Robot cutting in/out

We are experiencing a problem with our robot that while driving it around it will occasionally cut out so that we can still hear motors trying to drive but are very weak…then we stop moving for 10 seconds and everything with be working again fine.

This first question is so ridiculous I almost feel like I’m trolling, but it pays to ask the simple questions anyway.

  1. Have you tried different batteries? / Are the batteries fully charged? / Are the batteries plugged in properly?

  2. Does this happen consistently or only in some scenarios?

  3. Can you give us any information on what you have tried so far to remedy the situation?

picking up the robot and driving the wheels
does it still happen?
if not, gear your drive down

It sounds a lot like your PTC things are getting too hot.
This caused by drawing too much current from the motors, which is when the motors are getting full power but are not turning very quickly.
It typically takes about 5 seconds for ours to reset.
The PTC thing will increase the electrical resistance drastically when the motor gets too hot, so the motors will still run, just very slowly (as you have described).

What is the configuration of your drive wheels? How many motors are you using? What is the gear ratio? What size wheels are you using?

To fix this problem, simply gear your drive down (for torque) as murdomeek suggested.

The last common cause of this is excessive friction in the drive train. If you gearing is correct and your batteries are charged, make sure your wheels spin freely when the motor is disconnected.