How does an internal battery in a cartridge work?

Inside certain cartridges is a small coin-cell battery—usually a CR1616, CR2025 or CR2032—connected to a static RAM chip. This chip holds your save data, but it requires constant power to retain memory. The battery provides that power even when the cartridge is unplugged.

When the battery dies, the RAM loses power and your save data disappears. Replacing the battery restores power to the chip, allowing new saves to be stored—but any previous data is lost in the process.

Not all cartridges use batteries. Action games, fighters, and platformers often rely on password systems or don’t save at all. Battery-backed saves are most common in RPGs and simulation titles.