# Motor for a Cooper Mini



## Jarrad (Oct 19, 2013)

Hi EV enthusiasts,

This is my first post on this site. I am a noob with EV conversions. I am considering converting a 2002 mini cooper on a budget.

I have found this forklift motor on ebay that may work for me because it is close to home.

http://www.ebay.ca/itm/Clark-fork-l...klifts_Other_Lifts&hash=item3f29dda72c&_uhb=1

I found another post here discussing these motors with this info:



major said:


> The MLV type Prestolite motor was a 36/48V lift pump motor (fork truck). It was rated for a 20% time-on 5 minute base duty cycle at somewheres north of 300A; maybe 350. Intended for intermittent duty. It would have a continuous rating of around 200A if ventilated with its internal fan. It was one of the most efficient laminations in the product line. So at 48V, 200A would have pumped out 10 horse continuous. That might have been around 3 kRPM. You could push that up with higher voltage and maybe get 20 hp but she'd be screaming at like 6 grand and probably run a bit hot.


I don't need the car to be overly sporty just a commuter. Would I be disappointed with the power from this motor?

Jarrad


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## major (Apr 4, 2008)

Jarrad said:


> Hi EV enthusiasts,
> 
> This is my first post on this site. I am a noob with EV conversions. I am considering converting a 2002 mini cooper on a budget.
> 
> ...


Electro-wise, it would do well for you, IMO. But it will have the pump shaft problem..... an internal spline drive. Difficult to couple to.


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## Jarrad (Oct 19, 2013)

It comes with the pump so I should be able to use the pump shaft to make the adapter plate. 

I work at a metal fabrication shop. More sheet metal but we do have a cnc mill and some decent lathes.


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## Jarrad (Oct 19, 2013)

I would like to have regenerative braking. I understand these motors need to have the brushes advanced for higher voltage. Will I be able to use this motor without the brushes advanced at 120 volts and get regen?


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## major (Apr 4, 2008)

Jarrad said:


> I would like to have regenerative braking. I understand these motors need to have the brushes advanced for higher voltage. Will I be able to use this motor without the brushes advanced at 120 volts and get regen?


This is a MVZ type Prestolite made a number or years after the MLV type of which I spoke previously. The older Prestolite pump motors had a factory brush advance and were unidirectional. This newer MVZ is unidirectional because it has only 2 terminals but I cannot tell whether it has an advance. Also, I strongly suspect it is series wound. So there is little (almost zero) chance you would be able to regenerate with it. You'd have to find a genius to build you a special controller  

You may in fact be able to run 120V battery, but motor voltage via the controller will certainly be lower. Determine that keeping RPM below 6000; under 5000 would be better.


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## Jarrad (Oct 19, 2013)

Is AC the best way to go if I want regenerative braking?


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## major (Apr 4, 2008)

Jarrad said:


> Is AC the best way to go if I want regenerative braking?


Pretty much the only way - yep.


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## Jarrad (Oct 19, 2013)

major said:


> Electro-wise, it would do well for you, IMO. But it will have the pump shaft problem..... an internal spline drive. Difficult to couple to.


You got that right. The shaft on this pump is only half an inch in diameter.


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## pm_dawn (Sep 14, 2009)

major said:


> Pretty much the only way - yep.


Well not really....

How about Permanent Magnet brushed DC motors.
Or SepEx motors......

I have a SepEx in my car and it does regen, almost all european electric cars from the early 90ies had that, like Renault, Peugeot, Citroen.

Regards
/Per


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## major (Apr 4, 2008)

pm_dawn said:


> Well not really....
> 
> How about Permanent Magnet brushed DC motors.
> Or SepEx motors......
> ...


You notice I qualified the statement with _pretty much_ instead of _absolutely_. The types of systems you mention, DCPM and SepEx, are pretty much unavailable to the typical DIYer, so what's the point? Maybe if he were doing a cart or bike, but where does he find that equipment for an EVcar?

