Seems like you can get AA power pack that has a USB output, and use that to power/charge a standard smartphone (maybe one with a removable battery, if you want

Seems like you can get AA power pack that has a USB output, and use that to power/charge a standard smartphone (maybe one with a removable battery, if you want to be a purist about it)? https://www.coolerguys.com/products/usb-aa-battery-charger-and-portable-power-supply-1 https://www.coolerguys.com/products/usb-aa-battery-charger-a... You can do some rough back-of-the-envelope math for this. A typical smartphone might last about a day with a battery about 4500 mAh @ 3.7V nominal = about 16 Wh. That battery pack of 4 AAs is about 48 Wh, so it should run the phone for 3 days or so (with some losses). But depending on the phone, it may or may not be able to run off a standard USB outlet anymore (USB-A is usually limited to around 10W, some newer phones need ~18W to properly charge while on). But anyway that should give you an idea. With batteries and some electronics, you should be able to make a modern smartphone run off AAs. Here's a youtuber showing something like that: https://www.youtube.com/watch?v=-qObYrj1Foc&t=633s https://www.youtube.com/watch?v=-qObYrj1Foc&t=633s (or a DIY version: https://www.youtube.com/watch?v=TaoCPv0GTSg https://www.youtube.com/watch?v=TaoCPv0GTSg) The question then is if you consider a "phone" a "computer". If not, probably you can find some Raspberry Pis, Beaglebones, etc. with a similarly low power draw. Or an Apple Watch, for that matter. From there it's just an issue of having enough AA batteries in series and some voltage converting electronics/USB ports to connect them to the smartphone. There is nothing inherently impossible about this. Low-power electronics exist (in everything) these days. We just don't use AA batteries because li-ion is more energy dense (capacity per volume) than most AA chemistries, and if you're going to use li-ion anyway, a flat form factor is typically easier to carry around in a pocket than cylindrical cells.