eneloop NiMH "Low Self Discharge" batteries utilize Panasonic advanced rechargeable battery technology, allowing them to be recharged up to 2,100 times. This 4-pack of AA eneloop batteries deliver consistent power performance, maintain 70% of their charge for up to 5 years, come precharged by solar power (at the factory) and are ready to use out of the package. These 2,000 mAh eneloop cells also have increased storage life and extreme temperature performance down to -4°F.