Panasonics 21.6V Li-ion cobalt battery pack
 The 21.6V 3.0ah Cobalt Li-ion battery pack delivers high output with low heat generation resulting in twice the lifetime total performance versus current Ni-Cd battery packs. The GuardION system monitors EACH battery cell during battery charging and during tool use to prevent over discharging and overheating of the battery pack thus insuring long life.