I've owned a long-time conversion for the last 7 years or so. It is a
medium performance conversion with ThunderSky cells (still going!), Kelly
KDHD Series Controller and ADC FB1-4001-A series DC motor. You can see its
history at: www.evalbum.com/2778
I'm having a performance problem with the car at low speeds, and trying to
figure out whether it's the motor or the controller. The symptoms are:
- Very sluggish acceleration at low motor speeds.
- Almost no voltage droop from the batteries while having the sluggish
acceleration (Low battery amps, as expected).
- Better acceleration at motor speeds above 3000 rpm.
- Good battery amps (60-70A) when driving at highway speeds. Normal
performance when operating at battery voltage.
If I can get to highway speeds, the car does fine, but starting out in 1st
gear to get started is excruciating. I think my 0-60 time is probably 50-60
seconds. Without a clutch, it takes about 5 seconds between shifts for the
motor to spin down the 1000 rpm to match the transmission. A little less if
I abuse the synchros.
>From this, I'm sure that my amps, at low voltage, when the motor is turning
slowly, are limited for some reason. I'm not sure if the controller isn't
providing the amps, or the motor isn't drawing them. The controller is
supposedly rated for 1000A, but it's never done that. However, it always
had enough before to accelerate a little better than the original gas car.
I did check the brushes and they were in sad shape. The ADC motor has 4
pairs of brushes, on two windings. On one winding, the left side on both
brushes was mostly shot. On one brush, the copper braids were completely
gone. On the second brush, the copper braids were nearly gone, just a few
strands of copper left.
The brushes have been replaced, shaped and run-in for about 20 hours now.
I'm running the motor at about 1500 rpm with no load (transmission connected
but out of gear).
Performance is a little better, but still not right. I still have another
- Is it possible that the brushes aren't full seated yet? Could that
cause this kind of problem?
- What can I do to put an artificial load on the controller to see how
many motor amps it's providing?
- I don't have instrumentation on the motor amps right now. Is there an
easy way to do that?
- Is there an easy way to provide power to the motor while under load and
the car is moving? I would have to go to a shop to have the motor pulled to
test it outside the car.
- Any other motor checks I should do?
Any other thoughts anyone has? Any suggestions on the tests above to
isolate the problem?
Thanks in advance for any help.
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