jmead

Optimas were my choice originally, but after doing some research I found they have been having quality control issues and were not performing as well as they did originally. The Odyssey batteries I settled on are very similar, except they use a flat plate configuration instead of spiral which allows a greater capacity in the same physical size. My batteries are only slightly larger, but have 73AH compared to the 55AH of an optima. Very similar discharge/charge characteristics though, with greater expected life cycles and a superior warranty too, all for about the same price. I am very happy with my purchase. They do look like normal batteries though, not nearly as futuristic in appearance as the "6-pack" design in my mind. I'd like to experiment with orbitals but I couldn't find anyone to sell me any? My next project will be higher voltage, something like 240v of orbitals would be perfect.

From the power per unit of weight perspective an engine can't be beat. One pound of gas contains 17500 BTU of energy, which is about 308,000 watt/minutes, or 5,133 watt/hours. My whole 720 lbs pack of batteries holds 10,500 watt/hours, or about the same as 2 lbs of gas. 1 Gallon weighs 6 lbs, so my batteries hold the equivalent energy of 1/3 a gallon of gasoline. But I can travel 50 miles on that amount of energy, where a gas car that gets 30mpg can only travel 10 miles.

This is the basis for much of the efficiency increase over a typical car engine running at a fraction of its peak output most of the time. A small engine can run at peak constantly, can be smaller, weigh less, can be tuned for use at that particular speed increasing effeciency even more. But if you look at total fuel burned vs total distance traveled the batteries are going to win every time (including fuel used to generate your electricity) The electric motor/batteries are over 80% efficient, all the time An engine is at most 30% efficient, peak. The goal is not to eliminate the need for batteries. It is to eliminate the need for an engine. Once I can afford a 30kwh pack of LiFePO4 that generator is toast, and I'll never look back. If I didn't commute over 50 miles every day, and have a girlfriend that lives 90 miles round trip away during the year, 300 miles during the summer I wouldn't even consider it.

Why would you want to? If you can drive 50 miles for $1 in electricity, or $2.50 in diesel fuel, why would you ever want to use the fuel? Unless you were traveling long distance and carrying enough electricity isn't feasible. Is plugging in that big of a problem? Why is plugging in a huge hassle, but driving to a gas station, waiting in line, pumping this smelly fluid whose fumes cause cancer and are extremely flammable is the better of the two choices? I don't get it, I wont miss filling up every few days at all. This efficiency isn't anything special, it only seem like it compared to the horrendously inefficient vehicles we are used to. Its important to note this figure it based on 50mph, at 70 its probably half that. Air resistance goes up as the square of your speed, so there is a gigantic difference in the power required to drive 60 vs 80. That isn't much better than what a geo metro can get driven at the same speed, without any electric assist at all. Even in my car rated 32mpg highway if I slow down to 50mph I can get in excess of 45mpg, and its a 3000 lbs non-aerodynamic box, with an engine 20x bigger than necessary to maintain this speed. A prius driven by a energy conscious individual can get over 100mpg without ever being plugged in. The generator is really an afterthought for that 2% of the time when the batteries aren't enough to get where I'm going, I see no reason to use it more than is needed.

no need to charge the batteries with the generator, you could simply drive the car using the electricity being produced by the generator. At 10kw it'd only be enough to travel maybe 50mph or so on level ground. If you were traveling faster than this, say you were going 70 and consuming 17kw of electricity, the first 10 would be provided by the gen and extra 7kw would be coming from the batteries.

Plugging some quick numbers into the incredibly handy EV Calculator I see that the a 10kw output should be capable of sustaining a cruising speed of 65mph on perfectly level ground. In this scenario the batteries will be used only for additional load (incline, headwind, increased speed), and they will receive the surplus output when load decreases (downhill slopes, tailwind, decreased speed). If I then extrapolate this with data available on diesel generator fuel consumption, which appears to be 210-240 grams fuel per kWh. Therefore 1 hour at 10kw will consume 2400 grams = 5.3lbs of diesel fuel. Diesel weighs about 7.2lbs per gallon, so this equates to .75 gallons of fuel to achieve 65 miles. Good enough for me...

Each is capable of 600 ft lbs! Combined with a 2000 Amp zilla EHV (extra high voltage - 348v) you'd have 1200 ft lbs of go. Thats alotta go

I may need to go to 3rd for highway use, I haven't taken it up that far yet (not registered, working on it), so I don't really know. Ideally your rpms are around 3-4k at cruise, this is where the motor is most efficient. Direct drive is more stress, but it depends on the setup. If you've already got way more motor than you need, something like twin motors or an 11", that extra few hundred amps starting out in 3rd (close to what a direct drive would be) doesn't make a big difference. But with the 9" I've got it would be pushing things. Maybe because it is such a light car I'd be OK, but since I live in a very hilly area I'd be afraid of frying my motor up a long hill. Now I can just watch my amps and drop it down a gear (higher revs for same total power = less amps) if they are too high for too long. The transmission tunnel is the perfect location. Twin motors direct drive to the diff and located right between the seats would be the perfect setup in my mind. You could then just place batteries wherever you wanted to get the weight balance perfect and the center of gravity as low as possible. It'd annihilate anything on the road.

