[quote name='Cthulhu8u']Ah OK, mine is a 6-7 hour charger that does 2 or 4, so obviously not a quick charger. TBH, my electronics usually need a pair of batteries, so I don't know how useful a single battery charger would be for me. 6-7 hours isn't the end of the world, so I'm cool with that.[/QUOTE]
It's more that the independent circuits charge each battery fully, but when they charge in pairs, each battery only gets charged until one is full. Since batteries discharge at different rates, this will leave one with less power than the other. It's just harder on the battery health, I think.