unofficial: Motors pseudo-overheating

VEX V5 Technical Support UNOFFICIAL Tech Support
1

In the official Tech Support channel, @flemigra001 wrote:

]Hi,
Our robot is having problems with motors appearing to “overheat” and stopping in the middle of our driver control period. The problem is that they are not warm at all; they just stop working. In some cases they twitch don’t generate any movement.

Details:
We are using 12 motors on our robot: 10 speed and 2 torque.
6 motors are used on our drive train, 4 on our lift and 2 on our claw.
We have our 2 claw motors (torque) y-cabled and run through a power expander; two sets of y-cabled drive train (4 speed motors) also running through the power expander battery. Everything else (lift and back two drive motors) is on the main cortex battery. Each side of our lift is also y-cabled (4 speed motors). This amounts to 5 y-cables total.

I have attached a picture of our motor port setup. We have tried to balance out the circuits on the cortex to avoid overburdening any portion of the board. If we are wrong on this please let us know!

Things We Have Tried:
Newer 7V batteries
New back-up battery
New cortex (in case our battery connections were worn or lose)
New motor controllers
Replacing the gears inside motors (to reduce any friction)
Slew rate code (for drive train motors)
Getting rid of Integrated Encoder Modules (We tried these for a day for some PID code and removed them the next day - robot randomly power cycled and had similar issues. Upon removing the IEMs we resolved these issues).

Nothing we have tried has helped. Robot works great when motors all function, but is completely crippled without all motors working. Our team is at a loss on how to fix this. We have state on Saturday and any help would be appreciated!

Thanks!

motor setup.PNGmotor setup.PNG

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2

It is because you are causing the ptc in the motor to trip and you have to wait tell the ptc resets.

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A couple of points:

  1. You get answers faster by posting in the unofficial areas.
  2. When people say their motors overheat, they do not mean they are hot to the touch. It means one of the PTCs (Positive Temperature Coefficient devices, which operate as a time-integrating current limiting fuse) shut down. The motors won’t be hot to the touch.
  3. You haven’t said which motors shut down.

Still, the answer is you’ve hit a current over time limit somewhere. More info=more help.

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You are probably using the motors to much or taking to much currect from the battery that the motors can’t handle it.

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@kypyro Actually that is not a problem, there are 2 PTCs inside the cortex Ports 2-5 and 6-9 ports 1 and 10 share the PTC. Because have you 5 splitters that are not evenly distributed you are doing 4amps or higher it is causing the PTC to trip. To fix this evenly distribute your power by having one splitter on each PTC then buy a power expander. This will relieve your PTC allowing them not consistently break. Tell me if this works for you or what actions you took to fix this. Also am I wrong anywhere?

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