Currently running 12 motors. 4 on omni X dirve, 2 for claw and 6 for lift. Claw is internally geared high torque, all six on lift are internally geared high torque and four on drive train internally geared high speed and shafts directly into wheels.
Rear two drive motors (rear of bot is heaviest due to being under lift) and two of the six lift motors are plugged into power expander. Two motors of claw are plugged into port 1 and 10 on cortex and the other two drive motors, front of machine along with other four lift motors are plugged into cortex. The four lift motors are split with two in port 2 and 3 and the other two in ports 8 and 9. Thinking this is split well to distribute power, we still experience some drive train motor failing.
This may not be a wiring problem. Sounds like it could be motors overheating and tripping the internal PTC due to excessive stress. How heavy is the robot? Is it large and made out of steel?
Assuming the ptc circuits are not failing, the best thing to do is to wire in a way to recover form a ptc trip.
For example, our old configuration was off only the cortex:
1: Wheel 1(Front right)
2: Y cable for 2 motors on one tower
3: Wheel 3 (Front Left)
4: Motor on opposite tower
5:Claw one
6:Claw two
7:Motor on opposite tower
8: Wheel 4(Front Right)
9: Y cable for 2 motors on one tower
10: Wheel 2(Back Right)
I’ll have weight on Wednesday… mostly Aluminum though. Could be motors over heating. May have to go to high torque internal gearing on drive motors. Photo attached.
Looks good except I think port 8 should be Back Left. Port 1 is Front Right.
yep. messed that up 
What about running power expander?
An X drive travels 1.4 times as fast as a tank drive. So, if you are using 4 inch wheels, your effective drive ratio is 1.6 (speed gears) x 1.4 (x-drive) = 2.24. This is too fast for your robot.
Going to torque gears will give you 1.0 x 1.4 = 1.4 effective ratio which will help make your drive operate more reliably.
I believe a power expander will help prevent your cortex breakers from tripping, but it will not help with stopping your individual motor PTCs from tripping if you are overworking the motors.
We are using the smaller omni’s.
Ok, so 3.25 inch wheels changes your drive ratio from 2.24 x 3.25 (smaller omni) /4.0 (standard omni) = 1.82 current ratio.
We have changed our 4 motor tank drive ratio from 1.6 to 1.3 because we could not push or drag objects at all without burning motors. The 1.6 drive ratio contributed to us burning the drive during back-to-back elimination matches, hence the change.
If you change to torque motor gearing, your effective ratio will be 1.14. This will be very reliable but perhaps too slow for your liking? Some teams really prefer to ensure the reliability, but 4 inch wheels with torque gearing may give you a better balance between reliability and speed.
Really your final gear ratio depends on whether you want to be able to push objects or not. Your current 1:1.82 gear ratio should work for anything under 14ish pounds, but not reliably and you won’t be able to push anything. In the picture I see some (not very much) extra c-channel that should be removed. Try a weight loss program for your robot; anything extra that you don’t need should be cut. One piece of cross bracing across your robot is enough; if you feel it’s necessary avoid 5x c-channel. Triangulation pieces could be shorter abd provide pretty much the same amount of strength; the 5x c-channel that connects your claw to the arm could be shorter too. Remove those plates of lexan and replace it with rubber bands. Little things add up. Just be sure not to remove anything that’s actually necessary.
Weight came in at 15.5 lbs.
we changed the internal gearing from high speed to high torque. This seems to have solved our motors cutting out and the speed really isn’t that bad.
The slower speed will aid in our effort to hang during the 15 sec autonomous period and since we are really only navigating 1/2 of the speed looks ok.
Driving skill will also help to keep unnecessary load off the motors.
Thanks for all the assistance.