The Electric Treetap is a tool added by Industrial Craft 2. It's the far sturdier, upgraded version of the Treetap, but requires recharging. On its own, it stores 10,000 EU, and every use of the device drains 50 EU.
The Electric Treetap can be charged in a Generator, BatBox, MFE, MFSU, or any of the three tiers of Charging Bench. It can also be charged automatically by having a BatPack or LapPack equipped in the Torso slot of your inventory, or charged manually by having an RE-Battery in your inventory and right-clicking.