Ok I have heard this so many times and now I figured I would get more opinions! I was told by 3 different RV stores/ Shops that putting 2- 6Volt batteries in Series will give me more Amp Hours than 2- 12Volt batteries in Parallel. They tried explaining to me that if you put them in series the voltage and a.h. will go up and I said I don't think that is how it works for 6volt batteries in Series. When something is in series you get double the Volts but the amp hours stay the same.. I have a good understanding of electronics and how it works. What is your thoughts and experience about this? Do you have 2 12v or 6v batteries? Is this different because of the deep cycle batteries? I want to get more run time out of my deep cycle batteries.

I am wondering some of the same things. 1 thought that comes to my mind is, if I have 2 6v batteries and 1 goes bad, I have nothing.If I have 2 12v batteries and 1 goes bad, I have less amp hours, but my rig will still operate.Not much help to you I guess. I'll be watching the replies.

dockmasterdave wrote:I am wondering some of the same things. 1 thought that comes to my mind is, if I have 2 6v batteries and 1 goes bad, I have nothing.If I have 2 12v batteries and 1 goes bad, I have less amp hours, but my rig will still operate.Not much help to you I guess. I'll be watching the replies.You are right I forgot about that part if one fails you are dead in the water! I did get 2-6V batteries because I figured they are the same batteries in my UPS units so they will not go to waist no matter what. GREAT POINT!

I use two 6-volt GC batteries, because they are true deep cycle & are better suited to the duty cycles they are subjected to. I also carry a single 12-volt, as back-up.I dry camp 100% of the time.

The two Interstate 12 volt deep cycle batteries that came with our motorhome lasted less than four years. I replaced them with two Trojan T-105 6 volt deep cycle batteries in June 2007. These batteries are still going strong after eight years. I don't worry about failure of one 6 volt battery, as deep cycle golf cart batteries are widely available.I don't know the difference in amp-hours, but the Trojans definitely can run the furnace much longer without getting to 50% discharge compared to past experience with the 12 volt Interstate batteries.The Trojans are larger (taller) than my old 12 volt batteries and are heavier. I figure that more lead in a battery means more amp-hours.

Amphours are amphours whether they are from a 6 volt jar or 12 volt. Wired in series battery voltage is added together and amperage remains same, and with paralleled batteries voltage is constant and amperage is summed up.Most 6 volt GC batteries are roughly 210 to 225 amphours, and most 12 volt batteries range from about 85 to 115 amphours depending on group size. Under most circumstances, a pair of 12 volt batteries will have very similar amount of amphours as a pair of 6 volt batteries. The difference lies in their construction and design. I've had both 6 and 12 volt set-ups and found that our pair of 6 volt GC batteries are proving to be more resilient when deeply discharged and are better capable of taking the abuse of camping off the grid.Our current set of 6 volt GC2 Interstate batteries purchased from Samsclub are still providing good, reliable service going on 5 years. I had good success with our 12 volt setup albeit with shortened longevity. With either choice how they are charged and maintained makes all the difference.

2 Camper Batteries 12V or 6V | Good Sam Community

35 Replies

pnichols
Explorer II
Jun 29, 2015
Muddydogs wrote:
I check into this quite a bit recently and came to the conclusion that 6 volt battery's have a few more AMP hours then 12 volt and most say they last longer but in the end I stuck with 12 volt battery's. The reason I stuck with 12 volt battery's is I can find 12 volts about any place so if I need to replace while in some remote area I can. If I have a problem with the truck battery I can pull a battery off the trailer to get going.
Now some of the above posters will repeat that a battery failure is unlikely but I find most of my battery issues crop up when the temp drops in the fall and considering that I go from 70 degrees in town to some times 20 degrees in hunting camp the chance of having a problem is there with my rig or another's rig. Had one battery failure in a pickup in the last 3 years so it does happen.
Then there is the option of adding battery's to my trailer battery's for an extended stay. With 12 volt I can add another battery without a problem but with 6 volt I would have to add in multiple's of 2.

