Batteries have their own input and output speed limits depending on their size; Small Batteries can absorb or release power at 1U/s, which for reference is approximately one bar on a Small Battery every four seconds. Medium Batteries behave like five Small Batteries, at 5U/s, and store and release energy five times as quickly.
The Backpack Battery is a built-in battery which allows the player to use various items on the backpack, as well as utilize the Backpack Printer. When tethered to a base, the backpack battery takes priority over other items until it is fully charged.
Small Batteries are Small items that can plug into any slot. They store up to 32 Units of power.