Electric vehicle conversion...

[zmoz]

I know where there's a '66 mustang with a straight body for pretty cheap - no engine/tranny. I'm thinking electric car. :-) It would just be something for driving around town, under 55mph. I think stock the car weighs around 2500lbs, so probably more like 1800 without the engine/tranny/gas tank.

Few questions:

I don't know too much about electric motors. I know you need significantly less HP than a gas motor. How much less? Do you think this motor could get it up to 55 and keep it there?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=42922&item=3846273080&rd=1&ss



PageName=WDVW

(23 peak HP for 2 minutes, 10hp continuous)

Also, would it even need a transmission? I'm thinking I could hook the electric motor up directly to the rear axle...no?

[Tommy L]

Hi !

That idea looks great but I think the motor is too small, take a look at this link and under price list, there you can see the recommended motor for the weight of the vehicle.

http://www.kta-ev.com/

[bkrahmer]

First off, I think your curb weight is a bit light (3-400 pounds).  If you look at most electric cars, they are running in the 90-120V range.  Running large sets of batteries in parallel presents equalization problems, IIRC.  I think that motor is shy on voltage.  The power characteristics seem pretty good, though.  It might work with a good battery bank.  As far as transmission is concerned, I understand many people mate the motor to a manual transmission, and typically only use (first or second) and top gear.  It's possible to run direct-drive, but you may end up with slow acceleration with massive current draw that will shorten your range, or not being able to do 55.  I understand that AC motors lack this problem, but those motors, and moreso the controllers, are very expensive.

I was interested in building a hybrid electric some time back, but decided to build a house instead.    Almost have the roof on...

[veewee77]

That motor would not be powerful enough for a car.

Motorcycle, possibly but not a car.

Vivit elextroauto.com and check out motors and etc and you will likely decide not to convert that heavy a car.

DS

[richhagen]

Here are my thoughts, take them for what they are worth.  I have a small electric vehicle that is lighter than your mustang would be finished off.  It has a 12 Horsepower series wound GE motor in it which delivers more than 3 times the power of the motor you are suggesting.  I feel that my electric car is under powered.  You should look at a seperately excited, or series wound motor in the 15 to 20 HP range for a vehicle of that size for reasonable performance. You'll probably run a DC setup at about 144 volts or so as thats about as high as you can go without excessive brush wear on most of the commonly available motors built for this purpose.  You'll need a 600 Amp or better motor controller (I've heard of folks who have burned up 400 amp controllers in similar sized vehicles), and some sort of transmission to get the appropriate torque to your rear differential. While it would be a neat project, it is also a pretty big one.  Then when your done, you'll get to build your very own 'wind farm' to keep the batteries charged. Figure at least 500 amp hours at 12 volt generation with a light daily commute.  :-)

Rich Hagen

[Volvo farmer]

Here's what I would do. Buy the car (if it is truly cheap), drop a used 289/302/350 and tranny into it, then take it to a place where '66 Mustangs sell for a premium (The rust belt and LA come to mind). If you can do this for less than $2K I think you might be able to triple your money and come home. Take the profit and buy the lightest weight car frame you can find out of a junkyard and go from there. My local scrapyard had a really cool little Italian job laying around recently, rear engine about the size of a Harley motor and physically the same size as an old Mini-Cooper. That is just what you want in an EV. Weight is everything when trying to push thes things wih 20Hp motors. Just my opinion.

[thunderhead]

As I understand it, the electric motor needs to deliver the same HP as the petrol one, if you want the same performance.  It's about turning the wheels, and the wheels don't care if the thing turning them is petrol or electric.

If you don't want a transmission (quite possible) you need to calculate the ratio of the rear diff and the size of the wheels, and work out what the top speed is.  You also need to work out the torque you want when the lights go green.

For acceleration and hill climbing, weight is important (acceleration is torque divided by weight divided by wheel radius) but for speeds of 55mph, air resistance will dominate over weight.

For what you're describing, I'd want a much bigger motor than that.  I think maybe 50hp to 100hp, and if your car weighs a ton, your diff ratio is 3 and your wheels are 12" radius, maybe a stall torque of 200Nm and a top speed of 9000rpm.

The stall torque is based on a road force of 2000N, and the top speed is based on 55mph = 3000rpm on the wheels.  2000N on a one-ton car will give you adequate but not amazing performance.

You might find this website helpful:-

http://www.metricmind.com/

Good luck.

[nothing to lose]

Thanks for the links you guys posted, I will be checking those also myself. I am getting great deals on some small cheap cars like Dodge shadows with manaul trannies and bad engines if I want them.

"As I understand it, the electric motor needs to deliver the same HP as the petrol one, if you want the same performance.  It's about turning the wheels, and the wheels don't care if the thing turning them is petrol or electric"

That's not really correct. Belts, altenator, water pump, airpumps for smog, airconditonair, power steering, (did I forget anything) all take HP away from the tranny and wheels. Eleminate all the above items and you don't need the HP that drives them, and you do away with all that stuff when you go electric. I don't know how many horses that actually is, but I am sure it's at least 10hp or more those items use themselfs, though just  really geussing.

 As for the power steering, I drove a 88 Dodge Shadow for along time without it. It was a nice tight stiff steering, gave it a sporty feeling and I actually liked it that way. Was not too hard to steer either, but the wife wanted the power steering so I fixed it for her. I think most newer small cars are using that type of rack and pinion now and it works fine without power. Older cars like that Mustang may not have power to begin with and no problem, but if it had power then it's probably gonna need something or be a bear to steer.

Personally I agree about fix up the car original and go with somethng else for electric.

[thunderhead]

Belts, altenator, water pump, airpumps for smog, airconditonair, power steering, (did I forget anything) all take HP away from the tranny and wheels.

They also take HP away from the batteries in an electric vehicle.  

You might need a water-pump, depending on the motors you use: the Siemens motors are water-cooled, for example.

If you want an air-conditioner, the compressor will have to run off the batteries.

If you want power steering, you'll need to run an oil-pump off the batteries.

If you want power assisted brakes, you'll need to run a vacuum pump off the batteries.

I'm not sure what your airpump for smog does, but a windscreen demister will also draw power, and so will the lights.  You'll need an invertor to turn battery voltage into 12v for these things.

However, the electric motor that pushes the car down the road will be separate to this.  Car horsepower figures for conventional cars are based on rolling road tests, which also are independent of the auxiliary load, since they are measured at the driven wheels.