The I-Go comes as standard with a lithium battery stick installed in each side of the chair. Each battery stick provides 4 miles of range (tested on flat surfaces – while the I-GO can climb gradual slopes, it is not built for use in hilly areas or on rough terrain). Once one battery is depleted, simply pull the sticks out and swap them over to gain another 4 miles range, meaning on a fully charge of both sticks, you will be able to get approx. 8 miles of range from this power-chair. Please also note that the joystick charger will only charge the left lithium stick – once fully charged, you must swap them over to charge the other stick.