aluminum to steel electrical corrosion

[Doug1]

I need an electrical guru to help me understand the chemical reaction happening here. This aluminum bracket has corroded in less than a week and with the power cut most of the time using the remote battery shutoff solenoid that is mounted to this very bracket. The other solenoid is a high amp alternator shutdown. Both made by Painless Performance.

I did have to put a 300 amp charger/starter on it for a little while last week when I was working out the ignition issues but I don't know if that affected this in any way. Regardless, I need to get it figured out sooner than later! I'm going to isolate the aluminum from the steel below but am not sure that would cause this much corrosion in such a short period of time.












I need an electrical expert to chime in on this!