Panasonic Eneloop BK4MCCA12FA Ni-Mh Pre-Charged Rechargeable AAA Batteries - 12 Packeneloop NiMH Low Self Discharge batteries utilize Panasonic advanced rechargeable battery technology, allowing them to be recharged up to 2,100 times. eneloop batteries deliver consistent power performance, maintain 70% of their charge for up to 10 years, come pre charged by solar power (at the factory) and are ready to use out of the package. They also have extreme temperature performance down to 4 deg F.