The Bill and Melinda Gates Foundation has funded research to develop a pee powered smartphone battery... but you can make one right now. The Bill and Melinda Gates Foundation has funded research to develop a pee powered smartphone battery... but you can make one right now. Lemon batteries are cool, but salt batteries are powerful. And, hey, there's salt in urine, so a urine powered battery would be the ultimate emergency battery to top off you cell phone, right? Sure, if you're squeamish, you can use salt water instead o' urine! We show you how to build a battery from aluminum foil, copper wire, charcoal, and salty liquid that'll charge a smart phone in the video!