I need to understand what runs off the main car battery and what runs off the 12v battery
I am newish to my Prius Hybrid 2018 Bus Edition model.
A few months ago, the 12v battery went flat because I’d been charging my phone in the car while the engine was switched off. I was in the middle of the countryside. The AA repair person changed the battery for me showing me the old battery was only 4volts or something and very bulged so at the end if its life. He put in a decent 12v battery.
I’m now not sure what could risk draining the battery. Listening to the radio? Front doors being left open for a couple of hours because of the little lights in them? Charging my phone? Anything else?
Basically, I don’t understand when the main electric battery that drives the car is in play and what the 12v battery does. Can anyone help with this?