# DIY Electric sports car



## dougingraham (Jul 26, 2011)

CamoKing88 said:


> 1. Motor- I want a fast car so a big motor is a given. Can I find something big enough out of a forklift to do something with? What can I do to increase performance after getting it? Estimated price (USD) and places online that sell them?


I don't think you are going to be able to effectively use a stock forklift motor to make a high performance sports car. If you look at the Netgain motors, they originally were forklift motors but have been upgraded over the years as things needing improvement were found. Today these make excellent sport car motors. I would use a WarP 11 HV motor. This motor will give you the most performance with a 288 volt minimum pack.



CamoKing88 said:


> 2. Batteries- I'm looking at Lithium Ions because they are supposed to be the best right now, can anyone direct me to a post about making up a battery pack? So far I've found nothing. Also, I want to hopefully have 100 mile range, does this seem doable with such a small car and a big motor?


100 miles is at the upper end of range for a performance build. The vehicle could be a little on the heavy end with a range of 100 miles. This is not an unreasonable range but you will need to drive conservatively to get there. Driving like a drunken teenager will shorten the range considerably. 



CamoKing88 said:


> 3. Controller- I want to DIY this. So far I only found the 500Amp DIY kit, can I do something to maybe double this output since that would lead to better performance? If not, any good budget controllers?


500 amps is only one limit. The voltage is the other limit for the DIY controllers. If you want performance you need to be able to do both voltage and current. Higher voltage gives you a wider torque band and higher power. Amps is directly proportional to torque. If you are thinking about sports car performance you are going to want lots of torque and you want that torque band to be wide. You will probably want one of the professional controllers like a Soliton 1 or a Zilla HV. With an Warp11V and a battery pack that will deliver 1000 amps and at a sagged voltage of 288 volts you would be looking at a peak power level of 288kw (386hp) into the motor with wheel horse power of probably around 70% of that (270hp and 202kw). The other option is the Netgain controls product but I am reluctant to suggest that due to recent issues some forum members have related.

You will probably want to refine your mission and nail down your budget. I am expecting that your batteries will be around $10k to meet your 100 mile range. The motor and controller will be combined around $5k. This should result in a car capable of sub 5 second zero to 60 times with a top speed of well over 100mph.

Best wishes!


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## Duncan (Dec 8, 2008)

Hi Camo

_If you look at the Netgain motors, they originally were forklift motors but have been upgraded over the years as things needing improvement were found. Today these make excellent sport car motors. _

The only problem with this is - what have they done?
Coat of paint - check
Advance the brushes (Easy to do as DIY) - check
What else??? - nothing, possibly use different brushes (Easy to do as DIY)

So you will need a forklift motor

You will need a decent controller - if you can afford it a Soliton - otherwise wait for the next OpenRevolt

Batteries and range
$20K will not buy decent performance and 100 miles range
you will be able to have one or the other

If you drop your range requirements you enter a beneficial spiral - less weight - higher performance
Not to mention the problem of stowing all of those batteries in a small car


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## Frank (Dec 6, 2008)

Duncan, they have done a lot more than that! While the simple mods you listed will help any dc series motor, if they get used hard they will probably suffer more issues than a Netgain. 

Camo, keep researching, there is a lot of good info out there. Unless you're drag racing a lot of folks use lithium iron phosphate cells which can offer a reasonable compromise between power output and energy storage.


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## Duncan (Dec 8, 2008)

Frank said:


> Duncan, they have done a lot more than that! .


I would like to think so but so far nobody has been able to tell me 

*Possibilities
Better banding for higher Rpm*
Possibly but the Warp 11 is still only sold as a 4000 - 5000rpm motor
Just like a normal 11 inch

*Better bearings*
Don't believe it - forklift motors already have good long live bearings,
If open bearings are fitted they can be easily replaced with sealed ones

*Better Brushes*
This is a question of optimization - if optimized for higher currents they will wear like crazy an normal currents
Anyway I can change brushes

*Different gauge copper*
Again - thicker means less turns and less torque for a given current
Don't see any improvement here

So until somebody can point to an improvement I think the main change is a nice coat of red paint

Which makes that an extremely expensive paint job


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## dougingraham (Jul 26, 2011)

Duncan said:


> I would like to think so but so far nobody has been able to tell me


Since George Hamstra started out drag racing with these motors, the bulk of the changes were probably just to keep the internals from blowing up under the high currents. I doubt that there are any forklifts that can take 2000 amps for even a few seconds. There certainly aren't any forklift motor controllers that can do that. And looking at the differences between a motor that can take 500 amps for a few seconds and one that can take 2000 amps for a few seconds you would not see much of a difference. They would look pretty much the same to the untrained eye. The question you need to ask is if you need to be able to do 2000 amps in a daily driven street car. I have my Soliton 1 set to 1000 motor amps and I hit that for a few seconds at a time every time I drive. I will have 3000 miles on the motor sometime this weekend and I can see the comm is still shiny with the proper patina where the brushes make contact.