Excellent post ..... and some very good points!
KJINTF
Explorer
Jun 29, 2015
Might want to consider a different route
4 each 400amp/hr 3.2Volt LiFePO4 cells in series
Me I'm not at all worried about a cell failure
Muddydogs
Explorer
Jun 29, 2015
I check into this quite a bit recently and came to the conclusion that 6 volt battery's have a few more AMP hours then 12 volt and most say they last longer but in the end I stuck with 12 volt battery's. The reason I stuck with 12 volt battery's is I can find 12 volts about any place so if I need to replace while in some remote area I can. If I have a problem with the truck battery I can pull a battery off the trailer to get going.
Now some of the above posters will repeat that a battery failure is unlikely but I find most of my battery issues crop up when the temp drops in the fall and considering that I go from 70 degrees in town to some times 20 degrees in hunting camp the chance of having a problem is there with my rig or another's rig. Had one battery failure in a pickup in the last 3 years so it does happen.
Then there is the option of adding battery's to my trailer battery's for an extended stay. With 12 volt I can add another battery without a problem but with 6 volt I would have to add in multiple's of 2.
I guess I like to be prepared as much as possible and not have my head stuck in the sand, 2 trips ago I ended up making a 200 mile trip to find propane hoses that run from the regulator to tanks as both mine started to leak in 20 degree weather. Ended up purchasing a regulator and 2 hoses as they didn't have the hose with the regulator fitting I needed. This was on a 7 month old trailer.
pnichols
Explorer II
Jun 29, 2015
MEXICOWANDERER wrote:
There is no converter in the fricken world that will float the Lifeline or any other AGM at theoretical perfect voltage when ambient temperarures exceed 80F.

However (there's almost always a however), when one wants to charge a Lifeline or any other AGM battery using only a converter's ~13.6 volts when ambient temperatures exceed 80F - then things begin to happen regarding a healthy current flow.

There may be an Old Chinese Proverb that goes something like: "One temperature's float voltage can be another temperature's boost voltage."

We find ourselves desert rockhound boondocking at times. The good old Parallax converter really treats depleted AGMs well then. ;)
pnichols
Explorer II
Jun 29, 2015
MEXICOWANDERER wrote:
Do a float amperage test somtime on a Lifeline and see the amperage difference between 13.4 and 13.6 volts. SURPRISE!

.... that's probably why the Lifeline customer service guy told me over the phone to not have them hooked up long term to no more than a 13.4 volt float level .... cuz above that they begin to "dry out".

Interpreting/extrapolating between his words, his comments told me that intrinsic current flow - after about 13.4 volts - must then begin to shoot upwards on a steeper slope, thus heating things up, thus causing water to slowly but surely vaporize away. Interestingly - as you have noted in other posts - Lifeline changed their tune on their recommended AGM battery float voltages. I used to read it in print at the Lifeline website that one was to use 13.2 volts for floating.

The above (float tune changing by Lifeline) is why I chose Fullriver AGM - who have recommended higher float voltages for their AGMs since day-one. I wanted a 13.5 volt to 13.8 volt recommended float level range that the manufacturer was consistent and open about.

When shopping I didn't know if Lifeline was being too conservative, or if there were indeed some design parameter differences between the two brands that could give rise to different ideal float voltages being required. Note that I said "design parameter differences" ... not construction quality differences .... as IMHO the electro-chemisty versus material shapes/spaces/types used just may be tweekable enough so as to be able to approximately set non-drying float voltage to different levels by design .... having nothing to do with "construction quality or advertising conservativeness".

I'm hoping beyone hope that neither Lifeline nor Fullriver were blowing smoke about float levels, as I'm counting on my Fullrivers not being ruined ("dryed out") by my converter - just as my previous Interstate deep cycle motive AGM batteries were not ruined by my converter.

Of course all applied voltages to any LA battery have different effects at different temperatures. That's why float voltage is specified at a specific temperature ... cuz electro-chemistry behaviors are temperature dependent.
MEXICOWANDERER
Explorer
Jun 29, 2015
Lifeline batteries. Auto or truck. Underhood. 13.8 -14.1 volts CONTINUOSLY for 10-years and at underhood temperatures. Concorde wants their batteries to last 15- years to make them look even better. There is no converter in the fricken world that will float the Lifeline or any other AGM at theoretical perfect voltage when ambient temperarures exceed 80F. Or less than 50F. 13.6 is FINE until temps exceed 100F. Do a float amperage test somtime on a Lifeline and see the amperage difference between 13.4 and 13.6 volts. SURPRISE!
pnichols
Explorer II
Jun 29, 2015
Not all AGM batteries are finicky, and many are designed for true deep cycle use - in both 6 volt versions and 12 volt versions.

