8.4v 1600mah Tenergy Mini Battery (NiMH)
Constructed of Nickel Metal Hydride, this battery is a great purchase for the beginner or intermediate airsoft player. The chemistry of its construction make it low maintenance and cheap on the pocket. The capacity of this battery is 1600 mah, which translates into about 1600 shots before it needs to be recharged. This battery can typically go through 300 charging cycles before losing efficiency and eventually becoming useless for airsoft skirmishing. Also it only requires discharging for the first 8 cycles of use, after that it can be topped off as needed. Remember to recycle this battery instead of throwing it in the trash!

Note: If your battery is not recognized when attached to a "smart" charger, it has probably entered a super-drained state. Simply attach it to a "dumb" trickle charger for 30 minutes or so and this should fix the problem.