The methods used to calculate a power wheelchair’s battery level are different, so discrepancies between the app and joystick indicator lights may occur. The joystick display may consider a surface charge or fast increase in voltage when representing status on the battery indicator lights. MyPermobil calculates battery charge status using a Permobil exclusive battery calculation that takes into account a battery´s state of charge, state of health and the remaining driving distance. While no estimates can be completely accurate, as you learn how your wheelchair behaves in different conditions over time, the information presented on both the joystick and app will help you better gauge how far you can go each day.