A better motor to look at would be the WarP 11HV with the interpoles. Forklifts don't run 288 volts at 1000 amps. This motor can, at least for a little while. The same is probably true of the other motors. In a forklift they typically don't run voltages over 96. So even with the WarP9 being specced at 172 volts this is quite a bit more than your typical forklift.

All that being said, it looks like you could probably make these motors at a cost of around $500 if you tooled up to make 10000 units. I would be somewhat surprised if there isn't an inexpensive Chinese motor that could be repurposed for EV's. You just have to find it and then manage to get the price the large industrial customers are paying.


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## Frank (Dec 6, 2008)

http://www.go-ev.com/Next_Gen.html


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## Duncan (Dec 8, 2008)

dougingraham said:


> Since George Hamstra started out drag racing with these motors, the bulk of the changes were probably just to keep the internals from blowing up under the high currents. I doubt that there are any forklifts that can take 2000 amps for even a few seconds. There certainly aren't any forklift motor controllers that can do that. And looking at the differences between a motor that can take 500 amps for a few seconds and one that can take 2000 amps for a few seconds you would not see much of a difference. They would look pretty much the same to the untrained eye. The question you need to ask is if you need to be able to do 2000 amps in a daily driven street car. I have my Soliton 1 set to 1000 motor amps and I hit that for a few seconds at a time every time I drive. I will have 3000 miles on the motor sometime this weekend and I can see the comm is still shiny with the proper patina where the brushes make contact.
> 
> A better motor to look at would be the WarP 11HV with the interpoles. Forklifts don't run 288 volts at 1000 amps. This motor can, at least for a little while. The same is probably true of the other motors. In a forklift they typically don't run voltages over 96. So even with the WarP9 being specced at 172 volts this is quite a bit more than your typical forklift.
> 
> All that being said, it looks like you could probably make these motors at a cost of around $500 if you tooled up to make 10000 units. I would be somewhat surprised if there isn't an inexpensive Chinese motor that could be repurposed for EV's. You just have to find it and then manage to get the price the large industrial customers are paying.



Couple of things
(1) 288v and 1000 amps
The voltage is determined by the rpm - the only way you can reach 288v (motor) is by having about 270v back EMF - which implies a very high Rpm
So the whole voltage argument is moot 

(2) My forklift motor is designed to take 200 amps continuous (1 hour rating) so 2000 amps for a few seconds is not a problem - 


I have read the thread that Frank referenced
All good improvements - BUT
They are either something I could do for myself OR they are minor

The only one that would be really useful would be the improved banding 
and again that is only useful if you are going to use higher Rpm's

On the other hand those motors all have
_shaft are 1.125" in diameter with a 1/4" keyway_

That is a big negative

As an engineer with nearly 30 years of experience I MUCH prefer the splined shaft on my Hitachi forklift motor


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## Yabert (Feb 7, 2010)

After playing with Warp and Advanced DC (EV type motor) compare to GE and other forklift motor, I'm sure than some forklift motor can do good EV motor after some modification.


Duncan said:


> On the other hand those motors all have _shaft are 1.125" in diameter with a 1/4" keyway_
> That is a big negative


+1 ont this one.
This tiny standard shafts diameter is probably related to the old time when the 500A controllers was considered powerful...


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## dougingraham (Jul 26, 2011)

Duncan said:


> Couple of things
> (1) 288v and 1000 amps
> The voltage is determined by the rpm - the only way you can reach 288v (motor) is by having about 270v back EMF - which implies a very high Rpm
> So the whole voltage argument is moot


Looking at the dyno plots for the WarP 11HV you would need 288 volts at 500 amps to hold 5000 RPM. 5000 RPM is reasonable and hardly what I would call a very high RPM. Looks like it would be around 4500 RPM at 1000 amps and 288 volts.


