So we've replicated what you're seeing.
There's nothing "bad" going on here, but essentially, you're getting SkyView right up to the threshold voltage where it switches between external and backup battery power. It looks like when you're right near that switchover point (10ish volts) via regulated power, SkyView can end up trying to rapidly switch between the backup battery and external power. You see this as a flickering on the display, as the internal power supply adjusts between battery and external power. SkyView shouldn't do this ideally, but it's not a cause for alarm, nor does it compromise SkyView's backup battery capability.
In a real emergency, an aircraft battery at that voltage would pass through that voltage quickly, and so this shouldn't pose a threat to SkyView operating on the backup battery.
This behavior also shouldn't damage the unit.
We're going to look into tuning the power management software to eliminate this phenomenon in the future.
However, we suggest that if you're using an external power supply to , to use one that can provide power higher higher than 10V (let's call it 12V+, just to pick a number that's well-clear of the threshold) with sufficient current to power the display (about 3.5A at 12V - this changes with voltage, obviously).