The batteries are Lithium Ion (Li-ion) equipped with a critical discharge protection mechanism and have the following characteristics: ·Lithium Battery 3.7V 6000mAh. · They are kept charged for years, · You don't have to wait for them to be completely empty to recharge them · If you store them charged, you extend their life. · Although they are capable of withstanding 1000 recharge cycles after 200-300 charges, their capacity decreases gradually (they are still functional but with less operating time). Connect the charger to a suitable outlet and then connect the battery plug to the charger plug.