Pi Zero battery backpack case using a Samsung S5 Li-ion.

I think this offers one of the highest compactness to battery capacity ratios for a pi Zero, which is very ideal for a number of projects. You can get HATS for AAs or other LiPos, but nothing beats a good old widely available smartphone battery. Especially since it takes up little space around the Pi.

A 100mAH battery lasts about 20min running the pi Zero, so 2500mAH should last about 7.5 hours constant draw.

Samsung S5 Batteries are very reliable and pack 2500-3000mAH of charge. You can