That would be ideal. I really contemplated turning the differential around so it was facing the rear of the car and directly mounting the motor to it. It seemed like too much of an engineering hassle though. Mounting the diff would be difficult, and a FWD tranny would require some major hacking to get in the back of a Z. It would also be possible to get a "transwarp" motor which just a normal motor with a slip yoke instead of the shaft. This allows you to connect straight to the driveshaft and mount the motor in place of the transmission. The engine bay would be totally free for batteries this way too.

A few EVs have been made with automatics, but its not a popular choice. An auto needs to idle to keep the fluid pressure up, and the fact that motor's don't idle is a big benefit (in my mind), but there is no reason they can't. Also total transmission efficiency is lower, and you barely ever need to shift anyhow.... And CVTs are cool, but inefficient. I did see plans for an EV that used a CVT instead of the expensive (and most likely components to break) motor controller. Instead of the controller regulating voltage/amperage, you just applied full voltage to the motor and used the pedal connected to the CVT to control speed (and therefore amps). I don't know if that made any sense, but I think that is a very cool idea. I'd like to build something using that concept (maybe a dune buggy) because it would cost half as much without the controller, but I need to find a CVT that has a manual control cable first.

As fas a wh/lb goes lithium are unbeatable, I attempted to buy several thousand 18650 cells not that long ago to do the same thing, but the deal fell through. The amount of man hours needed to build a pack of sufficient size is huge, don't underestimate the amount of effort required. I'd definitely go lead acid at first. You'll get a few years to work the lithium angle, and prices are always coming down. I don't have a flywheel, partially for that reason, more inertia coupled with the motor. I can't say how it effects shifting, but it does seem like it would take longer for the syncros to change match the motors speed. Seems like the last 3 are even less important the first. It seems like you really only need 2 and 3, though 1st is nice to have for very steep grades/very slow speed. Direct drive does sound interesting. I bet the ~5% parasitic loss difference would end up being more noticeable than the ~50lbs of weight difference, together they would probably be significant. But that gain in efficiency at cruise is offset by a loss at low speeds.

I don't have the spedo hooked up, but it pulls so hard i've probably hit 50 in that little parking lot i've been testing it out in. I can't begin to tell you guys how much fun it is. I used to think it was a fast car in stock form, now its almost silly. I used to be able to chirp the tires in a straight line, now I can roast them. Careless - why wait? Sounds like your dad knows everything needed to build an EV. I think most starter motors operate at lower voltages than most street vehicles, but their operation is the same. There are lots of EV suppliers, though I got my motor on ebay actually. NetGain makes several sizes that appear very solid, if anything happens to my motor I'll probably switch to one of theirs. Gollum - That thing is a beast! Their curve ends at 450 amps but that is just a fraction of what it can handle. At 1000 amps you're talking like 280 ft/lbs! At 2000 Amps..... Just $4000....hmm....

Thats it, its suprisingly easy to do. If your going down a gear you just blip the throttle and ease it in, it will shift when you get the rpms right, pretty similar for upshifting. You let the synchros do the work, but the motor is very light and doesn't have alot of intertia so they can match its speed easily. It doesn't put nearly as much stress on the tranny as trying to do the same thing with a full engine attached.

Sure, generally larger batteries can put out more amps, or the same amps for longer period of time. For a strictly drag race only vehicle you could use a pack of lightweight high amperage batteries for short blasts down the track. The batteries white zombie uses I believe are 16lbs each.

The motor draws less amps in first. It uses the same amount of power total (volts x amps) but the amperage is higher (and the voltage lower) in a higher gear so the motor would produce more heat.

you can bolt on a flywheel, but I chose not to. Instead there is an adapter thamates the motor shaft and the transmission shaft.

I'm still working on the charger. In the fuel filler door there is going to be a male connector, you will just plug it in and it will go into recharge mode. I hope to charge at about 25 amps from a 240 line, maybe 15 amps from a 120v circuit. Its going to be a two phase system with the pack charging up to 90% quickly and then bulk charge will shut off and several intelligent smaller chargers will top each battery off one by one until they are each completely full. This way I can get back on the road quickly from a nearly empty pack, but when it is plugged in for longer periods (over night) it will do battery maintenance.

Electricity is about $.10 per kwh. My pack holds 10 kwh, so, $1 for a full charge. Let me see you drive 40 miles on $1 worth of gas. Here is a quick little video I took today while I was testing the motor mount. http://www.jumpcut.com/view/?id=CEEFB4120A8211DD8F60000423CEF5B0

No clutch, solid coupler from the motor to transmission. You don't need a clutch because you don't need to idle, when the car isn't moving the motor is simply off, plus pretty much all driving can be done in second. I saved quite a bit of rotating mass this way, and opened up a vent for air flow from the motor to exit the transmission.

