The Electric Wrench is a tool added by Industrial Craft 2. It's the far sturdier, upgraded version of the Wrench, but requires recharging. On its own, it stores 12,000 EU. The amount of EU drained per use is determined by the mode of the Electric Wrench.
In the normal lossy mode, each use drains 500 EU and has a 20% chance of returning a Machine Block instead of the machine, much like a normal Wrench. Lossless mode can be toggled by right-clicking with the J key held down, and guarantees the retrieval of the machine. This, however, drains 10,000 EU per use, almost the entire internal charge of the device. The message Not enough energy for lossless wrench operation appears in the chat if the Electric Wrench does not have enough charge to function in Lossless mode. In addition, 50 EU is consumed every time the output face of a BatBox, MFE, MFSU or any transformer is changed.
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.