste heat from the ICE:
This has been talked about before. It's costly to do (in terms of initial costs), and may also remove heat you want for other purposes (such as heating the cabin in the winter). But it is one