the joystick to query.
a pointer filled in with the percentage of battery life left, between 0 and 100, or NULL to ignore. This will be filled in with -1 we can't determine a value or there is no battery.
the current battery state or SDL_POWERSTATE_ERROR on failure; call SDL_GetError() for more information.
Get the battery state of a joystick.
You should never take a battery status as absolute truth. Batteries (especially failing batteries) are delicate hardware, and the values reported here are best estimates based on what that hardware reports. It's not uncommon for older batteries to lose stored power much faster than it reports, or completely drain when reporting it has 20 percent left, etc.