We also have a solar system and generator and have never had a battery issue. We run out of water and propane before we lose electricity. I think its an investment worth considering if you plan to do a lot or any dry camping. We live in Washington State where its gray most of the day.
If one does any boondocking at all, I highly recommend going with multiple batteries. Some go with pairs of 6V deep cycle golf cart batteries. Others with 12 volt batteries in parallel, because if one has a fault, it can be unwired, while a 6V battery that dies will kill the pair.
I personally like AGM batteries, because they don't need water added, and don't vent when charged, so are safer all around. However, you can pick up a deep cycle RV battery for about $100 at an auto parts store.
I'd read up on posts, to see what people do, and also shop around.
No matter the size or type of battery, amps used are amps used. It is like the size of your fuel tank.
The aim is to cram as many amps into the available battery space of the trailer. It matters little whether you do it with 6V in series or 12V in parallel. After you have done that how long they last is up to you & your understanding of what uses how much power. You need to do a bit of educating yourself on the differences in batterys. There are batterys designed for starting & batterys designed as 'house' batterys. There are 3 main types of batterys, all having advantages & disadvantages.
Walking up & buying the cheapest thing on the shelf will likely see you back at that shelf much sooner.
Boat: 32' 1996 Albin 32+2, single Cummins 315hp
40+ night per year overnighter
From what I've seen, parasitic draw varies quite a bit between different units. My Springdale TT draws somewhere between an amp and an amp and a half per hour just sitting there with the refridgerator on gas. If it has a door heater there isn't a switch for it, and it sounds like there is a fan that kicks in on hot days for the exhaust, but I haven't tried to get back there to see where it is. For us, we find we can generally go for a three day weekend on two group 24's without running the generator.
That said, more often than not I run my inverter generator for at least half an hour in the mornings so the DW can use the curling iron and hair dryer. Since I have to fire it up anyway, If we have the time and can leave it running an hour or more each day we get enough juice back in the batteries to keep us from having any issues.
Quote: No matter the size or type of battery, amps used are amps used. It is like the size of your fuel tank.
and it is a very small fuel tank!
Lead acid batteries have about 12 usable watt hours per pound of battery. That means a group 24, which is typical in smaller RV's, has about 550 watt hours usable while a group 27 about 650 and a T105 about 725. Note that these ratings are for about a watt of power draw per pound of battery. Larger draws will reduce the available energy.
Figure maybe 10 watts for residual (alarms, control boards) so that's 240 watt hours per day. An incandescent bulb is about 15 watts, a typical RV fluorescent light is about 30 watts, The furnace is up to 100 watts.
The upshot is that a battery can go real quick if you aren't careful. Adding more or bigger batteries might help some but not so much in real terms.
Try to avoid letting your battery go below 12.2v as measured after a half hour or more of no significant charge or discharge if you want best battery life. Always keep it on a good maintenance charging system when not in use that will maintain a full charge and apply a sulfation inhibiting technique for best service.
As mentioned by some one else in passing, conservation use of LED's and in our case I use three speed computer case fans instead of a Fantastic Fan, about 1/10th the power draw. Care and feeding of a deep cycle battery and preventing its early demise by for instance not letting it go below 50% depth of discharge. This also means you need to monitor your battery, this can be as exact as A Victron or Trimetric batte4ry monitor or as simple and monitoring the battery voltage.
The best single source of information is www.batteryfaq.org
I have a single 150AH AGM 12V Lifeline battery and 320W solar
Deep Cycle batteries will last a long time if you use a smart-mode converter/charger unit and never ever let your batteries get below 10.5VDC charge state. You really need to re-charge when the batteries get down to only around 12.0VDC which is considered 50% drained.
My three GP24 deep cycle batteries are on their fifth year now and still going strong.
When camping in the woods off the power grid the rule of thumb is generally one battery one night. Of course if you watch what you are doing you can probably stretch this out a bit but generally for conversation purposes one battery one night would probably be a good rule to follow. There are several thing you can do to make camping off the power grid a great experience.
I found that not just "ONE THING" will do this for you as you have to look at the whole battery system as a whole to be successful at it. The idea being you can survive the one night off the battery system and then be able to re-charge the batteries in a short 2-3hours the next day by connecting your trailer shore power cable directly to a 2KW generator and run that for the 2-3 hour time period to re-charge your batteries. Then you are good for the next night etc....
Been doing this for three seasons now and we are very successful camping off the power grid. When we get setup at camp site off the power grid, we just run an 120VAC extension cord from the trailer to whatever we need power for sitting around the camp fire..
My Posts are IMHO based on my experiences - PM me Roy and Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
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2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS
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Years ago I bought a 1977 Pace Arrow 27 foot Class A.
Our first trip in it was to a back-country primitive area, where there were no hookups, and the altitude resulted in night time temps of less than 40 degrees. The coach battery was an 8D battery, one of the huge truck/industrial types.
With the thermostat set at 55 degrees, it went dead at 3 AM! I had to get up and start the engine to get enough power to start the generator. It was COLD in there!
In our current RV (see sig), with two Trojan T-105 batteries, we have gone 4 days with minimal generator run time, and no furnace use. No problems.
So, I guess MY battery lasts anywhere from less than overnight to 4 days or so...
It depends!
CM1, USN (RET)
2002 Fleetwood Southwind 32V, Ford V10
Toad: 2006 Jeep Rubicon LJ
Other toad: '06 PT Cruiser, Kar Kaddy dolly
Toy: 1977 Dodge W100 CC SWB, 3/4 ton axles & springs
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