Major Voltage Drop using SMCs - Grasping at Straws

I have a strange situation and grasping at straws.

My basic question is there any way that two 18v15 SMCs can somehow cross connect to cause excessive current draw from my rover batter?.

Both SMCs are mounted on a metal plate with metal standoffs. I am assuming the holes for the standoffs are not grounded - they appear not to be. I am pretty sure the standoffs are not touching other traces.

It will be a big hassle to insulate the SMCs but if necessary I can.

I cannot detect a path between the two but is it possible?

The SMCs are driving a Wild Thumper. When going forward or reverse everything is okay. When trying to spin the voltage measurements on the SMCs drops from 7.4v down into the range of 5.8v. The batteries are 10Ah 25C LiPo (at times 2 in parallel and the same happens.)

I just measured the entire chain from battery to motor with no SMC in the circuit. At 13 amps with two motors stalled the battery drops 0.5v so it is not just the motors stalling that is causing the voltage drop. There are normally 10 amp fuses on each motor controller. Since they do not blow the current is not greater than 10 amps for very long, if at all.


If you lift the chassis off the ground and command it to spin, does this same voltage drop happen? If so, could you disconnect the motors entirely from the two simple motor controllers and repeat the test, and see if that same voltage drop happens?

- Zeeshan