Stalling the BaneBot 775 motors

[AdamHeard]

Originally Posted by dtengineering

Try strapping a cooling fan to the motor. A few zap ties and one of the little fans might make a big difference... you could even try making a little duct work to blow it all in one end of the motor... but that is probably overkill.

Our nerf ball shooter in Aim High was an FP that ran about 5-10 amps. It would be on for a fair bit, but not all, of the time during a match, it would be turning... and it would be... not hot, but definitely warm, by the end of a match.

I would suggest that you try running the motor at your predicted loads on a test bench in the shop before you even mount it on the robot. Just lock the shaft and run the motor at your expected current. Actually, since this is a test... start at half your expected current. Hold it there for two minutes. It would help if you had an IR thermometer to track case temperature, but remember that the real heat will be forming in the coils and will take a while to get out to the case. This will be fairly simple to do if you have a clamp-on ammeter, but if you don't, I believe the Jag can be convinced to give you feedback on your current consumption... you may even be able to just send a "give me 5 amps" command to the Jag. The real heating situtation during a match will be quite different, of course... the motor will draw a lot of power as you lift the arm, and then, perhaps before that heat has a chance to be "blown away" by the motor's fan, you'll be stalled... so it may not be just the stall heat that you have to deal with. Of course, then you'll lower the arm and the motor may have a chance to rest and cool, but perhaps you can run it through a few cycles like that over a two minute stretch.

Then keep in mind that you may or may not have time to cool your motor between matches, particularly during practice matches. We've been fortunate to clear tech fairly quickly from time to time and get practice match after practice match after practice match. One year we had to pull out from the practice field because the drive CIMs were starting to overheat! Just think what would have happened to one of the little motors!

Jason

P.S. Another time your motors will be subjected to extended heating and use will be in the post-season while doing demos.

You could do this test by locking the shaft to force stall, and setting the voltage to the proper value. To get 10% of stall, set 10% of 12V.