Just pick an AGM battery that requires the same float voltage as your converter puts out so that the converter doesn't ruin your AGM battery over time - then use the converter to float the battery when in storage and use the converter, or solar, to charge the AGM when camping (converters work for charging when camping because AGM batteries charge faster on converters than wet batteries do). If you need to charge the AGM battery faster when camping, use a fancy multi-stage charger with hookups or with a generator ... or if you're using a motorhome, drive a few hours to the next campsite with your main engine's alternator charging the AGM quickly.

Pretty simple, really.
Huntindog
Explorer
Jun 28, 2015
EK wrote:
Ok I have heard this so many times and now I figured I would get more opinions!
I was told by 3 different RV stores/ Shops that putting 2- 6Volt batteries in Series will give me more Amp Hours than 2- 12Volt batteries in Parallel.

They tried explaining to me that if you put them in series the voltage and a.h. will go up and I said I don't think that is how it works for 6volt batteries in Series. When something is in series you get double the Volts but the amp hours stay the same.. I have a good understanding of electronics and how it works.

What is your thoughts and experience about this? Do you have 2 12v or 6v batteries? Is this different because of the deep cycle batteries? I want to get more run time out of my deep cycle batteries.

You do NOT add the amp hours when using two 6 volts. Where the additional available amp hours come from is that the 6 volts are taller, so they have more internal volume than a group 24 (generally standard on TTs) battery, and the fact that the 6 volts being true deep cycle batteries can be discharged deeper than the standard hybrid 12 volt that most use.

On most TTs, there is room for two group 24 size batterys in the tray on the toungue. Most have lots of room to go taller, but not wider. So that leaves out 12 volt group 29, 31, etc.
This is one reason why two six volts is so popular.
Plus the 6 volts are much more durable than the widely used hybrids. Then their is the relatively low cost and pretty good availability, and it all adds up to the best bang for the buck.

As for the 12 volt fans concerns about a 6 volt failure leaving them without power.... It is not too likely... Though as 12 volt users, they are probably used to them failing a lot, thus the concern. And of course, if 1 of their 12 volts does fail, they probably won't notice it until the other one is dead anyway.

Most of us that RV for long, will end up wanting better than what is available at Walmart or the local auto parts store.

There are several options.

True 12 volt deep cycle batteries ARE available.
But they are rare, expensive, and heavy.

AGMs. Expensive, and finickey with charging. Make a mistake with them, and it's an expensive proposition to replace them.. Still they have their place. Those with solar, and /or specific chargers swear by them... IMO, they are best suited for those with more than average knowledge of the care and feeding of their batteries.

Lion batteries are getting better and cheaper, but still out of reach for most.

There are quite a few battery geeks here on the forum. They know a lot about how to wring the last bit of performance out of them.
That is great as they seem to enjoy it, and it is good to have that knowledge here on the forum.

But it is more effort than I and many others want.
I generally discharge mine until the converter starts screaming, then fire up the generator. No idea how many amp hours I have consumed, or just what the voltage is when that happens.

I don't care to know. This just works for me. Sure if I was to really get involved in my batteries, I could probably make them last a little longer, but I have never actually worn a pair of 6 volts out.
I have been able to get at least 5 years out of them. One pair had an unfortunate accident, and their replacements were sold with the TT.

When I used 12 volts, it was pretty much a annual replacement ritual.
red31
Explorer
Jun 28, 2015
There is a co with global head 1/4 in PA, they advertise 3 classes of marine FLA battery, one of which they label 'Heavy-Duty Deep Cycle – True Deep Cycle Service',

messenger dons armor!
MEXICOWANDERER
Explorer
Jun 28, 2015
Huuuuu makes a true cyclable car-jar flooded battery?