I have a project that pulses a Western Union slave clock every hour to snap the minute hand to 12. My battery powering the BIT isn’t lasting as long as I hoped. I found the POWER extension for the V2. The idea is that right after I pulse the correction solenoid I go into low power mode for 59 minutes. In a test project, the BIT, with nothing except empty Start & Forever blocks, draws about 15mA. If I add a Request Low Power for 10 seconds block, it only drops to 14mA. There is something in the extension documentation about going into Low Power mode only when the BIT is idle. I tried Pause blocks before and/or after the Request, but it made no difference. Maybe I’m missing how to force idleness (no pun intended). TIA Don
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With this project, fresh AAAs and a multimeter, I measured:(mA):4.2 - 4.4 on start, 12.9 - 13 after pressing A, 2.2 - 2.5 after pressing B.
I tried it with MakeCode v4 (https://makecode.microbit.org/v4) and measured: 4, 12.6, and 2 - 2.2
What is the normal draw of your actual, non-empty project? And during low power? Can you share the code? What battery?
Low power happens when everything is idle, potentially at the end of a forever loop (there’s an included pause) or during any other “blocking” call, such as show icon, that would allow a switch to a different loop or handler, but only if there isn’t another loop or handler that wants to run.
When a program wants to wake up and do something, it may need to wrap the code with low power prevent and allow blocks.
Low power is blocked if Bluetooth is connected, and possibly (i.e. I’m not sure) if there is ongoing serial communication.
Those look about like about the ma I saw a month ago, disappointingly. I was hoping for sub-mA draw when sleeping. I’m using an 18650 9900 MaHr LiION rechargeable battery. My app simulates a master clock that resets a Western Union slave clock every hour. I sleep for 58 minutes then show countdown on an OLED display then pulse the solenoid for 200ms to snap the minute hand to12. I could only get a couple weeks out of it. Now gone to a USB plug-in for power. With a 50 lb clock, this needn’t be exactly portable. Of course this wouldn’t be the first battery from Amazon that didn’t actually supply the claimed capacity.
Don Central VA
With 18650 battery, or USB power supply in a custom circuit, there is a risk of damaging the micro:bit, clock, battery, or power supply, and of causing a fire.
Please see the power supply information, and the safety guidance.
Two weeks seems low, even for the currents you measured. Maybe from converting battery voltage to 3V?