Apparently you can revive dead Ni-Cad batteries by zapping them with high voltage. Some people have used welders in the past, but many of us just don’t have access to one. This project shows you how to hack a disposable camera into a battery revival device. This could be very cost effective. A single regular AA battery could revive many Ni-Cads. Remember, this doesn’t charge them, just makes them able to be charged again.