In the Chicago crash, IIRC, the battery lasted 6 minutes. You could carry one battery in your hand they were that small.
I believe a RATT did indeed fall off a Scampton Vulcan
We once had a spectacular RATT malfunction. We were doing 350kts across the Libyan desert and there was a loud bang. The RATT did what it was supposed to do and slammed a lot of wiggly amps onto the bus before burning out. I think it also blew a few other circumstances circuits too.
Back at Akrotiri the crew chief 'fixed' the problem and we planned another sortie, fully fuelled, with the plan of dropping the RATT at TOC before commencing the sortie. Why j have no idea. RATT dropped and failed. 5 hrs fuel to burn off and t2t he chief apologised for not checking the fuses.