Safety tip... dont charge your rotostart batt in the rotostart! There is probably a warning somewhere but I got it used without instructions.
I charged a old 1500 sport pack that was in my rotostart and when I pluged it back in and hit the button the damn thing blew up! Well it sounded like a shotgun... ears still hurt... and turned the rear batt cover into pieces
I guess the old pack must have given off some hydrogen or some other gas while it charged and filled the rotostart. When I hit the button the spark must have ignited it
So dont be stupid like I was!!!!!!!!!