Can a solar node using the RAK (wisblock) wake up automatically when, following the battery system powering it having gone flat due to lack of sun, the battery is eventually recharged when the sun shines again? There has been discussion about a wake up / restart needing a manual intervention like pressing a reset button or unplugging and re-plugging the (solar re-charged) battery. This issue is really important in case the node is placed somewhere inaccessible
(e.g. placed and left high on a building or pole to be āforgottenā). Does the node keep going for ever (when sun shines enough, baring other issues) or does one need access to it, after a power loss due to lack of sun, in order to perform a manual re-set action?
I found, with the following setup, by testing with a lamp and using attenuated light where the panel was struggling to charge the battery, that the RAK does restart, when the sun charges the battery system again, after being off due to lack of sun and the battery having run flat.
The light source was a 100W incandescent bulb, 10 cm from solar panel, with two 80 gsqm white paper covering the whole panel. Like this, it took 40 mins for the waveshare to charge and the RAK to start up after being off.
The setup uses a separate solar power management circuit from Waveshare and NOT the solar and battery connections built into the wisblock.
I did the test with a small (1100 mAh) protected battery i.e one that has itself an automatic low voltage off switch. This 14500 battery is in the Waveshare solar power management circuitās built-in holder. This battery choice was merely to test the circuit response and because that is the size of the battery case in the Waveshare version I was using. In practice one would want a much larger battery to keep the node going for many days when the sun is absent for many days.
(Many folks use for actual solar nodes at least 3500 mAh, which in my tests can run the RAK for about 5 days when there is no sun.)
The waveshare solar power management circuit has an input for a larger battery - one does not have to use a battery that fits into the holder on the circuit-board.
I will test with other, larger, protected batteries in future to see if this positive result indicating automatic restart of the node following brownout, works for those larger ones too (given the slightly different protection circuits that they might have).
I do not know if all this works just as well for unprotected batteries. I am told that the Waveshare D model (different to the one in this test) (see here https://www.waveshare.com SKU 26363 ), has the same effect due to a low battery voltage range cut-off and high voltage switch-on, which I presume works for unprotected batteries too, but I have not yet tested this.
Parts list:
In my test the Radio Configuration - Power - Power Config was set to OFF in the Meshtastic Android app.
Solar panel: Solar Panel (6V 5W) - glass - Opencircuit
Node: RAK Wisblock + Lora = SKU: 110082 und SKU: 115000
Waveshare Solar power management circuit: Solar Power Management Module, for 6V~24V Solar Panel - Opencircuit
containing the following PROTECTED Battery - Part number
12073 from https://www.akkuteile.de
The RAK was plugged into the Waveshare solar power management device by a USB cable.