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## Duncan (Dec 8, 2008)

dougingraham said:


> Looking at the dyno plots for the WarP 11HV you would need 288 volts at 500 amps to hold 5000 RPM. 5000 RPM is reasonable and hardly what I would call a very high RPM. Looks like it would be around 4500 RPM at 1000 amps and 288 volts.


Please send me a link to your dyno plot
The only plot I can see has less than 100v back EMF at 5000rpm

This means that I could drive a 288v motor to over-speed destruction at 1000 amps and less than 150v

Besides the argument is moot -
If Warp have created a motor which requires a very high voltage to perform the same as a standard motor at a much lower voltage - why is that relevant to somebody with a more sensible motor?

The controller modulates the motor voltage to achieve the desired current,
You need 10% MORE current on the HV motors to achieve the same torque so you can't even drop the size of the motor cables

http://www.evsource.com/tls_warp11.php

Thinking about it
Power = Volts x Current and also Rpm x Torque
So as I need more current for a given torque (on the HV motors)
For the same power output (Torque and Rpm)
Unless the efficiency is MUCH worse I will need LESS voltage - not more!

I just don't see how I can apply an actual 288v to any of these motors and have them survive

Back EMF + Voltage to drive current = Motor voltage
1000 amps is about 15v - so we need 273v, Back EMF = 10,000rpm +

The Inter-poles are a great idea - but the effects (As far as I know) is to make the motor have a constant efficiency

My motor with advanced timing shows a noticeable increase in torque (at a constant 500 amps) as the motor rpm rises towards the optimum

A Motor with inter-poles should have that additional efficiency across the speed range 

None of which actually translates into an increased voltage capability


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## dougingraham (Jul 26, 2011)

Duncan said:


> Please send me a link to your dyno plot
> The only plot I can see has less than 100v back EMF at 5000rpm


WarP 11 HV dyno graph

At 72 volts with a 500 amp load the RPM is 1250. Torque at 500 amps is about 143 ft-lbs which is higher than a WarP9. I believe torque at 1000 amps is a little over 300 ft-lbs. At 500 amps and 288 volts RPM should be close to 5000. And not too much less than that at 1000 amps.

I wish there was a version of this graph that went out to 1000 amps.


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## Tesseract (Sep 27, 2008)

Duncan said:


> Please send me a link to your dyno plot
> The only plot I can see has less than 100v back EMF at 5000rpm
> 
> This means that I could drive a 288v motor to over-speed destruction at 1000 amps and less than 150v


I wrote a post here a long time ago - I leave it up to the interested to search for the original - that more or less said that the WarP-9 requires 50V per 1000RPM at 1000A. This is in the saturated operation part of the curve so RPM is linearly proportional to voltage and torque is linearly proportional to current (below saturation - around 200-300A - both are square functions).

I don't have data on the 11HV but my understanding is that it has more turns on each field pole so it *should* produce more torque for a given current and require more voltage for a given RPM.



Duncan said:


> A Motor with inter-poles should have that additional efficiency across the speed range
> 
> None of which actually translates into an increased voltage capability


Wrong on both counts - interpoles don't actually improve motor efficiency - they are another I²R loss term, actually - they just improve commutation performance at high currents by producing a field that counteracts "armature reaction".

By improving commutation (literally reducing the voltage difference between adjacent commutator segments) the motor can tolerate a higher voltage at a given current (or, conversely, a higher current at a given voltage, but with the caveat that interpoles do not improve the heat dissipation capability of the motor...).


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## albano (Jan 12, 2009)

Frank said:


> http://www.go-ev.com/Next_Gen.html


If your brushes cover 2/3 of your com segments, there no need to go thicker brushes...but different grade I agree and still you have to find out the right grade for your motor app.

You can't beat old forklift motor that has "steel V rings" on com... now a days you hardly find it on new motors. 

I think they had more com segments to handle more voltages.

Old forklift motor still rule as to prove just look at "rocket drag bike" from Shawn Lawless that does 6's on 1/4 miles that was ounce Dennis Berube's motor...and that motor was original from 24V forklift motor with steel V rings and it never burnt any com or field cause of use the right grade of brushes.... 

Remember it was from 24V and now running 355V.....and 4000A. The secret of this motor remain in Dennis head!


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