Replace your current battery or get an additional battery to always have one ready charged. You can lock the battery to the frame with a key, and turn it on by the press of a button. The battery automatically turns off after you’ve parked the bike. Compatible: with Blix models sold in 2019 and later with serial numbers starting with "US": Vika+, Aveny, Sol, Packa (rear battery). Not Compatible: with Ultra, Dubbel, and Vika X models, or bikes with serial numbers starting with "CY". Battery capacity: 672Wh ( 48V/12.8ah) Expected range: Up to 45 miles per charge Battery cells: Lithium-Ion, 18650 Lifespan: 20,000 miles (400-700 charging cycles) Weight: 7 lbs Does not include charger .