Arlo Pro 2 + Powebank - constant power consumption

[Arlo_User2020]

Good Morning

I have Arlo Pro 2 in place (indoor) and would like to charge the cams (I left the battery inside cam) via a PowerBank (Adata PowerPack P20000D). Charging works fine so far - battery status of cam show 100% with a lightning symbol.

Here is the problem:

I use my cams ONLY for live video, when I connect to it. No motion detection, nothing. So basically if nobody is connected, no power should be used. This worked fine so far. Now I connected the Powebank (20000mAh) to the full loaded battery of the cam. Within 10 hours 20% of the Powerbank is gone although nobody connected to the cam! This is more mAh than the whole battery of the cam has. Do you know what is wrong here?

My assumption is that if the cam is connected to a power source it uses much more / permanent power for any reason. 

Or do you think this is a powerbank issue?

Did anybody make the same experience and/or have an idea how I can fix this?

Thanks for any hints and replies.

Kind regards

Michi