[nuttle]

I'd also very carefully check the condition of the contacts. Could you have a charger cable that is scratched up and damaging the battery connectors? This could be the type of thing you'd only see upon close inspection. Also, anyone happen to know how many mate/unmate cycles are specified before contact resistance becomes too high? For example, plating wears away, metal oxidizes, and you now have much more resistance? Or, maybe the spring loses enough force that the contact is no longer very good?

Also, can't count the number of times I've seen someone use the leads as a carry handle, but that's another topic.