More amp hours in two sixes. Difficult to find a “real” deep cycle 12 volt battery. Trojan makes a one or two deep cycle 12s last time I looked.

6v v 12 20186v v 12 20176v v 12 201712v vs 6v.. which charge faster? 201412v or 6 Dec 20132- 12v or 6v June 201312v vs 6v batteries 201312v vs 6v batteries 2006More 12v vs 6 200612v vs 6v 2010Why 2 6? 2006

Basically 6V deep cycle batteries are constructed for more AH and longer service and hence more suited for off grid use. For pedestal to pedestal or light use camping 12V starting batteries are adequate. For starters a 12V starting battery has about 80Ah+ (160Ah for 2) while 2x 6V have 220Ah.12V marine deep cycle batteries are a compromised starting battery and deep cycle in name only.

You'll read many posts supporting both types of batteries. Things like Amp Hours (AH), plate thickness, Absorbed Glass Mat (AGM)discharge level before damage, etc. But to me it really comes down to a few factors. How much power does the battery have available for me to use. How robust is the battery, and what is the cost or return on investment of the battery. Here's a brief analogy that might help. Picture a battery like the fuel tank in your vehicle. In general a 12 volt battery is a smaller fuel tank than two 6 volt batteries. So in the same vehicle the two 6 volt batteries (larger tank) will give you more distance. If there are many gas stations around so you don't need that longer distance then the bigger tank is nothing more than a convenience. If you are traveling out in the sticks where stations are rare, you'll want a larger tank.So if your 12 volt battery is only used to power the lights and water pump for an hour or so while you pack up camp. And the rest of the time you are plugged in to a pedestal. Then all you really need is an inexpensive 12v battery.If you are off grid, dry camping or boondocking, you'll want a larger fuel tank (battery) You can get the same size fuel tank (battery) in both 6 and 12 volt. But because the 6 volt is used more widely (golf carts and such). The price per size of the tank is lower for 6 volt than comparable 12 volt batteries.

Guy Roan wrote:Off and on I see posts regarding changing out the 12 volt battery to two 6 volt ones. In the past thirty years I have had three trailers and never had a problem with the single 12 volt battery so could someone please explain the reason for swapping to two 6 volt ones.Guyso, my take is that for what you need, whatever type of 12V battery you have been using has served you well, and unless your use pattern changes significantly no reason to change battery types.6V= 100's or even thousands of discharge cycles to 50% SOC or lesslimited high current capabilitygenerally higher cost than equal 12V systemoften longer life in number of yearsmost 12V = lower number of discharge cycles even at 50%high current capability for things like microwave oven etc.generally lower cost, especially when you only need One 12V battery

Educate me on 12 volt batteries | Good Sam Community

valhalla360
Navigator
Jan 31, 2021
Guy Roan wrote:
Off and on I see posts regarding changing out the 12 volt battery to two 6 volt ones.
In the past thirty years I have had three trailers and never had a problem with the single 12 volt battery so could someone please explain the reason for swapping to two 6 volt ones.

Guy

If you stay at parks with shore power, even a cheap automotive battery will do just fine. It would actually be silly to upgrade as you will never use the advantages.

If you are going to be camping away from shore power (and generator), an upgraded battery bank means you don't have to be paranoid about running out of power.
Grit_dog
Navigator
Jan 31, 2021
Guy Roan wrote:
Off and on I see posts regarding changing out the 12 volt battery to two 6 volt ones.
In the past thirty years I have had three trailers and never had a problem with the single 12 volt battery so could someone please explain the reason for swapping to two 6 volt ones.

Guy

Never had problems?
Be more specific. Nothing wrong with a 12V battery. However a statement like that makes me think your camper is plugged in to AC power most all of the time.
profdant139
Explorer II
Jan 31, 2021
I'm with parcany. I carry one 12v battery and a spare. If the battery in use dies or gets too low, I swap 'em out. This is a "belt and suspenders" approach. With two 6v batteries, you've got more capacity, but only as long as both batteries are healthy!

But there is a catch to my method -- this limits me, of course, to the capacity of one 12v. Since these are group 31 batteries, that's a total of 110 amp hours per battery, which means I can only use half of that without overtaxing the battery.

