How many batteries does your unit have ?

[Windywest]

We bought our 5th wheel slightly used a couple years ago, and it came with a solar panel, charging control panel, transfer switch, Xantrax 2000 watt Inverter, and 4 6V deep cycle batteries. The arrangement works great, can run our entire RV on 110 AC, but was designed for long stays of dry camping or boondocking. Our issue (not really an issue) is that we don't boondock, and haven't stayed at a site without power for the past 4 years.

The batteries weigh an estimated 75 lbs each and take up a lot of room in our front compartment that I could probably put to better use and also reduce some weight. I am thinking I will remove 2 of the batteries and keep them for spares, and the remaining 2 should handle any requirements we might have.

If I did camp without any services, how long would 2 batteries (on average) last with moderate sunlight charging them? the Inverter takes a lot of power but we probably wouldn't use it that much. I would appreciate any feedback before I attempt lifting and straining anything I shouldn't strain. Thanks in Advance.

[SKnight]

It all depends on how much power you use. If you are minimal on lights, with your fridge running, limited water pump use, then you can go several days. If you like your lights, then a day, maybe two. That's only a guess.

If your charging control panel can display amps then you can take that and extrapolate from there. For example, lets assume that your batteries have a combined capacity of 200AH each, 800 total, 50% is 400AH. On a side note, I will be changing to 6V since I have a four battery setup and only about 400AH total.

400AH can run 1 amp average draw for 400 hours, 2 amp average for 200 hours, 5 amp average for 80 hours.

Don't forget, it takes a long time to put that back also. Your typical 10A battery charger will take 40+ hours to replenish it.

As for the solar, you didn't say what the system capacity was but if it's say, 100W then that equates to 8.3A (No factoring for conversion loss since it can vary.) so you'll have an 8.3A charging rate during maximum sun exposure, less as the sun sets or if there's shade.

If you can find out what the typical rate of draw is and what solar system you have, maybe it can be narrowed down some.

[Windywest]

Thanks, looks like I'll have to get up on the roof and see what the rating is on my solar panel and also check the battery AH ratings. My controller is an Enerwatt rated for 30 amps, but the draw from t he panel would never get that high. I notice when the batteries have been sitting for a while, the amp rating on the controller is about 6.5 amps in good sunlight, then slowly goes down as the batteries charge. I suspect the panel is a 100 Watt, and if I can get 3 days out of the batteries without them going flat, that would be all I'd need. I have an older generator, it's heavy and I hate using it in a quiet environment, but if I knew ahead of time that I might be without power, I'd probably take it along. It would be crappy to be somewhere without backup and not have power enough to bring the slides back in.

[SKnight]

I'd suspect they're 100W also. Unfortunately that rating only comes when you can angle the panel directly at the sun, bolted to the roof of a camper means that even at noon they're not quite perfect. But if you're getting 6.5 amps I'd be happy.

Depending on use I'd have to suspect you can get three days easily. Quick way to find out? Camp Driveway, see what happens!

[Windywest]

26' driveway, 30' camper, bylaws are a pain. I'll give it a test before I try with the wife on board for long.

[SKnight]

Originally Posted by Windywest

26' driveway, 30' camper, bylaws are a pain. I'll give it a test before I try with the wife on board for long.

C'mon, HOAs don't feel complete until they can complain about something! Lol!

Do this, with the batteries topped up go one day and night unplugged. Then the next morning check your voltage with a DVOM. Compare to the chart below and see how much you used. That will ball park your consumption rate. Won't be good as actual testing, but should get you on track.

[Windywest]

Thanks for the chart, I use something similar in the winter to check them so they won't freeze, the location and weight don't make them easy to remove. Your chart is a lot better than mine so I'm going to borrow it. Many Thanks.

Edited to add freeze chart in case anyone is wondering about when their batteries might freeze.