2022 Salem destination rv has no 12v batteries

[BigDog1333]

Haven't seen posts about destination RVs.
When power goes out a/c thermostats don't reset. Therefore I have to reset manually.
How do I add 12 volt auxiliary to my power supply source?
I guess I didn't explain completely. This destination rv has no batteries installed. Just a converter from 120v.
Just like all RVs, lights,.thermostats and fans run on 23v.
Are all destination RVs like this?

[SAR_Tracker]

I guess the first question would be: What items on the RV are 12v powered? Thermostats in a stick built house are run off a transformer, so they're not really 12v. Lights? Fridge? Water heater? If they are not 12v, then you'll have to have an INVERTER to change the battery power to 110v. And you'll have to have a CONVERTER to charge the battery(ies).