Why no liquid fuel capacity for EVs?

[omgwtfbyobbq]

It seems that most, if not all electric car builders/manufacturers shun the notion of the ICE, even though an electric vehicle with a large enough pack for most daily use, and a small, appropriately sized gasoline generator for long trips, would exhibit all the efficiency, reliability, and instantaneous power of an EV, with all the range that liquid fuels provide. All while minimizing what seems to be the most costly component, batteries.

The electricity bill to run a vehicle exactly the same size as whatever we drive now would be ~a third of what our current gasoline bills is, and the gasoline cost would drop by ~40% because we would be eliminating the majority of inefficient gasoline engine operation... Unless of course we pulse and glide. But the whole point is that it would open up ~P&G mpg for everyone w/o all the hassle.

Even at homebuilt prices, I bet these would be competative with pure EVs and ICE powered vehicles... They would initially cost a little bit more than ICE vehicles due to lack of volume and battery cost, but as production ramped up, they eventually end up being cheaper than most ICE versions due to the high cost of the modern drivetrain/emissions system, while offering a ~40-75% reduction in fuel costs, better acceleration, fewer repair costs, and longer vehicle life.

While I can understand that most manufacturers can't instantaneously alter their production, they have contracts with suppliers and whatnot, if we don't start seeing 100mpg vettes and 200mpg corollas in the next few years, I'm gonna be mad. And write an email to someone. maybe not... :rolleyes:
But anyway, with gas at $1 a gallon, the electrified drivetrain is more or less equivalent in cost, but now that we've been holding steady at $2-3 for the last few years, there's no reason for manufacturers not to start rolling out fuel efficient, high performance, long range, economic vehicles.

[JanGeo]

Build it and they will sell. A small high quality honda motor of a few HP on a generator still only burns gas at 25% efficiency then add the losses in generating and charging then battery losses and it become a pretty lossy system plus it adds weight to the vehicle - so it becomes something to avoid.
Now a parallel hybrid is something else and is what eCycle is working on so that any combination of ice and electric can be used.

[omgwtfbyobbq]

Can you lend me a few million dollars? ;)
Most small Honda engines seem to be in the ~310g/kwh, and supposedly the average minimum BSFC for a car is ~250-300g/kwh (Prius at 225g/kwh), with the average being somewhere around 500-600+g/kwh, even with the Prius. A small diesel engine has even better consumption numbers with ~260g/kwh. So right now we're at ~60-100% better mpg depending on ICE engine type. Of course, we need to convert that mechanical power to electricity, but there's no reason to charge the batteries in order to power the electric motor when we can just go straight to the electric motor, with the battery pack acting as a buffer, and any extra electricity that's generated charging the battery pack to a certain point if it's discharged.

Like you stated, with a small high quality Honda genset, like the EU2000i which costs ~$500/kwh and weighs ~30lbs/kwh, the efficiency is still roughly ~400-450g/kwh, and even if it goes directly to the electric motor at 80% efficiency, we might as well have a normal gasoline engine. But, even though the engine is pretty fuel efficient as small gasoline engines go, the conversion is only ~60% efficient, so it's very inefficient at turning gas into electricity.

Otoh, there are some very efficient, but pricier, diesel (and I'm guessing gasoline) gensets that run ~$800/kwh, weigh ~60lbs/kwh, and use ~300g/kwh. The motor efficiency is ~80-90%, so we're at a bit under 335-370g/kwh, or ~35-40% better efficiency than the average gasoline car gets. Of course, these are off the shelf items that aren't designed for automotive use and don't have the advantage of mass production that parts used in autos do.

For example, lets say the average small car needs ~8kwh to go an hour through the EPA highway cycle, so we'd need a ~$6k genset. But GM makes small cars that sell for $9k. Is the genset really that much more expensive? I doubt it. Mass production brings the price of stuff way, way down, and since these generators aren't mass produced like an auto manufacturer's parts supplier can, they're expensive so the company can sell very few and still make a profit.

