A 3D-printed holder for the 14500 battery (which doubles as a GoPro compatible ... The only other battery hardware needed are the contacts for an AA cell, but those are also easy to harvest ...

Listen up: We tested 15 AA batteries—the type typically used ... and repeating the cycle until the batteries die. Battery life was 7.3 hours for an Energizer, 6.8 hours for a Duracell, and ...