LED lights

[african_andy189]

Hello everyone i'm new to the forum

I just got a new car - a reanult clio 1.2L 16v( 60mpg rated)swapped for my old toyota corolla diesel estate(55mpg tops!)

Getting my scangauge today - cant wait to see what i can push this beast to do (70mpg?)

I have also just changed most of the bulbs in the car to LED for longevity and i'm hoping less strain on the alternator so less fuel used

I was wondering - LED headlights, if one headlight is typically 55w - 100w, how much fuel could we save if we had all LED bulbs and LED headlights?!

I never realised it before but one headlight is like running a laptop!!

It must be possible to make LED headlights, those cree LED's are available now with 900 lumen - surely this is enough to use legally on the road?That cree LED is 4.2v and 2.8amps!So the problem is cooling!I recon with all LED bulbs and LED headlights you could easily save 150watts - this would surely have an effect on FE?maybe 5-10 percent?

andy

[tstartrekdude]

well i think that you could pull it off, but it would all be hand built, 900 lumens is at the max that that emitter can do, and you are dealing with a lot of heat, if you where to have say 4 in on each side that would be 80 watts at 7200 lumens. that would be a nice bright headlight setup(thats as bright as most HID headlamps and a lot brighter than most incan headlamps out there) if you could focus the beam well, the only problems is that you would have to make a driver setup for the led's and heat...

Lots of heat, the cree's make 8?C/w so that 320?C per light of 608?F...have fun with that, if you had a cooling system you might be able to get away with it, and i would love to see someone try once the mc-e come out(they are a 4 die emitter that african_andy189 was talking about, and are coming out some time this month)

by the way i am a flashlight nerd

[african_andy189]

I am an electronic engineer and have built some pretty ambitious projects, a CNC machine for one, But i just don't think it can easily be done, the cooling is a major problem, the LED's will probably just end up being overdriven and have a shortened life from the heat, part of the reason that even auto manufacturers haven't done it successfully yet.And if they're being worn out all the time it kind of ruins the savings you make in fuel.

I think LED's for all the stop/indicator/fog/reverse/number plate lights and HID is more realistic for the headlights.Has anyone changed to HID's and noticed fuel economy is affected?typical HID's draw about 35 watts compared to about 50 for a normal halogen. So that's 2.5amps less draw off the alternator

[VetteOwner]

true but thats an alternator that makes 120 amps (typical newer car, some older ones made as little as 60) i think the only way it can make a differenc eis if you did all city driving where the car would be idiling quite often (where alternator makes least amps) but highway/ higher rpm situations it makes plenty of reserve power.

but for those of you who want to drop your idle rpm to a minimum it might help it, like my chevette i notice when i have the lights on and press the brake the headlights dim when at idle. but to be fair i knocked the idle down to 300 rpm. (ive had it at 100 rpm before, kinda scary and quiet because it was still smooth as ever)

[theholycow]

Originally Posted by VetteOwner

true but thats an alternator that makes 120 amps (typical newer car, some older ones made as little as 60) i think the only way it can make a differenc eis if you did all city driving where the car would be idiling quite often (where alternator makes least amps) but highway/ higher rpm situations it makes plenty of reserve power.

That statement directly contradicts what many others on this forum say about alternators, that they do not drag the engine and produce unnecessary power - - instead, their field is turned on and off as necessary to keep the battery charged.

[VetteOwner]

what??? ok easy disprove that: disconnect the battery while the engines running, it will stay running and act normal. magic? i think not....alternator is what accually powers your car, battery is there for it to start mostly (also allows you to power stuff when engine is off , etc)

i think i should reword what i said

alternators do drag the engine, BUT at idle where theres minimal engine power (ie engines only turning over 500 rpm) the effects of alt drag are noticeable. but at highway speeds 2K+ the engine is already spinning pretty fast hence spinning the alternator faster thus more easily creating more amps.

(remember back to grade school days moving a magnet slowly in a coil of wire and watching a needle refract a tiny bit? then move it really fast and the needle goes wild? same kind of principle)

some of you in the "older crowd" remember way back when cars had generators? at idle the headlights were dim then you rev them they get brighter? kinda works like that...

[jeep45238]

Some people are forgetting about how an alternator is wired. The positive wire goes to the battery AND the primary fuse block/wiring harness - takin the battery out of the equation doesn't matter (but, if you're fuel injected and you attempt to pop off the positive post, have somebody stop the engine before you hook it back up - the voltage spike from hooking it back up might fry your computer).

If it spins, it's putting drag on the engine. Period. How much varies. Water pumps, alternators, idlers, tensioners, power steering pumps, etc. - they all put a drag on the engine, but how much does vary.

