Suncontrol Board cutting power - even though it should not

Question/help require on Suncontrol board shutting down power supply to Weather station.

Station itself is described here:

Please be gentle with my graphs. I am still fine-tuning the layout

Battery is loaded:

The Weird thing is that the battery load went down - which it should not have, as nothing is supposed to drain it.
And - with the Solar panel charging it - it should even go up.

System was charging the battery nice:

Battery Voltage:

Sloar Panel Voltage went up a little over 5.67 volts before it happened (well, last measurement that was pushed to the DB. We have a blid-spot Monitoring situation here - means in betwen the points, we have no data).

That the power was cut can be identified by 2 things:

- When the SkyWeather python script performs a low power shutdown, I get a Mail and the shutdown is clean.

enable_WLAN_Detection = False

It is not the first time it has done this, and I wanted it to happen when I have more data available.

To identify it has to be the Suncontrol board shutting power - I opened the Weatherstation and the only board that showed power was the Suncontrol board. All other boars who usually have a blue light showing were dark. And the PI itself was Dark too.
LKogs show nothing as these go onto the the /var/tmp/log directory which is ram-based and synced to disk every 3 hours only.

At the time of the shutdown, nothing special happened. PI was on regular load:

How can I troubleshoot further?
Any advice apreciated.

PS: You can see the entire Monitoring page here:

and the Weather Station SkyCam / Currently on my Terasse:

I am in the process in receiving the 5.6V 10W Zener Diodes - I'll hook up to the Solar Panel - that should prevent Voltage Spike situations (If that is it). Buit I have nothing else so far to troubleshoot this.