Just remember if you are using any 12 volt items when the car is in standby mode only, the 12 volt battery is NOT receiving a charge.
The capacity of 12 volt batteries in many modern cars today ( especially EV’s ) are fairly small.
Reducing size / weight of 12 volt batteries by the manufacturers, is both more cost effective and it cuts down on the overhaul weight of the car.
If I am waiting to pick up from school etc, I just leave the car in ready mode.
When we had our two previous two ZS EV’s I would use a smart charger and just give the 12 volt battery a “top up” helping hand about twice a year.
I also carry a 12 volt battery booster pack under the drivers seat

as a belt and braces approach.
Had it about 4 years and never found it necessary to use on our EVs yet, but it’s has been used a LOT to jump start other peoples ICE cars incidentally

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Definitely worth considering buying one

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