Regards,

major


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## dtbaker (Jan 5, 2008)

Jarrad said:


> I would like to have regenerative braking. I understand these motors need to have the brushes advanced for higher voltage. Will I be able to use this motor without the brushes advanced at 120 volts and get regen?



why are you stuck on having regen braking (which means an AC motor/controller) for a build you say you want to do on a budget? As an engineer it is a drag to throw away the braking energy as heat, but economically, its less expensive to buy a little more battery capacity and go with brushed DC. An 8" brushed DC with a 300 or 400amp controller at 120v really is very drivable.... not fast, but not bad.

if you really want to keep cost down, consider a 8" DC motor and an inexpensive old school controller like a Curtis 1221c or 1231.... compared to price of AC motor + controller/inverter, which MAY extend your range 10%-15% with regen.


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## Jarrad (Oct 19, 2013)

Here are some photos of the motor. I have a plan to re-fabricate the motor end plate so I can extend the shaft with a collar using a larger bearing. I would like to know if this motor will be appropriate before proceeding.

I am planning to use a Zappi N2 120V 600A controller. (not with regen, but it is interesting to have the option)

1. Will this motor handle 600A starting current?
2. Is the speed limitation the bearing? (I could buy hybrid bearings and or add liquid cooling to the bearing.
3. Any ideas getting the fan off the shaft? (I'm thinking of a couple rods through the fins then press it out, but it is a flimsy casting)

Thanks for your help.


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## major (Apr 4, 2008)

Jarrad said:


> Here are some photos of the motor. I have a plan to re-fabricate the motor end plate so I can extend the shaft with a collar using a larger bearing. I would like to know if this motor will be appropriate before proceeding.


It appears to be the 33 slot(and comm bar) design which is very good and should work well in a small EVcar. You should give it a 5º brush advance.



> 1. Will this motor handle 600A starting current?


Yes.



> 2. Is the speed limitation the bearing?


No, the comm and the conductor bars are the speed limitation.



> 3. Any ideas getting the fan off the shaft? (I'm thinking of a couple rods through the fins then press it out, but it is a flimsy casting)


Be careful and heat the aluminum fan with a torch as you pull it off. The aluminum will expand and loosen.


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## Jarrad (Oct 19, 2013)

So should I just remove the 4 screws and drill new holes to give 5 deg advance? Should I replace the brushes?


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## major (Apr 4, 2008)

Jarrad said:


> So should I just remove the 4 screws and drill new holes to give 5 deg advance? Should I replace the brushes?


I suggest you drill and tap new holes in the steel frame tube. 

Looking at the brushes in the prior post pics, I'd get a replacement set. New springs also. And when you're doing the shaft work, indicate the comm and turn and undercut if needed. 

Or you can keep it simple (and cheap) for now and see how well it works for you before service and replacement parts


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## Jarrad (Oct 19, 2013)

The internal splined shaft is not going to be much of a problem at all. I was able to remove the splined insert so now I can just turn a new solid shaft and press into the motor shaft.


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## Jarrad (Oct 19, 2013)

Here's the coupling machined and attached to the flywheel. Not my most accurate work. The flywheel surface is out by about 6 thou. I think I will try it with the old clutch and have it ground and balanced when I buy a new clutch.

Controller has arrived its the KDH14801E Kelly. Need to make the liquid cooling plate next.


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## dtbaker (Jan 5, 2008)

if you have machining capability..... you might wanna pull off that starter gear ring while you're at it.


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## Jarrad (Oct 19, 2013)

dtbaker said:


> if you have machining capability..... you might wanna pull off that starter gear ring while you're at it.


If that gear ring weren't on there I could fit it in my lathe. I may do it at work next week although I was planning to have the motor installed by then.

Here's a shot of everything put together with the bell-housing plate, ready to align the holes. I like the way I can press the shaft into the motor end plate and assemble without the motor. Now I can locate the holes easily.


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## Duncan (Dec 8, 2008)

Hi
The starter ring will probably be a separate piece heat shrunk onto the flywheel - just cut it 95% of the way through with a hacksaw and hit it with a chisel

If you can try and machine a lot of metal off that flywheel - it is totally unnecessary on an electric motor and can give you problems with your motor shaft


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## Jarrad (Oct 19, 2013)

Duncan said:


> just cut it 95% of the way through with a hacksaw and hit it with a chisel


Alright sounds like fun!


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## Jarrad (Oct 19, 2013)

That's a big job for my little 10" Atlas.


