This Wheelchair model uses two 12V 35Ah U1 (for 30 miles range) or 12V 55Ah 22NF (for 50 miles range) Sealed Lead acid batteries. These batteries are connected in series to make 24V system.
It can also take optional 12V 55Ah capacity to provide 50 miles range.
Range is based on a 180 pound driver on a flat surface. Range may vary depending upon the weight of the driver, state of charge of the batteries and the surface on which it is driven.
More information on Standard Battery
More information on Optional High Capacity battery.