Do check with your installer on how the battery pack works.
Was considering 24hrs recording. My installer advised me that they usually connect in such a way that the cam draws power from the battery pack when in parking mode. It can last for 36hrs and once the battery pack drains out, the cam will also be cut off. No direct drawng of power from your car battery.
so if you park your car and do not start it for more than 2-3days, there is a high chance the battery pack will drain out and will not record anything after that. Of course, it will be recharge when you start your car and drives it.
But other installer may install it differently. So better check with them.