I have a WittyPi4 + RPi3B+ running on 2 x 12.7V 20Ah batteries (in parallel). The application uses the Witty to wake it up on the hour and every 15 minutes there after to read some Bluetooth sensors and then upload the readings to the internet before powering off (approx. 2mins). This works great and I am getting over 40 days run time. I have noticed recently that when I recharge both batteries and fire up the application again, after the first shutdown it fails to wake up at the allotted time. I always resync the clocks to network time before doing this. Sometimes I have to restart the unit a number of times before it starts to work, and sometimes I just leave it on for an hour without the application running.
I do know the Witty will refuse to restart the Pi if it thinks there is insufficient power to start it. I am wondering whether it might be doing something similar if there is too much power?
Phil
Witty Pi can take voltage under 30V. Your 12V batteries (even fully charged) will not exceed this limit, otherwise the DC/DC on Witty Pi 4 will get damaged, and not just refuse to boot your Pi.
Witty Pi's firmware does not take any action when voltage is higher than a threshould.
When it fails to wake up, is your Raspberry Pi still powered (red LED stays on)? Does the white LED on Witty Pi 4 blink?
When it fails to wake up, is your Raspberry Pi still powered (red LED stays on)? Does the white LED on Witty Pi 4 blink?
The Witty's white LED is blinking, and the Pi only has its red LED on, not the green. I have to disconnect the Witty from the battery to clear this condition and then manually power on the Pi with the button.
the Pi only has its red LED on
That is the problem then: your Pi was still powered, and the shutdown procedure did not finish yet, there is no way it can turn on your Pi again.
The power to your Pi should be cut after the shutdown. It didn't happen for some reason. What is the firmware version of your Witty Pi 4? You can find it in the log.
@admin I am running Issue 7 firmware, as it has the "guaranteed wake up" feature which I have enabled for such occasions. However, if the PI is still powered on the Witty won't do anything. So the weird thing here is why the Pi is hanging during shutdown. I am going to need to look in the logs. And why does this happen only after a Battery recharge? It does feel like this is a Pi issue.
The unit is now working and is about to be deployed to a field trial site for evaluation. When it comes back I am going to have to revisit this again.