Power Expander problems

We have been trying for the last couple of months to hook up a power expander so we could be able to run a second battery. But every time we have done this we are burning holes in motor controllers. This last time that we tried it caught on fire. We are thinking it is some kind of short, but haven’t been able to pin it down. Safety is now in full play. Do you have any ideas?

TCRC - Team Advisor

If you could post a picture of the burned MC that would be great. Have you tried other power expanders?, if you try another one and it works fine, you likly have a faulty power expander.

-How long have you used it?

Have you checked to make sure everything is plugged in right?