This system works if you are an energy miser (like me) or you have solar (which I do) or recharge with a generator (which I almost never do) or recharge at an RV park (which I do from time to time, especially if we have to do laundry).
time2roll
Nomad
Jan 31, 2021
parcany wrote:
Maybe I am wrong but I agree 2- 6 volt have more amp hours but if one of the 6 volt batterys go bad than you only have 6 volts and nothing in the trailer will work. Yes if your one 12 volt battery goes bad nothing will work anyway.
Yes however a shorted cell in a GC2 seems to be far more rare than a 12v marine battery.
4x GC2 also reduces to possibility of being stranded.
parcany
Explorer
Jan 31, 2021
Maybe I am wrong but I agree 2- 6 volt have more amp hours but if one of the 6 volt batterys go bad than you only have 6 volts and nothing in the trailer will work. Yes if your one 12 volt battery goes bad nothing will work anyway.
pianotuna
Nomad III
Jan 31, 2021
What counts is usable amp-hours.

When inverters were hugely expensive and low wattage the battery format didn't matter much and twin six volts were the best bang for the buck.

Now that 2000 and 3000 watt inverters are common, and relatively speaking cheap, twin six volts are not quite as useful. What were exotic chemistries 25 years ago are now affordable. I know of a drop in 100 amp-hour LiFePo4 for $313 USD.

The ultimate would be Lithium Titonate because they can do 9C. SiO2 would be not shabby either. BL13 could run his 2k inverter at 20% state of charge on a single SiO2--but has since added a 2nd one.

Cost per usable amp-hour is the calculation I would use.

If you don't boondock--then pretty much any 12 volt would be just fine. But so would 2 six volt golf cart jars.
theoldwizard1
Explorer II
Jan 30, 2021
afidel wrote:
It's getting really close already. I can now buy 270Ah of LiFePO4 cells for just over $400 direct from China.

TRUE !

But these are not "drop in replacements" ! They require a Battery Management System and wiring. Also, if you are upgrading from lead acid, you will need a new charger.
theoldwizard1
Explorer II
Jan 30, 2021
Lwiddis wrote:
More amp hours in two sixes.

BEST ANSWER !

Lwiddis wrote:
Difficult to find a “real” deep cycle 12 volt battery. Trojan makes a one or two deep cycle 12V last time I looked.

What most store sell as "deep cycle" dual purpose marine/RV batteries are liitle more than a typical engine starting battery with a different label.

Real deep cycle 12V batteries (Trojan T1275) are expensive and hard to find. The golf cart batteries sold at Costco and Sam's Club might not be the absolute best, but they are the "best bang for the buck" !

If you want AGM, AGM golf cart batteries do exist (6v Trojan T105-AGM, 12V Trojan T1274-AGM). Again, expensive and hard to find.
ktmrfs
Explorer II
Jan 30, 2021
afidel wrote:
time2roll wrote:
Guy Roan wrote:
Off and on I see posts regarding changing out the 12 volt battery to two 6 volt ones.
In the past thirty years I have had three trailers and never had a problem with the single 12 volt battery so could someone please explain the reason for swapping to two 6 volt ones.

Guy
2x 6v is a solution to some issues. If you are good as is then just carry on. You will know when you need something different. Although soon it will be lithium batteries over the GC2 when a better system is needed.
Don't fix what is not broken.

It's getting really close already. I can now buy 270Ah of LiFePO4 cells for just over $400 direct from China. That's cheaper than 4x 220Ah 6V that you'd need to have the same usable capacity (~220Ah with long life), but the lithium solution would weigh about 1/5th as much and fit on the tongue or in a much smaller cabinet space.

four good GC have a useable capacity of (220x2)x0.75= 330AH Trojan T-125's have a cycle life of 500+ cycles discharged to 25%SOC (75% DOD) cycle life approaches 1000 cycles at 50% DDD.

Since most of us TT folks even with lots of boondocking would take years to get 500cycles on batteries, GC can give long life at very deep discharges.

I have gotten 10+ years with 30+ cycles to 25%SOC along with many at 50%DOD out of several sets of Trojan's. And several other camping friends have had similar life with similar discharge profiles.

Still a lot heavier than Lithium!!
ktmrfs
Explorer II
Jan 30, 2021
BarneyS wrote:
Microwave runs on 110v not 12V - unless through an inverter.
Barney

yes, mine runs on an inverter. and two 6V batteries usually will trip out on low voltage at about 80% SOC, four 6V will go for about 50% SOC. While a single or couple of 12V will have much less voltage drop.

Draw is >100A, not a good peak draw on a 6V