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Electric Car Conversion

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DougoMan

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I was watching Choppers on Discovery last night, and those crazy guys put an electric engine in a motorcycle.

Running the prototype build, they almost broke the world record for the 1/4 mile. That is the kind of power these things generate.

Anyone familiar with a good guide to doing an electric-car conversion?

The hardest part (I imagine) would be getting it to work with a transmission. The torque these generate could probably destroy anything rated for less than 500HP.

The biggest problem Tesla had was with transmissions. They eventually went with a one speed.

We're done here. It's not worth the effort to try to bring this thread back.

Zenmervolt - AnandTech Moderator
 
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I've got a friend that has an old 2 door corolla that he's converted to electric. The thing has no storage space, the whole trunk is full of golf cart batteries, lol.

He's using the original corolla transmission without any problems. It's a manual transmission but because the motor free wheels when you aren't giving it power you can shift without the clutch. Sure, if you're trying to get as much power as possible out of it you'll run into problems but if you just want something to drive around as a normal car you can easily set it up so the transmission will last.

He's even chopped up an electric wall AC unit and hooked everything up so he's got good AC that comes out of the car's normal vents.
 
Bignate603 said:
I've got a friend that has an old 2 door corolla that he's converted to electric. The thing has no storage space, the whole trunk is full of golf cart batteries, lol.

He's using the original corolla transmission without any problems. It's a manual transmission but because the motor free wheels when you aren't giving it power you can shift without the clutch. Sure, if you're trying to get as much power as possible out of it you'll run into problems but if you just want something to drive around as a normal car you can easily set it up so the transmission will last.

He's even chopped up an electric wall AC unit and hooked everything up so he's got good AC that comes out of the car's normal vents.
Click to expand...

Sweet. That is cool that he got it working with the original transmission. I was thinking maybe it would be possible to write a computer program to decrease voltage while engaging the clutch. Sounds like he found a similar and simpler solution.

So he used golf cart batteries, eh? I'll have to look into those.

I was thinking of just wiring a shit load of lead-acid car batteries together. They are pretty cheap at Costco.


edit: This is only about $10,000 after rebate.

http://zapglobal.wordpress.com/2010/09/07/zap-electric-truck-and-van-qualify-for-federal-tax-credit/
 
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DougoMan said:
Sweet. That is cool that he got it working with the original transmission. I was thinking maybe it would be possible to write a computer program to decrease voltage while engaging the clutch. Sounds like he found a similar and simpler solution.

So he used golf cart batteries, eh? I'll have to look into those.

I was thinking of just wiring a shit load of lead-acid car batteries together. They are pretty cheap at Costco.


edit: This is only about $10,000 after rebate.

http://zapglobal.wordpress.com/2010/09/07/zap-electric-truck-and-van-qualify-for-federal-tax-credit/
Click to expand...
"Neighborhood Vehicle" speeds of up to 25 MPH! lookout!
 
I don't understand using the original tranny part. Trannies are needed because you want to keep the engine running at a rpm range but electric motors don't work that way. realistically you just need a polarity switch, and a limiter on reverse :biggrin: and off you go on the electric.
 
sdifox said:
I don't understand using the original tranny part. Trannies are needed because you want to keep the engine running at a rpm range but electric motors don't work that way. realistically you just need a polarity switch, and a limiter on reverse :biggrin: and off you go on the electric.
Click to expand...
yep. there is all the torque you need at low RPM, so you gear it accordingly.
 
DougoMan said:
Sweet. That is cool that he got it working with the original transmission. I was thinking maybe it would be possible to write a computer program to decrease voltage while engaging the clutch. Sounds like he found a similar and simpler solution.

So he used golf cart batteries, eh? I'll have to look into those.

I was thinking of just wiring a shit load of lead-acid car batteries together. They are pretty cheap at Costco.


edit: This is only about $10,000 after rebate.

http://zapglobal.wordpress.com/2010/09/07/zap-electric-truck-and-van-qualify-for-federal-tax-credit/
Click to expand...

Don't need a clutch.

Lead acid batteries are cheap, but they'll be useless after a few hundred cycles and are heavy.
 
JCH13 said:
Don't need a clutch.

Lead acid batteries are cheap, but they'll be useless after a few hundred cycles and are heavy.
Click to expand...

Shens

Just do not run it down, and it will work like your car battery.

The first CARS, (not first electric cars), were run on lead acid batteries.

Just get a shit load of them, wire them in a series for god knows how many volts and you will have a screaming electric car. Just don't run the battery down a lot.


edit:

just so I do not get criticized, I do mean wire them all in a series.

Wire however many you need (x) times 12 volts to get the voltage you want.

