12 to 6 volt batteries

[Airtandem]

I will be needing new batteries on my 2010 FC. From all you gurus, any suggestion as to the amp size and brand, also wet or gel?

[aliner]

I currently have.... 2 Interstate Deep Cycle Extreme 6 volt batteries - GC2-XHD-UTI , 122mins@75 Amps, 232 AH. Had them now for 2 years working in conjunction with my solar. So far great batteries!

Lynn

[idroba]

I have used Trojan T105's for years but the cost has gone up so much I am now using Costco 6 volt golf cart type batteries in both of my trailers. I have only had the Costco ones for a shorter time (3 years and 1 year) so can't tell you how they will be in the long run, but the Trojan's gave me about 10 years. They are wet cell batteries. I take good care of them, proper charging, never over discharged, and never ever let sit in a discharged state for any length of time.

BTW, they are left sitting in the rigs all winter (5 months) with no trickle charge, but the battery totally disconnected after full charge prior to putting away.

[KJRitchie]

Why are 2 6v batteries in series better than 2 grp 24 or grp 27 in parallel?

Kelvin

[kscherzi]

As I understand, if one 12 volt battery starts to fail it will quickly take its partner down with it. In series the two six volt batteries act as one single big battery. I think two sixes generally also have more amp hours. But this may all be hogwash.

[field & stream]

Two six volt (golf cart) batteries have significantly more amp hours - maybe 230 vs. 170. You will have to modify your battery box to allow for the extra inch or so of height. We did this conversion and are glad we did.

[dkottum]

More amp hours with two 6 volt, what's the tradeoff?

[prairieschooner]

Golf Cart type Batteries are actually different in design, we are discussing Flooded Lead Acid type batteries. 2 Trojan t-105 Batteries wired in series have the same Rated Amp Hour Rating as one size 8D but I believe that they give more usable power and last longer.
I thought about trying some Interstate Golf Cart Batteries in my Motorhome although the Trojans were priced very completetively at the local battery outlet. Try getting prices from someone that services golf cart repair facilities, the one I used from Hemet, CA stated that they go through a pallet every day or so.

[Al and Missy]

kscherzi is right. A single lead acid cell has a terminal voltage of around 2.2 volts. A 12 volt battery is 6 cells in series. A 6 volt battery is 3 cells in series. So two 6 volt batteries in series is essentially the same construction as a 12 volt battery except that the cells are bigger, giving more amp hours and the cells are in two cases.

Terminal voltage is subject to many factors, including battery age, sulphation, the self-discharge resistance of each cell. When you put two batteries in parallel, the voltage of that combination will never be more than the terminal voltage of the weakest battery. The stronger battery will discharge into the weaker one until their terminal voltages are equal. No such condition exists with two 6 volt batteries in series.

Al

[idroba]

Originally Posted by KJRitchie

Why are 2 6v batteries in series better than 2 grp 24 or grp 27 in parallel?

Kelvin

The plates in each cell are significantly heavier so the battery holds up better. There is more capacity in a set of golf cart batteries, aprox 220 amp hours vs. 150 for a set of group 24's. Series cells, as in 6 volt batteries connected together charge and discharge more evenly than a set of 12 volt batteries in parallel, giving them longer life. There are only 6 cells to maintain, vs 12. The cost per battery is approximately the same but performance and life are better all around.

The golf cart type 6 volt batteries are taller than the group 24's and 27's so the battery box on an Airstream must be modified slightly. Why Airstream does not do that at the factory is one of the many mysteries of our trailers. In fact why they are not supped with a pair of 6 volt batteries to begin with is another mystery to me. There are virtually no disadvantages, and many advantages to a pair of 6 volt batteries in series vs. a pair of 12 volt ones in parallel.

But then, Airstream still supplies the low quality single stage converter/ charger as it's original equipment unit and no one can figure out why they do that either. I now know that the all in one 120 Volt AC and 12 volt DC units are made by other manufacturers than Parallax but Airstream choses not to install them.

Sigh.

[dkottum]

Does two 6 vdc take longer to charge than two 12 vdc?

[idroba]

Originally Posted by dkottum

Does two 6 vdc take longer to charge than two 12 vdc?

No, with equal amp hour discharge the recharge time should be the same.

[KJRitchie]

6v batteries are typically heavier, aren't they. I think my batteries are about 53lbs each, Interstate RV grp 27.

Kelvin

[field & stream]

6v batteries are heavier. The extra capacity comes from the larger size which means more lead and acid. The Trojan T-105 spec is 62 pounds, which is not significantly more than 12v batteries, and it delivers 225Ah.

[idroba]

Yes, with lead acid batteries, the heavier they are the more capacity they have. Most golf cart batteries seem to have the same weight, right around 62# as mentioned for the Trojan T 105's. The Costco ones I have weigh the same, so should have very similar capacity.

[mjayjensen]

How is the battery box modified? Can you post a picture?
Thanks
Jay

[A W Warn]

My Safari has one 12 v battery mounted on the tongue. I've been thinking about adding a second battery. Is 2 6v batteries is an option on the tongue? I wonder if there is a manufactured plastic box that will work? Does anyone have photos of a tongue mounted 2 battery box with 6v batteries?

[idroba]

Originally Posted by mjayjensen

How is the battery box modified? Can you post a picture?
Thanks
Jay

See my post #18 on this thread:

http://www.airforums.com/forums/f449...fb-124829.html

[idroba]

Originally Posted by A W Warn

My Safari has one 12 v battery mounted on the tongue. I've been thinking about adding a second battery. Is 2 6v batteries is an option on the tongue? I wonder if there is a manufactured plastic box that will work? Does anyone have photos of a tongue mounted 2 battery box with 6v batteries?

Here is a good source of various sized plastic battery boxes:

Battery Boxes from BD Batteries

Since I had the original 2 battery box on my FC 20' I only had to modify the height of the original box and have not really looked at this site too much, but they seem to have a good supply of different boxes.

[TouringDan]

I bought two GTC-2 batteries from Sams about four years ago and paid $72 each. I can easily boondock 4-5 days and never have to worry about recharging them until I plug in after I am home. I carry my genny for insurance, but never need it.

I have thought about upgrading to Lifelines, but can't justify the cost. These common golf cart batteries do just fine for me.

Dan