I also think my tires will act like a "mechanical fuse" by loosing traction. If my motor is making 250ft/lbs but the tires break loose at anything over 175...then the transmission never "sees" more than 175. Right? I've heard it is good up until 250 or so. I've got a spare 5spd sitting here that I guess I'll hold onto for now, just in case.

I'm thinking its going to peak at 250 ft/lbs or so 400 is more the territory of twin motor / 2000A controller setups

A separate generator/alternator for regen braking would work, though it makes for a "messy" system. My motor has a shaft at each end, so I do have a point where I could attach a pulley that ran a load, perhaps with an electromagnetic clutch for on/off control to minimize parasitic drag. It would need to be pretty big, the 10,000 watt generator I have for the APU weighs 90 lbs and delivers 70 amps peak at 144 volts, which would probably take well over 30 seconds to slow the car down from 55mph to 10mph (this number is a complete guess, but probably accurate). Would still be usefull, I live in a very hill location so you could recover much of the energy used climbing a hill if you can spread the the regen recharge over a long period of time and not expect to come to a complete stop, just maintain a constant speed by adding load. Its such a cool concept to "take energy" out of your car's momentum, store it, and then turn it back into movement later. I'm going to try it with manual for now, but it is common for EVs to have a small vacuum pump installed for brake assist. I will add this if necessary. I'm hoping the weight out front wont make a big difference. The total weight of the front is about the same, but shifted a few inches forward. I could have but the batteries on their sides and had a taller pack that was more over the axle, but it came down to a trade off between body roll and steering response. I decided to go with the lower center of gravity. I will push it soon and see how it performs, but there are a few things I need to attend to first. I'm reinforcing the motor mount (I just learned that the motor may make even more torque than I thought, twice that of the stock motor) against twisting, and I need to attend to the rear brakes. One is dragging and the other is without shoes/drum at the moment. I may switch over to discs for simplicity, but they weigh more and I want to minimize rotating mass/unsprung weight.

Yes, the batteries are all in series for 144v. While not the most aerodynamic vehicle you will at least have a lot of capacity for batteries. Generally lighter vehicles are better but there is nothing wrong with a heavy one as long as you have a proportionately larger pack. Bigger GVW inflates the cost of the conversion because you'll need a larger motor and more powerfull motor controller to achive the same relative performance. You will probably need a fairly large genset for pulling loads and such, I'd guess around 20-30kw for any sort of long distance use. This would require a engine with around 60 hp constant output. The controller is from Logisystems, the motor was found on ebay, along with the wiring, battery lugs, shunts, contactors, etc. I had alot of patience, if I were to have been building it over a shorter timeframe I probably would stick to one of the several EV suppliers. One bank is definitely the way to go for simplicity and ease of balancing. For such a large vehicle I think you'd need a bank of around 24 6v flooded "golf cart" batteries. These are around 200+ amp hour generally so you'd have more than twice the capacity (~28kwh) vs my 10kwh. Pretty much everything you need to know is out there, you just have to dig through multiple sources to get a pretty complete picture. EVDL.org and EVTech Digest in particular are great resources. Any problem you might have has already been solved by someone else somewhere, better to learn from their mistakes than make them yourself (cheaper too). I'd be glad to help with any specific details you need as I've probably read every page/post/forum/article on EVs out there. I guess I'm a little obsessive.

I'm using a brushed DC system, whereas every production EV uses a AC induction setup. AC Advantages: Regenerative braking No brush maintenance Higher efficiency Higher RPM range (no transmission needed) Can be sealed from environment Can be water cooled AC Disadvantages: Waay more expensive Lower peak power Complex motor controller DC Advantages: Much higher peak power Waay cheaper Simple motor controller DC Disadvantages: Lower efficiency No regen braking Brush replacement every 100,000 miles Must be air cooled (brush dust needs to go somewhere) I can see why AC is the system of choice for production vehicles, and I'll admit that some of the benefits are very enticing, I really want regenerative braking for instance. But a DC system is still has so many advantages over a gasoline engine that the difference isn't worth the price difference in my mind. If you look at http://www.nedra.com/, the National Electric Drag Racing Association, all of the fastest electric vehicles in the world use DC systems.

The total system weight is about 850 lbs for batteries/motor/transmission I've seen the stock engine quoted at 600lbs. Plus I removed the gas tank, radiator, engine starting battery, and the rear spare, so the total weight is probably about the same. Lukaniuk - One charge should be good for about 40 miles on the highway, or 50+ miles around town at a lower speed. My commute is 25 miles each way, so with a short charge during class I can do 95% of all my driving gas free. (I've got plans for a small auxiliary generator when I need to make longer trips) There is a pack of 4 batteries in the rear to even out the weight distribution. That gaping hole is the future home of the generator. If I weren't going that route I could have put the rear batteries there and kept the car looking totally stock. I plan on making the generator a modular unit that can be easily removed and replaced with a second smaller battery pack for longer range, or, in the future a ultra high tech LiFePO4 pack for 100+ mile range.