could it be a defective mmm?

[Thomas Porfert]

I've seen this before on some Monster setups when wired in series; maybe 3 or 4 times. It makes absolutely no sense because as far as the controller is concerned, you are running one battery. It doesn't have the ability to drain power from one battery and not the other.

The craziest part is when you switch position on the series harness, the problem doesn't follow the battery, it stays on the same connection on the series (it was always on the positive side); I'm assuming that's what's happening here. Honestly I could never figure out the issue, even different sets of batteries didn't fix the problem. My only solution was to send it in for repair.

I wish I had a better answer, but this is one of those "ghost in the machine" kind of things that can make you pull your hair out; and when logic fails in troubleshooting, abandon all hope...and send in the cursed part for repair.

Thomas Porfert
Castle Tech Support