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I am trying to use the Witty Pi 4 Mini powered from a power bank.
I have set the dummy load to the maximum dummy load duration, but the power bank still shuts off when the Pi goes to sleep.
From my tests it appears the Witty Pi dummy load is around a 50ma current pulse.
My power bank output stays on when at least 100ma is drawn from the output, so I need to increase the current pulse from the Witty Pi.
Is anyone able to tell me which resistor on the PCB is used to limit the dummy load current?
I want to try increasing the current by changing the resistor to a lower value so the power bank stays on.
Thanks!
Posted : 09/08/2023 11:59 am
Different than Witty Pi 3, there is no resistor on Witty Pi 4 to draw current as dummy load. Witty Pi 4 uses a different way and it momentorily powers Rasbperry Pi and lets it draw some current. Different model of Raspberry Pi will draw different amount of current, and model B draws more current than Zero.
If you want to increase the dummy load current with Witty Pi 4, you may connect a resistor between the +5V and GND in the GPIO header, or Vout and Catchode in the unpopulated header P3. However this resistor will become a real load even your Pi is on, and the energy consumed on it will be wasted.
Alternatively you may try connecting a big capacitor instead, which will increase the dummy current and has less energy waste.
Posted : 09/08/2023 6:09 pm