Then do that at least 10 times in parallel.

So yes, you will need 100s of batteries. Most likely you will want to tow the battery pack.

The design I always imagined is a truck bed full of batteries pulling a trailer full of batteries.


edit 2: i found a sweet deal on a '91 AWD BMW 3 series. That would be an awesome car for the conversion.

I would like to have the transmission, just to have the fun of shifting. You could always start out in 5th gear if u wanted to.

Also, it will be safer to drive in neighborhoods in a lower gear.
 
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desy said:
No in the EV community its commonly known lead acid aren't the best but they are the cheapest, its why golf cart batteries are preferred because they are designed to cycle more often and even though its lead acid the plates are designed thicker which is why you only get 6 v in the same pyhsical space.
There are tons of good EV articles
http://www.nuauto.com/1532/sourcing-batteries-for-ev-vehicle-conversions/
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Ok, I see what you are saying. It is a better technology if you want to save weight and run the batteries all of the way down.

For total usable power though lead acid is cheaper.

They will also be under warranty for 60,000 miles, or four years ;-)

Hehehehe.
 
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DougoMan said:
Ok, I see what you are saying. It is a better technology if you want to save weight and run the batteries all of the way down.

For total usable power though lead acid is cheaper.

They will also be under warranty for 60,000 miles, or four years ;-)

Hehehehe.
Click to expand...

Walmart return dept

DougoMan:Hi I would like to do some warranty claim for my car battery.

Service Rep:sure thing, where is the battery.

DougoMan: Err, can you send someone to help me out? I have 48 sitting in my truck...
 
sdifox said:
Walmart return dept

DougoMan:Hi I would like to do some warranty claim for my car battery.

Service Rep:sure thing, where is the battery.

DougoMan: Err, can you send someone to help me out? I have 48 sitting in my truck...
Click to expand...

Just do 1 every week... :awe:
 
sdifox said:
Walmart return dept

DougoMan:Hi I would like to do some warranty claim for my car battery.

Service Rep:sure thing, where is the battery.

DougoMan: Err, can you send someone to help me out? I have 48 sitting in my truck...
Click to expand...

Maybe this is why he needs a 20ton towing capacity?
 
sdifox said:
I don't understand using the original tranny part. Trannies are needed because you want to keep the engine running at a rpm range but electric motors don't work that way. realistically you just need a polarity switch, and a limiter on reverse :biggrin: and off you go on the electric.
Click to expand...

Not true.

First, you figure out how much torque you're going to need.

Next, you need to start looking at transmissions and motor combinations that can give you that torque. Ideally, you want to go as small as possible on the electric motor. After all, minimum weight is a good thing because you're saving power.

Those electric motors have torque and amperage curves that you can look up. There is a point of maximum power, just like a gas engine: the best torque at the best power usage is a compromise of both. Ideally, you'd like the smallest electric motor that can give you the maximum torque you need paired with a continuously variable tramission that will keep you at your max power point. Lacking that, a shifting transmission will do, but you will have an RPM range rather than a more effective single point.

Yes, electric motors have all their torque down low. That is also the point at which they are stalled, and are drawing maximum amperage. That's something to avoid if you can because it is extremely hard on the motor and your breakers - depending on how you're set up.
 
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DougoMan said:
Ok, I see what you are saying. It is a better technology if you want to save weight and run the batteries all of the way down.

For total usable power though lead acid is cheaper.

They will also be under warranty for 60,000 miles, or four years ;-)

Hehehehe.
Click to expand...

If by total usable power you mean voltage when fully charge, yes lead acid will be cheaper. If by total usable power you mean something that will give you the most range, deep cycle batteries are far better. To keep the lead acid batteries from dying quickly you'd only be able to use a fraction of the power they contain. My friend spent quite some time researching and building his conversion, to the point where he even constructed his own motor controller. If he could have gotten away with cheap batteries he would have.

Also, to get decent range even with the deep cycle ones you need a crap load of them. The engine bay is full of them and the trunk is full of them. There is literally no room left for any more batteries unless he started piling them in the back seat.
 
Pulsar said:
Not true.

First, you figure out how much torque you're going to need.

Next, you need to start looking at transmissions and motor combinations that can give you that torque. Ideally, you want to go as small as possible on the electric motor. After all, minimum weight is a good thing because you're saving power.

Those electric motors have torque and amperage curves that you can look up. There is a point of maximum power, just like a gas engine: the best torque at the best power usage is a compromise of both. Ideally, you'd like the smallest electric motor that can give you the maximum torque you need paired with a continuously variable tramission that will keep you at your max power point. Lacking that, a shifting transmission will do, but you will have an RPM range rather than a more effective single point.

