Raspberry Pi on a battery

two videos showing how long a Raspberry Pi runs on batteries, about 44 hours on 8 AA rechargeables for a model A+ and 14.5 hours in another test

https://www.youtube.com/watch?v=5Lw2bFTro58 8x GP2700 rechargeable AA batteries. It’s powering a Raspberry Pi model A+. In this test it lasted approximately 44 hrs 45 minutes.

https://www.youtube.com/watch?v=6Wj7bu3MkI8 14hr30min