Just so you know.......if you want to corrode a metal, here's the way to do it.
Put an untreated aluminium sheet next to a half sniffed at steel box section ( raw inside ), and finish off the circuit ( assuming it's a -/+ve earth system ) with an untreated iron fastener joining the two metals. Not just placed between them but threaded and screwed as a joint in order to properly open up the surfaces of the relevant metals to promote their conductivity. And then add water ( salty for us) and electricity.
I'm surprised Defenders don't charge their own batteries overnight........they should at least contribute to the Grid.