changing from 2 12volt batteries to 1 12v battery

Know your needs. If you seldom dry camp, all you need the battery for is something to power the lights and have enough oomph to actuate the magnets for the breakaway mechanism. Batteries are not cheap, and if a single small battery is good enough, so much the better.

There are a lot of people who dry camp, but if you don't need a beefy battery capacity, more power to you. It just means more stuff that needs maintained.

Thousands of people get along fine with a single group 24 battery for what the OP proposes. That is, until we read on here how much we are abusing our batteries and that we need four times the capacity to survive. March is "Baby your Battery" month.

steelhead63 wrote:
I am thinking on changing from 2 27 series batteries to 1 31 series interstate battery. We seldom dry camp except when spending the night at a Walmart when we're traveling to and from our snowbird location. Most of our inside lighting is LED. I am wondering if this 1 battery will be enough or should I stay with 2 12 volt

With what you say that you only dry camp in the occasional Walmart parking lot and have mostly LED's, there is no reason you can't remove one and free up space/some tongue weight. With the draw of LED's, even if you left them on all night you would likely be safe. From your post and being in the confines of a Walmart parking lot, my guess you won't be there long enough for it to be an issue, even if you used your furnace...

Also, unless your 27 batteries are bad, it is a waste of money to upgrade to a 31. Just keep your old ones, and put the money into upgrading the remaining incandescent bulbs.

Finally, everyone's usage is different and while you say it is "just lights", it will put you at ease to test this. The easiest way is to disconnect the parallel connection and connect just one battery. You can do this in the driveway, or if that is not possible/feasible, just leave both batteries on the trailer connecting same as above, but now give it a real world test at Walmart. Should that fail, you have the second battery as a backup. Check your voltage the next morning and if all is well, now you can go home and remove the 2nd battery and clean it up. BTW, if this is a Deep Cycle or Marine battery, they can be run down to 20% without issue. Many confuse this with a regular battery that should not be taken below 50-40%, otherwise it will reduce life drastically.

If you ALWAYS camp with an electric hookup you can get away with a 12V lawnmower battery just for the emergency break-away switch.

mbopp wrote:
I have 2 G29 batteries & removed them for the winter. Since it looks like we won't be doing any extended dry camping I'm only going to install one of the batteries this spring. I figure even if we do one dry overnight I should be OK.

westend wrote:
For sure, one Grp 29 will get you through one night.

A more efficient way might be to use both batteries since you will draw down two to a greater SOC. That should result in more charge cycles (longevity) than using one and leaving one in storage. There is also the theory of using one and leaving one floating so that, in the future, you have a fully usable replacement. An alternative, also, is replacing both with GC2 6V batteries and using a disconnect switch. The storage life of a GC2 6V pair is pretty high. Only the most abused and ill treated 6V batteries will not survive a long Winter. That alternative means no battery carrying is necessary. You could also rig up a small solar panel to have the ultimate "hands free" setup.

ALL of which is overkill for those of us including the OP who rarely camp without shore power. The better solution - K.I.S.S. ... one battery, size of your choice from G24 to G31. :B If you're at all concerned about back up simply set up your truck to load support the trailer those times you may deem it necessary. For me, that's when we lose campsite shore power and I want to use my inverter to run our coffee machine and toaster. Since I'm powering the inverter with a single G27 voltage drop is excessive under heavy load but load supported with the truck idling it's a non-issue. If I were dry camping regularly I'd unquestionably run 2 G31s or 2 GC-2s but for occasional use load supporting with the truck is much simpler. Pics are in my gallery starting here. :)

mbopp wrote:
I have 2 G29 batteries & removed them for the winter. Since it looks like we won't be doing any extended dry camping I'm only going to install one of the batteries this spring. I figure even if we do one dry overnight I should be OK.

For sure, one Grp 29 will get you through one night.

A more efficient way might be to use both batteries since you will draw down two to a greater SOC. That should result in more charge cycles (longevity) than using one and leaving one in storage. There is also the theory of using one and leaving one floating so that, in the future, you have a fully usable replacement. An alternative, also, is replacing both with GC2 6V batteries and using a disconnect switch. The storage life of a GC2 6V pair is pretty high. Only the most abused and ill treated 6V batteries will not survive a long Winter. That alternative means no battery carrying is necessary. You could also rig up a small solar panel to have the ultimate "hands free" setup.

The reason I suggest the "hands free" alternative is that I always have hated carrying batteries. That attitude is not diminishing. I've probably schlepped more batteries than the average guy from my work experience. You get to know what works and hope it doesn't involve me too much, lol.

FWIW, I have 5 batteries at present in my system, split into two banks. All of them are being maintained by a solar panel. Solar, with a good programmable controller, does a better job than I can with multiple 120V chargers.

I have 2 G29 batteries & removed them for the winter. Since it looks like we won't be doing any extended dry camping I'm only going to install one of the batteries this spring. I figure even if we do one dry overnight I should be OK.

We use only one(1) g 27 for even night after night if needed on very long trips.Batt. is full charged after a day's drive.

landyacht318 wrote:
So you had ~230Ah capacity with two new fully charged healthy group 27s, and you need to know if 130 AH capacity is enough.

BUt we have no idea how much AH capacity you require, occassionally.

So nobody can answer your question without a bunch of supposition and guessing.

Sure we can - the OP has already qualified his reliance on battery power, saying it's restricted to the occasional overnight at WalMart, otherwise he's running on shore power. Although the OP never told us the make / model of batteries he has it's doubtful a pair of G27s would offer a 20 HR rate of 230 AH, more likely around 90 AH apiece. An Interstate G31 which he mentioned as a replacement would buy him a bit more at ~ 100 AH (20 AH rate). For his application that single Interstate G31 would serve his purposes just fine. FWIW, I run a single Interstate G27, even have a 1000 watt PSW inverter for those times we may lose campground shore power, and when I do eventually replace it I'll most likely do so with a single G31 which is totally sufficient for those of us who normally camp with shore power. :)

To the OP, I agree completely that a single G31 will work just fine for your intended application which limits your "dry camping" to an occasional overnight at WalMart. You can also draw from your truck for a short duration as well if you find that G31 drawn down a bit more than you'd like.