Batteries add charges to Isaac's active item when picked up.
Battery
ID
Image
Charges
Notes
Unlock Method
Lil' Battery
5.90.1
Full 6
If Isaac has The Battery with no overcharge, only the main charge bar is filled. If the main bar is full, the overcharge is filled.
Micro Battery
5.90.2
2
Mega Battery
5.90.3
Full (x2)
Overcharges Isaac's active item up to two full charges as if The Battery was held. If Isaac has multiple active items, it will charge all of them twice.
Golden Battery
5.90.4
6
Deals a full heart of damage when picked up. Another golden battery will spawn in a random room, but it is not shown on the map until discovered.
If a Golden Battery appears in the Abandoned Area before the Mother's Shadow chase, it will despawn for the floor, as the room configuration is changed when the chase begins.