The alt will always do it's best to produce maximum amperage, but the sense wire and voltage regulator are there to keep your electrical system intact and the battery alive.

[Sludgy]

Continuing thoughts from the previous two posts, the voltage regulator is key. A voltage regulator reduces the alternator's field winding current when the voltage get too high. This reduces the alternator output. Without a voltage regulator, an alternator would fry the battery.

Reducing any electrical usage will improve mileage a bit. But, there will always be drag from the belt drive, bearings and cooling fan. I've often thought that an alternator should have a clutch like an A/C compressor to reduce drag. With a clutch, the alternator would charge the battery only when it got low and/or during braking; this would eliminate alternator drag.

[dkjones96]

Originally Posted by jeep45238

(but, if you're fuel injected and you attempt to pop off the positive post, have somebody stop the engine before you hook it back up - the voltage spike from hooking it back up might fry your computer).

Why would you get a voltage spike when reconnecting the battery? The battery is 12v. If anything, you get a spike when you disconnect it from the alternator regulator not responding fast enough to the battery being gone. The battery is more of a regulator / buffer than anything else when the car is finally started unless your alternator is low on output then the battery provides some juice.

[theholycow]

Originally Posted by VetteOwner

what??? ok easy disprove that: disconnect the battery while the engines running, it will stay running and act normal. magic? i think not....alternator is what accually powers your car, battery is there for it to start mostly (also allows you to power stuff when engine is off , etc)

This has been my understanding for a long time. I have heard otherwise but have never actually done the experiment. I think maybe I need to rephrase, or at least emphasize....

Originally Posted by theholycow

That statement directly contradicts what many others on this forum say about alternators, that they do not drag the engine and produce unnecessary power - - instead, their field is turned on and off as necessary to keep the battery charged.

at highway speeds 2K+ the engine is already spinning pretty fast hence spinning the alternator faster thus more easily creating more amps.

But is it actually making those amps, and therefore putting that drag on the engine? Common knowledge on here, which I didn't know until I arrived at this forum, is that it does NOT; instead, as less demand is placed on it, it drags less. This would mean that at higher RPM it would eat less torque, I guess.

[DracoFelis]

Originally Posted by african_andy189

I think LED's for all the stop/indicator/fog/reverse/number plate lights and HID is more realistic

And while retrofitting LED headlights is a real chore (if you can do it at all) retrofitting secondary car lights to LEDs is actually pretty easy to do, if you shop at the right places.

For example, on my CRX, I converted almost all of my non-headlight bulbs (I still have a few small backlight bulbs that are hard to get to inside the car, and while my "fog lights" haven't been converted I'm not currently using them either) to LED modules purchased from http://www.superbrightleds.com . And in most cases the conversion was very simple to do (in most cases I just unplugged the stock bulb, and plugged the LED module in its place), with the obvious exceptions being the small (hard to get to) dash backlight bulbs. A few things to keep in mind:

1) Do NOT buy just on price, look at the specs (light output, color, and beam angle) of the module, and buy on that. If you can't find the specs, odds are good that the module is going to produce sub-par lighting. In my case, I usually bought the brightest modules available in a given shape/size, and as a result many of my lights are brighter than stock. When I tried the cheaper modules I was usually disappointed with the light output.

2) Only buy "white" modules if/when you really need white light. If you need colored (green, amber, or red) light, buy a module that already produces light in the color you need (even if/when your stock bulb was white). By doing this, you will get much brighter/crisper light color, by avoiding the light loss that you always take when converting white light to colored light.

3) Since most LEDs are directional, make sure your beam angle is at least wide enough to fully light the car lens. If you go with a too narrow beam angle you will get a "pin hole" effect from the light. OTOH it's OK to go "too wide", as doing so just uses the natural car reflector to bounce some of the light back out the lens as a normal (incandescent) bulb would also do.

4) Be mindful of what angle the "bulb" will mount in the car assembly. For example, most car mountings expect their light directly in front of them, and most LED modules are built to that assumption. However, if/when you have a "sideways" bulb mounting, be sure to either buy LED modules with a 90 degree bend (to point the light out the side) or extremely wide angle LED modules (that throw light in essentially all directions, including the side). Otherwise, you won't have the light where you need it.

Originally Posted by african_andy189

for the headlights.Has anyone changed to HID's and noticed fuel economy is affected?typical HID's draw about 35 watts compared to about 50 for a normal halogen.

I did some research, and not only are HIDs a bit pricey, but (even more significantly) to be street legal you CAN NOT use stock car optics! Instead, to have legal HIDs, you have to change to new projector type lens optics, and somehow properly mount them to your car! Seemed like much bigger of a project than I was willing to do (or pay for).