Anyway, there's also the electric motor/controller, and there's plenty of info about these. They seem to run in the $3-5k range with low volume sales depending on size, and the batteries, which are where most of the cost comes from, are ~$500/kwh for NiMH and $800/kwh for li-ions. A 50kwh pack of li-ions, enough to take the Tesla Roadster roughly 250 miles runs $40k. Otoh, an 80 mile range only needs ~$13k worth of li-ions, or $8k worth of NiMH or NiCD batts. So there is a lot of money that can be saved by using a small efficient $6k genset instead of $27k worth of batteries. The majority of day to day driving would be using only electricity, and long highway trips could use the genset at some fixed speed, with ~35-40% better mpg. Even more if the size is smaller so that people have to drive 55mph.

At most, an aerodynamic Aveo with LRR tires built along these lines would be ~$25k using current prices, probably ~$15-20k with mass production. The diesel genset would last an extremely long time due to minimal/extended use, the electric motor is practically bulletproof, and the batteries should last ~50-100k miles depending on type. When the batteries need to be replaced a five to ten years down the road, the price will probably be substantially less, and considering that the cost of oil probably won't go down anytime soon, I think they'd be great for the consumer. :thumbup:

[JanGeo]

Put a ICE in a car and you have to pass emmissions testing and crash testing unless you are converting an existing car. The Li-Ion battery made from laptop cells have other design considerations namely that you have to have enough to provide the watts so that you really can't use too many less or else you will not have the voltage and current that is required. The cells only put out about 3.8 volts at 2-3 amps each under load with a good charge in them. If you do the math on the power requirements you find that the more cells you have the more power you can generate and the longer they will last. When all is said and done it ends up costing a lot more than you think. Now $3k on a small battery pack of Li-Ion cells for a motorcycle size electric conversion makes a lot more sense.

[omgwtfbyobbq]

I don't buy the cells argument you make. We're talking something that pulls down ~250hp and only needs a 50kwh pack, 50electric hp would be equivalent to what an Aveo currently uses, and probably only need the same proportion of instantaneous power, I'm guessing 8kwh (o.k. maybe 10kwh) would be acceptable considering how the aveo accelerates currently. I was assuming we went with NiMH or NiCD and sacrificed some weight for the $4k price tag, or we could go with something like $7k with li-ion.

We could add additional batteries for more range/instantaneous power, and by the time we've hit $40k we'll probably have corvette performance with much more electric range. But then we wouldn't be at the same price point. ;)

As for the comment about requiring crash testing with a small ICE. I'd love to see some info as I'm not picking up anything off of google. I've seen something about how the EPA calculates equivalent fuel economy for an electric vehicle, and they mention if there is any power coming from an ICE then the conversion factor is different, but they still classify it as an electric. I'm thinking that maybe there's some power or displacement limitations. Alternatively, this could be built smaller/light/with three wheels in order to bypass emissions/crash testing as a motorcycle in some states, with better fuel economy and quicker acceleration as a byproduct. The Aveo shell was just to compare the price of something that's currently used.

[JanGeo]

A typical 18650 Li-Ion cell max is 5 amps at 2ah is 6wh of energy so if you need 50hp = 38kw of power = at 10 watts per cell 3a x 3.6v ... 3800 cells * $3.70 = $14,060 = 22.8kwh battery = 159.6 volts at 200ah (Peak charge voltage in 38s x 100p configuration). These are real number from measurements and purchases I have made of some good cost effective cells. Higher output cells are available but would have simular ah ratings and cost several times more per cell. At a typical car energy use of 5 miles per KWH you would have 114 mile range. At 500 cycles you would have a life of 57,000 miles.

[omgwtfbyobbq]

Huh, I never knew 18650s couldn't provide that much power... I was thinking of 1.2V 10ah NiMHs, which according to the manufacturer, can be pushed to 30ah continuously, and 50ah for short periods of time. At 1.2v(50ah)=60w, for 38kw of power I'd need ~650 cells, which would be ~$3,500. At the 30ah rate the pack would be ~$6k. At 5mile/kwh the pack would take me ~40 miles assuming 10ah, however, an Insight is roughly 10mile/kwh, and I figure an Aveo with similar CdA/Crr could be done, so ~80 miles in that case. The 100k mile was for ovonics NiCDs, which supposedly can clock 1000+ cycles at 80% DoD.

