But AA Alkaline batteries last around 30-50 shots in a digital camera. You have to carry lots and lots of them to get through 7 days, at least the way I shoot. It’s much more economical and easier to pack if you buy 3 extra LiIon rechargeable batteries and start the trip with them fully charged. The OEM batteries are expensive, but the 3rd party batteries work fine and cost less than 1/4 the price.
You could go with low discharge NiMH rechargeable AA batteries; you’d need fewer sets of batteries than with Alkaline AAs but more than with a LiIon battery pack. It’s not a bad way to go, and my old Canon uses them, and if you have other electronics that use AA rechargeables it’s not a bad way to go. But you’re still buying a bunch of rechargeable batteries and you’re limiting you camera selection tremendously. There are much better cameras on the market that use LiIon battery packs than use AAs.