However, what I was willing to do, was to replace my CRX's 9005(high)/9006(low) bulbs with Toshiba HIR1(9011)/HIR2(9012) bulbs. I didn't save any power at all doing this (the HIR1 is a stock 9005's 65w and the HIR2 is the stock 9006's 55w), but I did get a lot more light without using any more power. And unlike HID bulbs, HIR bulbs work well with the stock 9005/9006 optics (putting the light in the same places the stock bulbs do), and have a close to normal light color spectrum (i.e almost stock light tint) as well. And HIR bulbs also (unlike HID) come on just as fast as normal halogen bulbs do.

So while I didn't save any power from this conversion, I did get a lot more light for the same power/fuel used. And in a small way I probably do save a little fuel, as my "low beams" are now bright enough that I use my "high beams" even less than I used to use them.

FWIW: Yes, I still consider the low beams (much less the high beams) to be "power hungry" in my car. And even my secondary LED lights make a small difference in FE when they are on (and the headlights a noticeable amount more than that). So my current strategy is to use the lights as follows:

1) High beams are only used for short periods of time, when I need to quickly check something (for example, is that dark patch beside the road a deer that I'll need to watch out for?) on a dark road. i.e. Even on dark roads (at night) I don't run my highs all the time.

2) Low beam headlights are used when I need them to see and/or I'm legally required to have them on at that time.

3) If I simply want to be easier to be seen (overcast skies, heavy traffic, vacationing in Canada, etc) I'll use my secondary (LED powered) lights (i.e. everything except for the headlights themselves, and that includes the front facing white LED modules). By doing this, the car is VERY VISIBLE to other drivers, while still saving the large power usage of the headlights (the LED modules only draw a few watts total, whereas the low beams are 110w just for the 2 bulbs + the power for all the secondary lights).

4) And if it's very bright (and I'm not traveling in an area where lights are required/recommended), I'll just turn off all the lights (counting on a bright red CRX to be visible to other drivers) and save even the minor hit of the power required for the LED modules.

[jeep45238]

Originally Posted by dkjones96

Why would you get a voltage spike when reconnecting the battery? The battery is 12v. If anything, you get a spike when you disconnect it from the alternator regulator not responding fast enough to the battery being gone. The battery is more of a regulator / buffer than anything else when the car is finally started unless your alternator is low on output then the battery provides some juice.

12v + 14v instantaneously for a split second, which is all it takes to fry a computer.

Feel free to try it on your own vehicle with a volt meter on the battery posts - it only takes 2 volts extra. It's not my car.

[AMX]

Originally Posted by jeep45238

12v + 14v instantaneously for a split second, which is all it takes to fry a computer.

Feel free to try it on your own vehicle with a volt meter on the battery posts - it only takes 2 volts extra. It's not my car.

That's not why. Some electrical theory for you: The alternator and battery are in parrallel when hooked up. Therefore, the voltage is only the higher of the two. Say +14V with the alternator running. There is no way you can have 12V + 14V (26V) on that line. The battery and alternator would have to be hooked up in a series circuit to obtain that.

[VetteOwner]

it does screw up the amps for a split second which its all it takes to fry the hairline circuit board paths...

[dkjones96]

Originally Posted by VetteOwner

it does screw up the amps for a split second which its all it takes to fry the hairline circuit board paths...

Can't do that either.

I=Current E=Volts R=Resistance
I=E/R

The resistances through the electrical system will remain constant. Unless voltage goes higher you won't get more current through the circuit and you won't get fried electronics. Think of it this way. The battery in our cars can easily supply 250+ amps but all of that current potential means nothing if the resistance doesn't drop or the voltage doesn't spike like crazy.

Once the car is started it's best to think of the battery as a filter capacitor of sorts. It is really only there to even out small spikes and dips from electronics cycling and a backup if a weak alternator can't keep up. Car will run fine without it but it's better to have it.

[VetteOwner]

Originally Posted by dkjones96

Can't do that either.

I=Current E=Volts R=Resistance
I=E/R

The resistances through the electrical system will remain constant. Unless voltage goes higher you won't get more current through the circuit and you won't get fried electronics. Think of it this way. The battery in our cars can easily supply 250+ amps but all of that current potential means nothing if the resistance doesn't drop or the voltage doesn't spike like crazy.

Once the car is started it's best to think of the battery as a filter capacitor of sorts. It is really only there to even out small spikes and dips from electronics cycling and a backup if a weak alternator can't keep up. Car will run fine without it but it's better to have it.

doh yea i had a brain fart...but yes its true the battery does soften out the spikes from fans kicking on, AC cyciling, etc...

