From Sega Retro

CR2032 battery

CR2032 is a designation for a small 3-volt battery about the size of a nickel, very commonly used as the battery for supplying power to SRAM chips to prevent them from losing the stored information when the console is turned off.

  • Standard Discharge Current: 0.2 mA, 0.03 mA (BR)
  • Maximum discharge current: 3 mA
  • Maximum pulse discharge current: 15 mA

It's a very popular battery and in case you ever need to replace an ailing CR2032 they're sold at most electronics stores.

Uses of the CR2032