Very little to none - accelerometer packages also handle some power management themselves, typically with various 'modes' of accuracy and sleep/awake states. Th

Very little to none - accelerometer packages also handle some power management themselves, typically with various 'modes' of accuracy and sleep/awake states. There are a number of embedded devices (my FitBit, for example) based around MEMs accelerometers and tiny batteries with a charge that lasts days, if not weeks. Compared to everything else that's going on (backlight, CPU, WiFi or the cellular modem) it's peanuts.