new to rving, resorting camper

I suppose some did have 12v. We had a 16 ft 1972 Holiday, got it in 1984 in NS and towed it across country to BC. (With a 1979 Ford LTD sedan)

I remember it had four fuses in the 120v panel for shore power and that propane lamp over the table in front. Don't remember a battery at all. It had electric brakes and the car had a metal plate above the brake pedal that worked the trailer brakes when you stepped on it. (I guess that got the trailer stopped first now that I think about it) Also had a sliding over kind of lever in a box on the front seat you could adjust the trailer brakes with manually. Same as on a modern brake controller for that part. I never used that ISTR.

The OP could say if that one has original 12v.

EDIT--ISTR you pumped up water to the kitchen sink by hand. Can't remember if it had a shower in the bathroom or how it would have worked for pumping water if it did. It had a real bathroom at the back with a toilet and sani-dump outside like they all have now. Can't remember how the toilet got its water.

EDIT some more--The Ford was an early idea for a Crown Vic, being a tad smaller than the earlier Fords. It had a 351 engine. But you had to be ready to say it was a "Windsor 351" and not one of those phony 351s made in the States somewhere :)

Blf
I really sure that a 71 Holliday has a 12v system

Those were a pretty nice travel trailer at the time

Not a pup not a mobile home

If it was me, I'd make it all 12 volt.
If you don't want to mess w/ or maintain a battery, you don't have to. To operate on shore power, all you will need is a new converter, which does not need a battery,......or even use a battery charger of adequate amperage to operate the 12v items you choose.
If you need to leagalize the breakaway for towing, you can use a 12v lantern battery, as many do on non powered trailers.

OK you have all given me a lot to think about and change thanks.

Those old TTs had only 120 and propane (including a lamp above the table in front), no 12v. Did have electric brakes. But now you need a breakaway system for the brakes so a 12v battery is compulsory. How to keep it charged up? A converter.

With the battery and converter, now you can add 12v things the original never had.

lights etc are already electric
12v electric, the built in converter, should probably be replaced with a new one
if you means residential 120v fridge, many of us have done that, electric heat might get expensive, depending on where you are at, and a propane furnace is always a good back up option, a heat pump instead of the roof top A/C
will give a/c or heat down to about 40 degrees, below that you will need the furnance or other form of heat
and electric cook top or MW is easy to use
I suggest, if your going ALL electric for major appliances and heat
that you get an electrician to install a 50amp RV service, instead of the orginal 30amp service
there is no need and its a lot of trouble, to rewire all the lighting to 120vac
just replace the lights with some 12v LED fixtures and continue to use 12v

with a modern converter 120v to 12vdc, (Not Inverter) different device , you don't have to have a battery,
but IF there is a shore power failure, No lights, No water pump, No furnace, unless you have a battery

an INVERTER uses battery power to create 120vac power for things like the TV, when there is NO shore power or generator
like late at night in a campground with no hookups
or during a power failure
how long you have power depends on how many batteries you have and how much power you are using, you can watch tv for a number of hours, but electric heat or A/C is almost impossible on battery power
so a propane heater or furnace is a pretty god idea for 'Most' people

Usually the lights and vent fans are all 12V in a travel trailer, besides the things others have listed (water pump, various appliances you're likely replacing, the radio if there is one....)

Rewiring the lights for 120V would be a rather tricky process unless you have the walls and ceiling apart already. The existing 12V wiring would not be acceptable for 120V use.

Moved from Forum Technical Support

There are a few systems that are specifically 12 volt. Water pump, furnace fan, etc. Yes you could eliminate the 12 volt circuits, get a 12 volt converter similar to what folks used to use to power a cb radio or car stereo in their homes, but purchasing and installing it will largely consume any savings you may be envisioning.

Restoring, not resorting.