2012 motors?

[PAR_WIG1350]

Originally Posted by JesseK

CIMs can get closer to stall conditions multiple times before burning out. We've had BB550's & 775's smoke after a few iterations of running them around 30-35 amps for prototype lifts. I'm a bit smarter now than I was then so I can calculate for some safety margins, but for a drive train I don't think there's enough safety margin for these motors.

I think, iirc, 25 tried 2 BB550's + 2 CIMs in '08, and said they had to replace the 550's a couple of times. I think they wound up going down to 2 CIMs only in Atlanta? I could be mistaken.

Of course, I could totally be missing something; I wasn't around for the drill motors of '04 so I don't know how many of those burned out on field.

Smaller motors , by nature, have issues dissipating heat. CIMS, due to their large size, can be run closer to stall because they can dissipate the associated heat.

A non-defective 775 should be better at running at or near stall for limited periods of time, unlike the 500 series, since, once again, its larger size can dissipate the heat that results from inefficient operation, but if there is an internal short, the resistance is less than it would normally be and the current can exceed the rated stall current producing more heat faster than the motor can dissipate it which eventually breaks down the enamel insulation on the wires and causes more shorts which causes more heating and, if it allowed to continue, the motor could potentially catch on fire.

500 series motors are much more susceptible to overheating. Their small size prevents them from dissipating much heat at all passively. Instead, they rely on internal fans to actively cool the armature. 500 series motors, as a result, will overheat if they even get close to stalling. It is best to allow 500 series motors run fast and gear them to the desired speed.