Cockney Steve
the batteries in service(and changed) have been abused!
This was my feeling as well - perhaps not deliberate abuse but slavishly following the laid down procedures which perhaps have some instructions that 'assume' that nobody-would-do-that. Or perhaps procedures that
assume that the aircraft will be in a particular state when something is done (e.g.
all electrics powered down for a battery change.) but don't actually require it.
What abuse do you think could cause a single cell to be on the edge so recharge or even use while parked would cause a problem?