For the price of a mid-range Android phone, [Kenneth Finnegan] turned a 50 caliber ammo can into a 50 amp-hour portable power supply. The battery pack uses four 3.5 V LiFePO 4 cells wired in ...

The .50 cal ammo box wasn’t in the greatest condition when he picked it up, so he completely sanded it, re-painted it, and lubricated the rubber seal. Inside, he loaded it with four 7.1Ah sealed ...