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jmead

Electric 240z Project Pics

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I hear ya.

I think I drove a total of 50 miles all last week. I could probably get by with a lot less batteries.

Great now I have to finish my EFI intake manifold and build an electric Z

 

Derek

 

if I had the money and time I would SO build an electric Z. I really don't drive too much. considering I live NEXT DOOR to work. So really i only would be driving like 10-20 miles TOTAL a day.

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The problem I've been seeing, reading and heard about with the DEKA or other AGM small case batteries is that you need more of them to equal the same reserve capacity of a larger case battery, even though the instant discharge rate might be the same or close. This would work well for a short run, high rate of accel car like a drag racer, but not for distance like we want.

 

The guy that is or will be helping me, has been looking into using Li/ion batteries in the AA or AAA size, which we will then place into our own cases, replaceable as modules.

I'm likely going to start with conventional batteries to get it going and then switch out later, once the initial cost of conversion is dealt with. :shock:

 

jmead;

 

I'm more interested in the choice to use the tranny, especially without the clutch. I've held onto my clutch for now, because I figured it would be easier to drive with, especially while down shifting. I can drive no problem without using the clutch, but still need to work on my clutchless down shifting, I would imagine this would be more difficult (for me) than with a gas engine, since I'm used to the rate of decay or RPM on a gas engine, especially with a heavy flywheel, with just the coupler, the rate of decay should be higher, making that time to slip into the lower gear shorter.

I'd rather run without a clutch, since that's added weight that will eat power, on accel, but may help once your rolling along.

 

I'm even considering doing away with the tranny, and going with a taller gear, to save weight, but I'm not sure how towing will be effected by this. Hmmm, removing 1st and 2nd gear, and leaving only the last 3 gears for towing accel and cruising may be an option.

 

Thoughts?

 

I saw something on tv called "Future car part 1-4"...I think one of the guys there said that laptop batteries are the best, because there are light and can withstand a lot of abuse...Downside, they are expensive..

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I saw something on tv called "Future car part 1-4"...I think one of the guys there said that laptop batteries are the best, because there are light and can withstand a lot of abuse...Downside, they are expensive..

 

That seems to be the problem...

 

Plentful and cheap, but heavy and/or low storage capacity

 

OR

 

Good storage capacity, light but expensive.

 

:(

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The guy that is or will be helping me, has been looking into using Li/ion batteries in the AA or AAA size, which we will then place into our own cases, replaceable as modules.

I'm likely going to start with conventional batteries to get it going and then switch out later, once the initial cost of conversion is dealt with. :shock:

 

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'm more interested in the choice to use the tranny, especially without the clutch. I've held onto my clutch for now, because I figured it would be easier to drive with, especially while down shifting. I can drive no problem without using the clutch, but still need to work on my clutchless down shifting, I would imagine this would be more difficult (for me) than with a gas engine, since I'm used to the rate of decay or RPM on a gas engine, especially with a heavy flywheel, with just the coupler, the rate of decay should be higher, making that time to slip into the lower gear shorter.

I'd rather run without a clutch, since that's added weight that will eat power, on accel, but may help once your rolling along.

 

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.

 

 

I'm even considering doing away with the tranny, and going with a taller gear, to save weight, but I'm not sure how towing will be effected by this. Hmmm, removing 1st and 2nd gear, and leaving only the last 3 gears for towing accel and cruising may be an option.

 

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.

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Careless - why wait? Sounds like your dad knows everything needed to build an EV.

 

My father and I only recently started to get along, and only now is he seeing that all the funky stuff I talk about or I'm interested in is stuff that I can see becoming a life-long passion or side-career.

 

He thought I was gonna bring home a pile of junk when I said "87 300zx Turbo" because

 

it was an 87, like his rusty 87 jetta...

it was a 300zx, which is synonymous with our old neighbor's expensive z32, so 1700 bucks SURELY cannot mean good things,

and because it was a Turbo, and Turbo also means expensive to him.

 

But when I brought it home, he was the one to drive it into the garage, and he took it around the block. I think he fell in love... so it's something that I'm sure he'd be open to.

 

Just gotta justify doing it. Only way is break the current engine :icon43:

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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.

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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.

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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.

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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.

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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

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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.

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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!!!!!!!

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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...

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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.

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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.

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