RE Battery

The RE-Battery is a tier 1 portable energy storage device capable of storing and transporting up to 10,000 EU. It's recipe consists of 4 tin ingots, 2 redstone dust, and 1 insulated copper wire. It is one of the first steps getting started with industrialcraft. It can be charged in a BatBox, and MFE, or an MFSU.

They are cheap and can be crafted very early on in the game, which makes them very useful in a new world.