Ni-MH rechargeable batteries. Furthermore, they supply energy for longer than traditional Ni-MH batteries. Traditional Ni-MH batteries fail to work once the voltage drops below 1.1 volts, whereas Eneloop batteries keep the voltage level over 1.1 volts for a longer time. For photographers who use very high drain equipment, Eneloop can therefore be the difference between missing and capturing that perfect shot. Free battery case.