Blown CIM?

[GeeTwo]

Originally Posted by FrankJ

Another possibility would be to run it with a known load & compare its speed & current draw against a new motor.

Originally Posted by Ether

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

You can compare a questionable motor to a known good motor by using the same load for each test. You don't necessarily have to know what the numerical value of the load is.

For example, if you have a CIM-powered elevator lift you can measure the lift time for a good motor and a suspect motor (using the exact same throttle command each time), and compare the results.

If you have a CIM-powered lift lying around (and for some strange reason a lot of teams do right now), you can use it to "measure" the stall torque by finding the weight of a load that you can just barely lift. You can also use it to evaluate performance near the maximum power by lifting approximately half of the stall weight and clocking the lift time. I fully concur with Ether that the simpler tests would be to compare your suspect CIM(s) to a population of known good ones, rather than trying to work through all of the gear ratios and possible sources of friction.

Also measure free speed and curent, as Ether put in post #1. Unfortunately, I don't think you can get a good stall curent measurement with the PDB as a CIM has a typical stall current of 133A, and IIRC, the current meter saturates at about half of that. Even if the limit is high enough, be sure to use a motor controller, as powering a motor directly from the PDP can damage the current sensors. Especially when you do the stall measurements, try to use the same battery in the same state of charge and the same wires for all the CIMs you test.