Yes, correct, power is shutoff as soon as the car powers down and therefore does not draw any power from the 12v battery.
Interesting that power from parking mode comes from the internal battery, but I wasn't sure if this is kept then topped up from the 12v when in parking mode and could in theory flatten the 12v battery, but hopefully the voltage safe guard it has should prevent that happening?, but I have just been a bit nervous to try it.... but maybe now I will.
I hoped that the camera would record anytime someone crossed in the cameras field of view, but I think it will only record if it detects a bump... am I correct in that thinking?
I am going to get one of those battery monitors when I get back from my holiday as I will be interested to see how the 12v battery performs as I am a very low mileage user. I sold my 7 years old Prius when I bought my NX and it only had 21,000 from new, but it still had the original 12v battery and it was still going strong 😀.