I have a tiny Sony DSC-W570 camera. It has a 600mah battery, which does not last long (maybe, enough for 100 pictures or so, depending on outside temps and whether flash is used each time). I have a spare battery as well, but what if I need it to last for the whole day, or even multiple days without a need for an AC socket?
Is there some kind of AC charger on-the-go with built-in battery for 6000-9000mah, which stays in a backpack (for example), where I can stick my smaller battery (through a regular wall charger) and charge it while the backup battery is working? Once drained, switch them, and keep taking pictures.
This way I could increase battery life 10 times. Especially useful for occasions when AC plug is not expected to be available soon (i.e. hiking and similar).
I googled hard before asking this question, and all I found was such chargers with USB connectors, so they are only useful for charging phones (iPhone, Android and the like).