We have several Link.One devices which include the RAK19007 WisBlock Base Board 2nd Gen and the MPU has been completely wiped (no bootloader or anything)
Our setup includes solar power connection (5v) and a switch on the battery to allow for long term storage.
We are seeing that when the battery switch is turned off and the solar connection is connected, the red charging LED is blinking - this is normal according to the TP4054 charger datasheet.
However, we experience a problem where the MPU does not execute its program when battery is switched off. When the battery switch is cycled, the RAK4631 is completely wiped and cant even load the bootloader.
Is there a possibility that when the battery is switched off, the charge chip is providing an undercurrent to the dc-dc converter which causes the MPU fail?
The RAK4631 depends on two separate power supply inputs, 3.3V from the DCDC converter and directly VBat from the battery.
I have boards where I disconnect the battery complete and the switch is located between the battery connector on the RAK19007 and the battery itself. So both supply voltages are switched off and I have not seen any problems so far.
I did not do any tests with switch and solar panel, but the supply input setup should not cause any problems and you can supply the device through a solar panel only.
However, a solar panel cannot provide a stable voltage and supply current. The variations of input voltage and current could cause a problem.
I would not recommend to supply a device only through the solar panel.
Just to get more information, are you using Meshtastic firmware?
