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Hello,
im using a Powerbank (Ansmann Model 1700-0134)+ WittyPi 4 + Rasperry Pi 4 combination.
When I use the button to start the board, everything works fine.
When I use a schedule script, the witty-pi doesn't start. With an external power supply everything is ok and the board wakes up as expected.
It seems like the powerbank goes into a sleep mode because not much current is drawn.
Therefore i used the <dummy load duration> configuration in the wittypi menu. I tried the value 10 and 1 but still the same problem.
The powerbank goes into sleep and after the Pi is shut down.
Do you have an idea how to solve the problem?
Best Regards
Posted : 09/06/2023 3:09 pm
Dummy load is a trick to keep power bank alive when Raspberry Pi is off.
Here is how it works: it draws rather big current from the power bank for a short duration and it does so with a fixed interval. That way the power bank might be fooled and think the load is heavy enough, and avoid entering sleep mode. However this trick is not always working and it depends on the implementation of power bank. Some power banks simply can't be fooled by such trick.
Possibile solution could be using a different power bank (ideally some power banks that has "always on" mode), or just give the power bank a real (and heavy enough) load. A real load can be a resistor or anything that can drop enough current from the power bank, and it can be connected to the 5V and GND pins in the unpopulated P2 header on Witty Pi. The resistor value should be decided by experiment, because it depends on your power bank.
Posted : 09/06/2023 4:34 pm