Lukaniuk Posted April 16, 2008 Share Posted April 16, 2008 Did you ever consider using something like a FWD tranny and mounting the motor in the back? That way you would have more room under the hood to mount the batteries lower and farther back. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 16, 2008 Author Share Posted April 16, 2008 wouldnt a automatic or even an CVT transmission work on an engine like that i know youd need a tranny cooler and a T converter but is it doable ? 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. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 16, 2008 Author Share Posted April 16, 2008 Did you ever consider using something like a FWD tranny and mounting the motor in the back? That way you would have more room under the hood to mount the batteries lower and farther back. 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. Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 16, 2008 Share Posted April 16, 2008 Since you're only using 1st and 2nd your cruise transmission ratio is 2.197. Going direct drive you'd need at least a 7.xx+ rear diff to get close to the final ratio you currently have with 2nd gear. I like the idea of direct drive, but it seems it might be a bit too much stress long term on the motor correct? I also just love the idea of having the entire motor in the trans tunnel. Open up the hood - "What motor?". Weight placement would be pretty good. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 16, 2008 Author Share Posted April 16, 2008 Since you're only using 1st and 2nd your cruise transmission ratio is 2.197. Going direct drive you'd need at least a 7.xx+ rear diff to get close to the final ratio you currently have with 2nd gear. I like the idea of direct drive, but it seems it might be a bit too much stress long term on the motor correct? I also just love the idea of having the entire motor in the trans tunnel. Open up the hood - "What motor?". Weight placement would be pretty good. 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. Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 16, 2008 Share Posted April 16, 2008 Ok, so who's gonna be the first to put twin 11 inch transwarp motors in their Z?.... Almost sounds as yummy as twin VG30E motors... Range won't be as good with the electric though. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 16, 2008 Author Share Posted April 16, 2008 Ok, so who's gonna be the first to put twin 11 inch transwarp motors in their Z?.... Almost sounds as yummy as twin VG30E motors... Range won't be as good with the electric though. 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 Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 16, 2008 Share Posted April 16, 2008 yup... enough to take on nearly anything that rolls up on you and beating them with a nearly silent motor. If that's not sleeper I don't know what is. The battery weight still kills ya. The two 11 inch motors should be under 500 pounds, but you're looking at another 500+ pounds of batteries in order to keep those motors turning for a decent amount of time. That's a 1000 pound power plant... not very light. Quote Link to comment Share on other sites More sharing options...
Wedge Posted April 17, 2008 Share Posted April 17, 2008 Erlier tonight on TLC their was a show that built an electric 69 camaro for the lead singer of Red hot chili pepper in california . Quote Link to comment Share on other sites More sharing options...
Silver Mine Motors Posted April 17, 2008 Share Posted April 17, 2008 Earlier you were talking about using a generator to charge the batteries for long distance driving. How much gas do you think the generator would use in order to charge the batteries in your car (when the car is just sitting)? And then let’s say you’re just driving and you run out of battery power and you decide to turn on the generator. How much gas would it be using as you drive down the freeway? I know these are questions that you won’t have a sure answer but I would just like to know your educated guess. Keep up the good work though. This is VERY interesting!!!!!!! Quote Link to comment Share on other sites More sharing options...
jmead Posted April 17, 2008 Author Share Posted April 17, 2008 Earlier you were talking about using a generator to charge the batteries for long distance driving. How much gas do you think the generator would use in order to charge the batteries in your car (when the car is just sitting)?And then let’s say you’re just driving and you run out of battery power and you decide to turn on the generator. How much gas would it be using as you drive down the freeway? I know these are questions that you won’t have a sure answer but I would just like to know your educated guess. Keep up the good work though. This is VERY interesting!!!!!!! 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... Quote Link to comment Share on other sites More sharing options...
Careless Posted April 17, 2008 Share Posted April 17, 2008 That's a 1000 pound power plant... not very light. lets face it. even a 5000lbs car with 1200 ft lbs of torque and some high RPM will "git" pretty good! Quote Link to comment Share on other sites More sharing options...
Silver Mine Motors Posted April 17, 2008 Share Posted April 17, 2008 so you would need 3/4 of a gallon of gas to run the generator for enouph time to fully charge your batteries. and once the batteries are charged you can drive 65 miles on them. so you'r basically doing 65 miles with 3/4 of a gallon of gas? Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 17, 2008 Share Posted April 17, 2008 Hmm... if these numbers add up, does this mean we could do around 70 miles to the gallon without ever plugging it in? Ok, for some reason a part of me doesn't want to believe it'd really be that efficiant, because if so we could reduce the battery weight significantly and just run it mostly off a generator and still get insane milage, and the distance able to be traveled would compare or BEAT the average car. You'd only need a 5 gallon tank to give you a significant range, and reducing the battery size would help offset the weight of the generator and gas tank. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 17, 2008 Author Share Posted April 17, 2008 so you would need 3/4 of a gallon of gas to run the generator for enouph time to fully charge your batteries. and once the batteries are charged you can drive 65 miles on them. so you'r basically doing 65 miles with 3/4 of a gallon of gas? 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. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted April 17, 2008 Share Posted April 17, 2008 I would think you could get a lot of efficiency by running a diesel engine at its peak efficiency into a generator turning its peak rpm which in turn would supply the propulsion. Pretty much eliminating batteries entirely except for quick bursts. I guess that is what you guys are trying to get at though. How much does a diesel generator weigh? Quote Link to comment Share on other sites More sharing options...
jmead Posted April 17, 2008 Author Share Posted April 17, 2008 Hmm... if these numbers add up, does this mean we could do around 70 miles to the gallon without ever plugging it in? 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. Ok, for some reason a part of me doesn't want to believe it'd really be that efficiant, because if so we could reduce the battery weight significantly and just run it mostly off a generator and still get insane milage, and the distance able to be traveled would compare or BEAT the average car. You'd only need a 5 gallon tank to give you a significant range, and reducing the battery size would help offset the weight of the generator and gas tank. 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. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 17, 2008 Author Share Posted April 17, 2008 I would think you could get a lot of efficiency by running a diesel engine at its peak efficiency into a generator turning its peak rpm which in turn would supply the propulsion. Pretty much eliminating batteries entirely except for quick bursts. I guess that is what you guys are trying to get at though. How much does a diesel generator weigh? 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. Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 17, 2008 Share Posted April 17, 2008 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. I was thinking from a weight stand point. I totally understand and agree with your reasoning to keeping it 100% electric only most of the time, for those that want to either keep the weight down or travel farther distances a generator would give you a great range with possibly better effiency than a similarly powered petrol engine. Quote Link to comment Share on other sites More sharing options...
jmead Posted April 17, 2008 Author Share Posted April 17, 2008 I was thinking from a weight stand point. I totally understand and agree with your reasoning to keeping it 100% electric only most of the time, for those that want to either keep the weight down or travel farther distances a generator would give you a great range with possibly better effiency than a similarly powered petrol engine. 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. Quote Link to comment Share on other sites More sharing options...
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