According to your calcs the Tesla Roadster must be pulling ~12amps to generate 250hp=185kw peak power from a ~55kwh pack. How are they able to pull so much more max current? Assuming I didn't bork the calcs someplace. ;)

[JanGeo]

First a 1.2volt NiMh will drop to about 1.0 volts at 50 amps (don't mix ah - Amp Hours with A - Amps). I have some 12ah "F" cells that are good for 50 amps continous and I have run them at that power level so you get 50 watts. Now you want 250hp = 190,000 watts = 3800 cells but you end up with maybe 10ah or about 10-12wh per cell at a cost of about $8 per cell = $34,000 plus you have to balance them like crazy because they self discharge so much and you also have to put 20-50% more kwh into them to fully charge them and they will get hot if you fully charge them. You really shouldn't put them in parallel when charging and they only produce about 1 volt out at full load, this requires more in series and more balancing circuitry and then the weight is higher also.

[omgwtfbyobbq]

Oh no, I'm still shooting for the 50hp figure, which should only require ~$7k worth of cells by your estimate. Of course load balancing stuff would be required, but I'm figuring they would only be fully charged overnight, with each series string being charging individually. The "extra" current from the genset, when it's on, would push them to ~80%, or whatever they can be quick charged to. The cells I was looking at were ~$5.50 a cell, and supposedly would run 30a continuous (just replace where I stated ah with a, except for the actual 10ah rating of the battery ;)) and 50a for short periods of time. So we're talking 50a per cell, or ~700+ cells to make 35kw, which should also provide ~80 miles assuming a insight'ish glider, and cost $4,400 (800 cells at $5.50 per cell) plus tax and S&H.

Personally, I'm probably going to with half that in a small faired trike, but that's a potential pet project, among many. Hopefully I can run ~30hp in a 400lb vehicle, or the equivalent of 150hp electric motor per ton.

[JanGeo]

Yup a trike would be the way to go and hide the motor and batteries and keep the pedals functional. You will not need 30hp unless you want to go really really fast. I still don't like using NiMh cells that much - have a bunch of them and they are a pain to keep charged properly - they can go dead in a week just sitting with nothing connected to them where as Lithium will stay charged for months.

[Silveredwings]

Here is an interesting read (http://www.evconvert.com/eve/the-battery-dilemma) about traction batteries for an EV.

You may be over-engineering the motor / battery specs (a 50 hp motor may be more than needed in a car, muchless a trike). Usually the limiting factor is the current capacity of the controller itself.

[omgwtfbyobbq]

Yup, if the car were using an AC motor, 50hp may be the equivalent to a 150hp gasser because they rev to 10K+ rpm, but DC's only be able to equate to a gasser of roughly twice as much power because they don't rev as much as ACs. In any event, the torque would probably surprise most.

For the trike, I'd like to build something that's obscenely fast, but still is obscenely economical as well as affordable. The Tesla Roadster, just in stripped down microcar form. I doubt there would be much interest because it would be fairly spartan, but an ideal 12s quarter mile, ~1000mpg EPA combined energy equivalent, the ability to be powered by a single 100-200W solar panel, along with a sub $5k price tag for the DIY'er would be too cool. :D

[JanGeo]

Something I found this morning . . .

http://www.evconvert.com/eve/the-battery-dilemma

— John Westlund May 10, 10:30 PM #

We had the better batteries 10 years ago. The Ovonic NiMH. 70 wh/kg specific capacity, 1,750 cycles to 100% depth of discharge. Robert Stemple, chairman of Energy Conversion Devices, quoted them at $150/kWh for a production run of 20,000 cars.

