A recent test with fresh AAA batteries and the micro:bit displaying a single LED always on lasted 6.5 days.
If you want to know how much power you have left you can measure the battery capacity and get a reading on the LED screen
If you use the battery pack with the micro:bit and want to prolong battery life further there are some tips you can follow:
- Disconnect the battery pack after use and if you are not going to use it again for a while, remove the batteries.
- The radio function once on is always listening for signals, so this can drain the battery. Disconnect the battery pack when you are not using it, or if you are programming using MicroPython you can use radio.off() in your program.
- If you are using the LEDs, consider saving energy by setting them to a lower brightness level. In MakeCode you can use the set Brightness block which takes an integer of 0-255 and in MicroPython, you can use display.set_pixel() which takes the column and row value of the LED you want to change the brightness of and then an integer of 0-9 eg display.set_pixel(0, 2, 5)
- If you are driving third party accessories or peripherals such as LEDs, these will also contribute to battery drain, so you may wish to use a separate power supply to drive these.
If you have any more tips, get in touch