We bought our used trailer about a year ago with old batteries. Took it out a few times and would get about 3 days on two old batteries. It was time for an upgrade.
We chose two 6V golf cart batteries as replacements. Total cost was $335.
I then ordered the Renogy 100 Watt Solar Panel kit on Amazon for $145 on sale. I chose not to install it ON the camper, but instead it can be set up upon arrival of the campsite depending on the sun and shade. I did install the charge controller, wires, etc... But the solar panels can be moved around freely.
Our last trip was 4 days. We ran the fridge for 3 hours on battery to our destination and then switched to propane. We then used exterior and interior lights, water pump, and ceiling fan with no regard for saving energy just to see how it all performed. And when I say no regard, I mean it. We left the ceiling fan on ALL day, our exterior lights were on Every night, we blasted the radio all day...
When we arrived home, our battery registered 12.7Volts. When we left it was at 12.8Volts.
I'm guessing our set up could last a week or longer as long as we have a little sun.
Though it was nearly $500 in total, it was well worth it. We now have a set up that will suit our needs.
A122BH Trailer : Pulled by Jeep Wrangler : Good 'ol SLC Utah