General Motors, not wishing to see the electric car go mainstream, sold the patent to Chevron Texaco. Chevron Texaco vigourously protects this battery and has sued Toyota for making a similar design. Further, with the oil company winning that case, it can now restrict the maximum AH size of the batteries to 10 AH. This prevents them from ever being used in a road EV, as it is not practical to go above 400V or so and NiMH cannot be charged in parallel with ease. Further, this oil company is responsible for about half of the price premiums on Today’s hybrids; they charge $1,200/kWh for the battery when it could be much cheaper!

At 70 wh/kg, a midsize car with attention to aerodynamics could have 200+ miles highway range with a 500 kg, 36 kWh pack costing $5,600 and lasting well in excess of 300,000 miles in theory. This battery has been denied to us. This battery would allow hobbyists to make 120-150 mile range conversions a norm, and 200-300 mile range conversions a possibility.

[omgwtfbyobbq]

To bypass getting the crap sued out of them, iirc electro energy is selling their NiMH design, which supposedly is similar but better than the ovonics design, to the US military/government at something like $500/kwh. Here it is. (http://ir.electroenergyinc.com/releasedetail.cfm?ReleaseID=195725) Some more (http://www.greencarcongress.com/2006/05/electro_energys.html).

[omgwtfbyobbq]

I was searching for something relatively unrelated and was pointed towards this article. (http://www.motherearthnews.com/Alternative_Energy/1993_June_July/1993_Update__Dave_Arthur_s_Amazing_Hybrid_Electric _Car)

Using parts that he had purchased for under $1,500, Dave designed and built an engine system for his Opel GT that could propel the car 75 miles or more on a single gallon of gas! Dave's Opel was a hybrid electric vehicle. That is, the car was driven by both an electric motor and a conventional internal combustion engine. An array of six-volt batteries provided the direct power for the electric drive, while an efficient six-horsepower (hp) lawnmower engine ran continuously to generate power for and recharge the batteries. The combination of power plants made the car amazingly versatile. The batteries alone could be used for trips of under 25 miles, but the car had an unlimited range as long as the generator engine was running and the driver didn't have a penchant for drag racing

A 25-mile test run using the nine-hp diesel engine showed that a gallon of fuel could produce sufficient amperage at 36 volts to drive the car two hours at 45 mph. That's 90 miles to the gallon. If the terrain had been a bit less hilly, the average speed would have been closer to 55 mph. It's important to realize, however that stop-and-go traffic shortens the range and reduces efficiency because of the heavy current draws (600 amps) in taking off. That's where the surge current (cranking power) of the battery comes in. A great deal of city driving will certainly affect overall fuel economy.

Short trips can be made all electric, and with gasoline/electric prices about the same per kwh, an electric motor that's ~three times more efficient equates to 1/3rd of the fuel costs. And ~90mpg with a diesel "generator" at 45-55mph in a pickup sure sounds nice to me. I bet there are plenty of classic car shells that we could appropriate for this kind of system, and see great mpg numbers without having to shut the engine off, or worry about traffic, etc... Just hit the cruise control and watch 100mpg roll by. :cool:

[omgwtfbyobbq]

I don't think they're that bad, especially when comparing low load/high displacement to high load/low displacement gasoline engine operation. For instance Honda's small (~15hp?) GX series seems to have a minimum BSFC of 313g/kwh, and at minimal efficiency, the Prius' engine is operating at ~672g/kwh (assuming 224g/kwh is 36% eff (http://www-personal.engin.umd.umich.edu/~chrismi/downloads/HEVModel/FC_PRIUS_JPN.m), and 12% is triple this), so pumping losses are pretty big even in today's advanced variable valve atkinson cycle engines. Iirc a member posted that they used as much fuel at idle as they did cruising at ~35mph(?) or something. Putting a small disp engine in a gasser would work as well, but image how slow a 20-30hp 3000lb car would be...

edit- playing around with metrompg's resistance calculator and the Prius' supposed stats (Crr=.01, Cd=.26, A=2.16m^2) seems to indicate that at 50mph, the Prius' engine is only operating at ~21% efficiency, and BSFC is ~384g/kwh. I'd bet small gasoline generators designed to run at one speed could easily return ~250g/kwh.