[jeep45238]

I'm a nuts and bolts guy - I'm not a big electronics fella. All I can speak of is from personal experience when some schmoe playing mechanic does the old generator test of popping off the positive lead from the battery, and then puts it back on. They tend to come in needing a new computer if they've got a healthy alternator and battery about 40% of the time. My only advice about this is that theory is just that - it doesn't always work out in real life.

It's very easy to load test an alternator and battery without popping off the positive lead from the battery - you just have to have a multimeter.

[Snax]

Sheesh, not one of you has actually addressed the possible energy savings from switching to LED lighting.

746 watts = 1 horsepower

So even if you could drop 100W of consumption from the electrical system, which really equates to more like 125W worth of draw from the motor when figuring an 80% alternator efficiency, you are still only reducing the load by about 0.17 HP.

That's not much and would probably never payback against the cost of the LEDs, so efficiency is no reason to do it.

[Jay2TheRescue]

Well, LED's are usually brighter, and are long lasting - they'll probably outlast most cars. Great for bulbs that you can't get to easily. For example the front turn signal lamps are a pain to get to on Rusty and I had considered installing LED modules when I put that aluminum grille in it 10 years ago just so I'd never have to take it apart again. Efficiency alone is not a reason to do it, but could be a contributing factor for replacement.

-Jay

[VetteOwner]

theres a flaw to saying LED being brighter, remember LED's are very directional on thier light output, standard bulbs throw equal light in nearly all directions, auto manufacturers design the taillamp housing so it reflects the light that goes backwards out towards the rear and everywhere inside the housing. thus lighting all of it up and easily see even in bright sunlight. those LED bulbs you just plug into the socket typically shine mostly backwards(some have a few LED's radially mounted) so really your getting a brighter light but only in a concentrated spot, the light doesnt really bounce off the reflector to fill the entire lamp housing.

now if you make your own boards that do fill the entire housing then yes they would be brighter. or the cars that come standard with LED tailights, those are also designed to be seen from the side, corner, and straight back.

i dunno even about hard to get to lights being a reason to buy them, really how often does a bulb burn out? i think ive blown a brake light and a turn signal bulb but its taken a very long time to do so.

[Jay2TheRescue]

I know instrument panel lights are the worst. In the past I would buy about 2 dozen bulbs if I had one burned out and just replace all of them while I had it apart. The first time I tried to replace a bulb on the panel I just replaced the burnt out bulb. A month later 3 more bulbs were dead and I had to take it apart again. I have 2 or 3 burned out on The Beast, but I haven't been bothered too much - the DRL indicator is burned out and a couple of bulbs in the radio are gone. My preset buttons don't light anymore. I'll wait till one or 2 more go then take the whole thing apart.

-Jay

[theholycow]

Most of the lights in my GMC's stereo are out. In the time it took them to burn out, I got so used to operating it that I don't need the buttons lit or even labeled anymore.

[Jay2TheRescue]

yes, I can operate my stereo without the lighted buttons, I'm just being anal-retentive about it. There's something that doesn't work exactly right. I honestly think I suffer from some kind of OCD.

-Jay

[itjstagame]

Remove all the lights, much savings compared to changing to LEDs :-).

Anyway, for you electronics and LED wizards, I want to take the LED plunge. I'm starting with dash lights and radio lights because I don't want to trace out the brake and blinker wires and construct bulbs yet.

I found out that one superbright white LED is plenty compared to an old dash indicator light and they're very directional indicators (the idiot lights that is), so I really only want one/light. So I tested and found out all my idiot lights are ground switched from the ECU with a common positive. So it'd be really nice to just change this positive rail to the 3.5V required for the LEDs and be done with it.

What's the best way though? If I'm using 4 LEDs in series I don't mind putting the resistor in for added protection because it's such a small amount of power loss for 4 LEDs, but I would think that the power loss from big enough resistors to create a voltage divider down to 3.5V to drive multiple LEDs would be more substantial. I don't want to change these for fun or for looks, I want less energy draw.

So I was thinking about maybe a small transformer, 1/4 step down would turn my 14.4V to 3.6V and the 'off' ~12V to ~3V (the leds are rated 3.1-3.6V). The question is, what number winds/size would I need and can I ground it to the 12V source? That is have the transformer and battery have a common ground so I don't have to change over the ECU ground for the switching?