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## Duncan (Dec 8, 2008)

Jarrad said:


> That's a big job for my little 10" Atlas.


It is a big job
But it is really important

The problem is called "whirl" - which is when the flywheel is off center and that initial off center cause a large force that drives it further off center

That puts a lot of load on your composite (several parts) motor drive-shaft and may start the new shaft moving in the old motor shaft

If possible you need to reduce your flywheel to the minimum necessary to support the clutch pressure plate

With the IC engine you need a flywheel to;
Even out the firing pulses at idle
Store rotary inertia so when you start off you don't simply stall the engine
Absorb the heat generated when the clutch was slipped to get started

None of these are required with an electric motor,
There is never a need to slip the clutch 

A lot of people simple eliminate the clutch and use a fixed drive from the motor to the gearbox


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## Jarrad (Oct 19, 2013)

Turning the flywheel is not too bad. The cast iron cuts fast.

I am thinking of getting rid of the clutch. I am only keeping it so I don't need to reverse my motor. 

I can now see it will not be difficult to separate the field and armature wiring and my controller supports reverse so I guess I'll figure out a direct shaft.


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## Duncan (Dec 8, 2008)

Jarrad said:


> Turning the flywheel is not too bad. The cast iron cuts fast.
> 
> I am thinking of getting rid of the clutch. I am only keeping it so I don't need to reverse my motor.
> 
> I can now see it will not be difficult to separate the field and armature wiring and my controller supports reverse so I guess I'll figure out a direct shaft.


I am running direct drive to the diff - so I lost the gearbox as well

With a FWD you probably can't lose the gearbox as easily, if you keep the gearbox but lose the clutch you won't need a reversing contactor as you will normally be changing from forwards to reverse when stationary

Without the inertia of an IC engine and flywheel you may be able to change gear acceptably fast even without a clutch - depends on your gearbox


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## Jarrad (Oct 19, 2013)

I think I will stick with the clutch until I see how it drives.

I have cut down the diameter to about a quarter inch from the screws. I faced the back down until I hit the screw holes. It measures a little over 5/8" thick. I can't think of anything else to cut off.


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## Jarrad (Oct 19, 2013)

If not using the clutch do you recommend a flex coupling?


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## Jarrad (Oct 19, 2013)

Here are some photos of the rest of the shaft work.

I pressed in the second shaft to mount my speed sensor on. I drilled the center taper out first so I can still mount the motor on centers after removing the shaft.


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## Jarrad (Oct 19, 2013)

Finally got the mini going but having issues with torque. I decided to bump this old thread so you know what my motor is. 

My problem seems to be the controller cutting out when I try to start from a stop. Unless I am very gentle on the throttle the car only lurches slightly then the controller faults out. If I am very gentle the car lurches a number of times then accelerates ok.

The controller is a Kelly KDHE. Fany has told me to return it but, I don't know if I want to waste the time or money returning to China. I tested the resistance on the terminals and the fets seem to be normal.

I don't think my batteries are the problem. I have logged around 100A output.

The throttle pedal is the original mini hall effect pedal wired correctly and producing 0-5v

The car drives ok once I get it started (a push helps) when I test it on blocks it seems to work great.

My last thought is there is a problem with the motor. One problem I had is that I had the brushed advanced the wrong way but I have fixed this and I am still seeing the same torque issue. I would expect to see high current and feel the motor trying but instead it just jolts and stops.

I just need to rule out the motor before I buy a Soliton Jr. If you can think of anything I could check I would appreciate it.


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## Duncan (Dec 8, 2008)

Have you tested the motor with an old car battery?

Car up on stands - see what happens?
I would expect it to spin - moderately fast

Can't think of a motor fault that would cause that

Try watching the battery voltage across the controller when you start
Is it possible it is going too low and the controller is shutting down?

Then check for any high resistance connector


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## Jarrad (Oct 19, 2013)

I have tested the motor with 12v a number of times. It turns freely and quietly with very little vibration even when in gear. My power steering motor is much louder.

I don't think I have any high resistance connections. .08" x .75" bus bars and 2/0 cable. My BMS doesn't show any problems.

I have checked for voltage drop. Here's a link to a chart of my logging. 

http://www.diyelectriccar.com/forums/attachment.php?attachmentid=27113&d=1410484701


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