The BatPack stores energy and is worn on the back. It is made from 6 RE Batteries, a Circuit, and a Tin ingot. It holds 60,000 EU. It's charged like a normal battery. You can charge it in a BatBox or other energy storage device, as well as any type of Generator, Another way of slowly but efficiently charging your BatPack, is wearing Static Boots or a Solar Helmet. It can be upgraded into a LapPack using Lapis Lazuli blocks and an Advanced Circuit.
You wear a BatPack like you would with a ChestPlate, Although it has NO armour value.
Equip the BatPack to your chest slot. If the tool you are holding is fully charged, the BatPack will discharge EU to the tool for each use. All of the first tier tools will take EU from a BatPack: