Cellphones of the past came equipped with rechargeable nickel-based batteries with (Ni-Cd and NiMH). In the past few years, however, most rechargeable batteries used in phones are Lithium-based.

The smaller battery packs boast well over 40,000 reviews rating them a stellar 4.8/5 star rating. These rechargeable batteries use NIMH battery chemistry. The AA battery stores up to 2,000mAh and ...