Car key batteries (also called key fob batteries) are small, non-rechargeable lithium coin-cell batteries that power the remote transmitters in modern car key fobs. They enable functions like locking/unlocking doors, opening the trunk, and (in smart/passive-entry systems) keyless start.
Chemistry: Lithium / manganese dioxide (Li-MnO2)
Voltage: 3.0 V
Size: 24.5 mm diameter × 5.0 mm thick
Typical capacity: ~540–620 mAh
Shelf life: Up to 10 years (very low self-discharge)
Not rechargeable
Common vehicle uses include:
Certain BMW smart keys
Many Ford models (F-150, Ranger, Explorer, etc.)
Jeep, Dodge/Ram, Volvo, GMC, Chevrolet, and others