Blown CIM?

[FrankJ]

Originally Posted by Ether

Easier said than done, if you don't have a dynamometer.

Perhaps consistent or the same would have been better then "known". I was trying to think of simple tests without a lot of instrumentation.

I agree that ohming the motor has limited usefulness. It will tell you if you have open windings or a really bad commutator. Shorted winding look about the same as good windings to a typical ohm meter. Once again things to do with minimal tools.

[evand4567]

Did some testing and they definitely are degraded. Thanks for the help.

[Ether]

Originally Posted by evand4567

Did some testing and they definitely are degraded. Thanks for the help.

Now you can return the favor.

Please post your test procedure and test results so others may learn from what you did.

[evand4567]

We tested the resistance with an ohmmeter and found the degraded ones to be between .3 and .5, while the new CIM varied between 5-15 depending on it's position which is strange and I don't really understand what was going on.

Now for the unscientific part: we direct drove a wheel on and found a significant reduction in RPM noticeable to the naked eye. The sound motor sounded significantly slower as well.

That was enough for us to conclude the CIMs were bad, but if there's enough interest and I have the time, I can do some more specific and scientific testing of the motors.

[Ether]

Originally Posted by evand4567

We tested the resistance with an ohmmeter and found the degraded ones to be between .3 and .5

.3 and .5 what? ohms? milliohms?

while the new CIM varied between 5-15

5-15 what?

Now for the unscientific part: we direct drove a wheel on and found a significant reduction in RPM noticeable to the naked eye. The sound motor sounded significantly slower as well.

That's arguably more scientific than measuring resistance.

[Ether]

Originally Posted by evand4567

We tested the resistance with an ohmmeter and found the degraded ones to be between .3 and .5, while the new CIM varied between 5-15 depending on it's position which is strange and I don't really understand what was going on.

Can you please tell us what the .3, .5, and 5-15 numbers are?