Yes, electric motors have all their torque down low. That is also the point at which they are stalled, and are drawing maximum amperage. That's something to avoid if you can because it is extremely hard on the motor and your breakers - depending on how you're set up.
Click to expand...

I WANT TO SHIFT! I love doing it. And want to keep doing it.

And also I know it will be easier to hit 200 with a manual gearbox. Prove me wrong my friend. 200MPH or bust. That is the new name of this project.

Manual gearbox = way the fuck more efficient. Imagine running your gas engine with NO GEARS. WASTE OF ENERGY

Same with electric, I imagine. You could do a way smaller electric engine and have it be way easier on the tranny with a gearbox. I imagine a really small electric engine would do.

Just torn between doing a truck that is meant to tow (smart) or a BMW (cool).

I say BMW with small electric motor hooked to original gearbox with Lithium ion batteries.

Probably need to buy a Nissan Leaf and take out the batteries to do this. Or else I am leaning towards Red or Yellow top Optima Batteries.

Maybe I will do two cars for proof of concept:

1. BMW with Lithium Ion or deep cycle from Costco

2. Truck with shit load of lead acid batteries under warranty from Costco

Yes, I own stock in Costco.
 
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DougoMan said:
I WANT TO SHIFT! I love doing it. And want to keep doing it.

And also I know it will be easier to hit 200 with a manual gearbox. Prove me wrong my friend. 200MPH or bust. That is the new name of this project.

Manual gearbox = way the fuck more efficient. Imagine running your gas engine with NO GEARS. WASTE OF ENERGY

Same with electric, I imagine. You could do a way smaller electric engine and have it be way easier on the tranny with a gearbox. Man I imagine a really small electric engine would do.
Click to expand...

Fleabag? Is that you?

From this post I can tell that any attempt that you do to convert a car from gas to electric will be fraught with sweat, wasted money and tears.

Make sure to take some pictures 😀
 
As I work for a company that does quite a bit of battery research...

DIY Lithium Ion should only be done by an expert with substantial knowledge, if some things go wrong you could have a nice explosion on your hands.

Lead acid batteries are energy-dense, but not power-dense, you'll need a ton of lead-acid batteries to get the instantaneous power you need to reach 200mph. Though I seriously doubt you can find, or afford, electric motors capable of sustaining the power output that you need to reach 200mph.

Electric motors LOVE to operate at nearly their maximum speed for cooling and electrical efficiency reasons. If you operate an electric motor at peak-power for an extended period of time it is likely to fail unless you invest some serious cash into getting an oil-cooled motor.

Transmissions can be used, though skip the clutch and don't expect it to last very long. For example, a traditional transmission designed for 300hp can probably handle 300lb-ft of torque or so, a 300hp DC electric motor can probably put out damn near 1000+ lb-ft of torque. Any transmission that could handle that will be serious business in terms of both size and money.

Hooking a "really small electric motor" to a transmission just means that you're under-powering your vehicle. IC engines are geared because they have relatively low torque. An electric, particularly DC, motor has oodles of torque at low speeds, so theres no need for a transmission. A normal DC motor can have around 900% or more of it's peak-power torque at 0RPM, some AC motors can have up to 400%.

As for hitting 200mph... figure the Z06 is fairly aerodynamic, and with 400hp it could do 198mph if I'm not mistaken. You'll need your motor(s) to output at 400hp+ continuously to get there. Heat rejection from the motors will be a serious issue, heat rejection for your battery packs will be a serious issue, and total energy in your batteries might not even be adequate.

Making an electric vehicle to do 200mph can be done, though it will be a serious under-taking that will probably take quite a bit of money and probably years of development. Good luck.
 
JCH13 said:
Transmissions can be used, though skip the clutch and don't expect it to last very long. For example, a traditional transmission designed for 300hp can probably handle 300lb-ft of torque or so, a 300hp DC electric motor can probably put out damn near 1000+ lb-ft of torque. Any transmission that could handle that will be serious business in terms of both size and money.
Click to expand...

I'll have to ask my friend how he manages that with his car. He's spent some serious time on the motor controller. He's got one commercial one and one that he's built based on some plans from a forum he's a part of for electric vehicles. It's possible that he has it set up so that it limits max torque.
 
Bignate603 said:
I'll have to ask my friend how he manages that with his car. He's spent some serious time on the motor controller. He's got one commercial one and one that he's built based on some plans from a forum he's a part of for electric vehicles. It's possible that he has it set up so that it limits max torque.
Click to expand...

That's likely, it'd be as simple as current-limiting the motor. Though my point is that electrical motors hit peak efficiency at very high speeds, and have the low-speed torque to easily accelerate the car, making a transmission largely foolish.
 
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