Why STM32 low power matters
STM32 microcontrollers can run from batteries for months or years when firmware uses low-power modes correctly. The real result depends on wake time, peripherals, clock speed and board leakage.
Run, sleep, stop and standby
Run mode uses the most current. Sleep saves some power. Stop and standby modes can reduce current dramatically, but wake-up time and peripheral availability change.
Firmware strategy
Wake up only when needed, process quickly, disable unused peripherals, reduce clock frequency and return to low-power mode as soon as possible.
Hardware strategy
Use low-leakage regulators, remove power LEDs, avoid pull-up losses and measure the full board current, not just the MCU current.