12volt battery for camera

Hi there, I am wondering if someone can help me with a project I am working on. I have a digital camera (Canon A570 IS) which is powered by two AA batteries. I have installed a firmware update to the camera which allows for custom time lapse shots. I want to use this camera in a remote location to take a time lapse over a long period, at least a few months. The location I am going to put it does not have electrical outputs available. I am thinking that if it is possible I would like to connect a car battery to it to extend it's life. Is this possible? How? Thanks,

The best is to get a BIG 3V battery. Maybe search, else others know....? But sticking to common hardware solutions..... have you tried Energiser Lithium? (Apologies for the plug, but these are well worth it for cameras and I'm a stinge with money - and hate overrated (actually often well over-rated) expensive batteries!) Or maybe (the same) in D-size since you have to somehow connect the power anyhow, and that avoids complications. Otherwise perhaps an AGM battery with a phone charger or similar, though the loading of the charger has to be considered. Else a linear regulator set to 3V <whatever> - eg, a LM317 chip with 2 resistors. The linear (LM317) may be more efficient than a phone charger, and could be used of a 6V battery IF they are cheaper. With apologies to haemphyst for mentioning this again, but I quite liked the Yuasa NP12-7 (12V-7AH) battery which is about AUD$35. (It was more that price that amazed me - same price as the 4AH, and cheaper than inferior equivalents.) But being a common battery, any 12V-7AH battery is probably the best bang for bucks in a small battery. I'd expect the phone charger to be more efficient than a linear regulator in that case - whereas a linear regulator pulls the load current from the battery, a phone charger uses SMPS so from 12V to 3V means down to 1/4 the 3V load current being used from the battery (ie, Watts in = Watts out excluding inefficiencies). BTW - I'm taking about SMPS = dc-dc converter type charges as sold for 12V-24V cig sockets for iPods, phones, GPS etc. But I'd probably disconnect the charger's LED - assuming the charger needs no minimum load to regulate its output (and they usually don't) - to give longer battery life. In summary, with a big 3V battery, the only load is the camera. With other voltages, the regulator/converter adds to the load. Both cases required calculations to determine expected life. Or a trial run - a D-cell should have about 4-7 times the capacity of an AA cell.    FYI - Lately I've been snapping up old chargers being sold for $2 each. That's partly for their >$5 fused cig plug, but more for their $5 MC34063 dc-dc converter chip, else to reconfigure for 5V or other desired output voltages. If you decide to go the voltage conversion path, we can discuss options later.