Now that I think about it though, I was only planning on 4 LEDs for lighting the dash itself and 4 for the HVAC controls, plus 8 idiot lights, so that's 16 LEDs max in use at once at 20ma each, so we're only talking .32A total, which I guess won't draw too much across a voltage divider and waste too much heat at the resistors. What wattage do you think the little bulbs are? 3-5W ? At 3W that'd be 3.3A, so I'm saving 3A already, woo!

All I know is right now when I turn the parking lights on I can definately hear the engine idle down under load and that's just parking lights. I want to reach the point where this doesn't occur anymore.

[Jay2TheRescue]

I don't know about a transformer. This is what I would use:

http://www.radioshack.com/product/in...entPage=search

Its a solid state adjustable voltage regulator. Its cheap, compact, reliable, and easy to wire up.

-Jay

[theholycow]

Why reinvent the wheel, engineering your own ways to make invidual LEDs replace automotive bulbs using transformers and such, when there's already inexpensive plug-in direct replacements?

[itjstagame]

Because they're prohibitively expensive and not as energy efficient as they could be. Enough LEDs to do what I want is <$10 shipped on ebay as are transformers, resistors, etc. When I looked at superbrightLEDs, $10 wouldn't even get me two bulbs.

Jay, as for the voltage regulator, it looks like the same problem. The output voltage is based on the resitor you chose which is directly based on how much current you're going to flow through it. So if one idiot light is on and I tuned for 20ma then it's ok, but if two come on then my calculations will be off. I basically just want a 3.5V source with 0-1A available.

[theholycow]

Originally Posted by itjstagame

Because they're prohibitively expensive and not as energy efficient as they could be. Enough LEDs to do what I want is <$10 shipped on ebay as are transformers, resistors, etc. When I looked at superbrightLEDs, $10 wouldn't even get me two bulbs.

Good point. We're here to save money and figure out new, better ways to do the same old stuff...so how would LEDs be an exception to that? They wouldn't!

[itjstagame]

Ok, I just looked and maybe that would have been easier for the dash lights. They have #74 bulbs for $1.79 for a single superbright (amber though) (which is what I'm doing) and $2.79 for a more multi directional one. Realistically I probably have 8 idiot lights or so, so that'd be $14.32. Instead I've got an LM317T, some resistors and 8 LEDs, so probably $5 if I try hard. But I've put much more time into this, probably over 3 hours already, maybe heading toward 5, plus I still need to figure out how to 'wedge' them into the bases and I have to keep track of + to - direction (not sure if the superbrightleds.com place has to do that still do or has some special circuit).

I would think if they've got a single LED they must have a voltage divider inside each one. I'm not good at calculating how much energy would be lost through such a thing, at the 20ma a single LED draws I'm sure it's not much. I kind of feel like my way is 'cleaner' as far as number of components and layout, but certainly not in the easiness or looks department.

Anyway though, as you said, I actually only have $6 in my pocket now until next pay day and $14 (though not expensive at all) would have been more than I could handle just for some idiot lights. Besides I doubt the wattage savings will ever break even, even at $5 :-). Of course I don't have any free time and am getting a lot of flak for always working o nthe 'broken' car. I don't have the balls to try to explain I'm really just hacking apart a perfectly good car :-).

EDIT: Meant to say also, the $6+/bulb is for the standard 1137 parking/brake lights, etc. Since I'll be using 20 or so LEDs on these I can just use standard 4 leds + resistor circuits in parallel, so all I need to so is lay them out on a protoboard and shove them into a standard bulb socket and solder like crazy. 100 superbright red LEDs (for tail lights) were like $7-8 shipped and came with the resistors. So I'll easily be saving $30 across the 6 bulbs and shouldn't take much work. The dash is the bigger headache. Although I am planning on a new electronic flasher and probably a dimmer circuit and need to trace and figure out where to wire in.

Jay, btw, LM317T was an awesome suggestion, it's putting out 3.47V whether car is on or off and will handle up to 1A (50 LEDs). The only thing that sort of stinks is I will probably have to make another one for the dash/parking lights because they're on a seperate circuit through the parking light switch and dimmer control. That is unless I really want to trace wires like crazy and hack new circuits to save on a few components....
http://ourworld.compuserve.com/homep...den/page12.htm
Any idea why they'd want a 22k uf cap there? I left that off because I could FIND one, the 2,200 uf caps are D cell size and expensive as hell. Works fine as is.

[itjstagame]

One last thing. Cow's comment about learning a newer/cheaper way to do stuff made me realize I should really document this stuff. For fun and to maybe help someone else. Here's a demo of what I've typed up so far. It'll look much nicer with pictures and moved to a proper .com, but please let me know if you think I've left anything out or see any typos: http://dax.prolixium.com/~itjstagame...s/dashled.html