/diy/ - Do It Yourself

I'm about to become a van dweller and want to prepare the interior for living by myself.

Now i didn't do electronics for a long time but i know how to hold a soldering iron, and i'm trying to high-level plan out how to 220v power the van. My current idea is to:

1. Add second (multiple ?) batteries. (do i have to upgrate the alternator ?)
2. Get a generic 1kW 12/220V inverter.
3. Monitor the batteries voltage and turn the engine on if needed to charge.

Now this plan has a shitload of unknown variables so i wanted to throw the ball around with you.

How do i calculate the parameters so i wont drain the batteries in
1 hour if i know i'm using X watts, maybe i can make some kind of "time left at current power usage".

How do I protect from over powering (using too much ampers, not a native speaker).

I imagine i would be using a mac charger once every couple hours (60W), some led lightning (20W ?), and once in a while some high power utility like a microwave or a heater (1kW).

I would be grateful for any tips and thoughts.