12v or 6v?

[Al Bear]

I recently bought a used 22-foot travel trailer, vintage 2007. It has two 12v Group 24 batteries on the tongue. Both need to be replaced. Should I replace them with the same or switch to twin 6v batteries? (Of course, the twin 12v's are currently wired in parallel and the twin 6v's would be wired in series.)
The power center is a WFCO 8900 series with three modes: Bulk, Absorption, and Float.
The twin 6v's would be more expensive but would have some advantages, right? I don't want to go with lithium because I don't want to invest that much in this trailer.

[Defenestrator]

The advantage of the 6V batteries is the ability to handle repeated deep discharges. It's not really an inherent thing of 6V vs 12V so much as what they tend to be designed for. 6V batteries are made for golf carts, which tend to get deeply discharged. 12V batteries are made for cars and boat starting batteries, which get rapidly but shallowly discharged. So the 6V batteries have thick, beefy lead plates and the 12V batteries have thin plates designed to maximize surface area.

So, golf cart batteries (which happen to be 6V) get you more usable capacity for a longer period of time, but for more weight and a higher price.

If you're planning on having plugins, I'd just get a single 12V. If you're planning on doing any boondocking, especially for more than one night, go with the dual 6V if there's room.

[Glenn Baglo]

Originally Posted by Defenestrator

6V batteries are made for golf carts, which tend to get deeply discharged. 12V batteries are made for cars and boat starting batteries, which get rapidly but shallowly discharged. So the 6V batteries have thick, beefy lead plates and the 12V batteries have thin plates designed to maximize surface area.

Not entirely true - a generalization. My Trojan TMX group 27 battery is a true deep cycle battery. It's not a starting battery for cars or boats. It is built for RVs.

https://www.trojanbattery.com/product/27tmx/

[patrick crawford]

i've been running a pair of 6v golf cart batteries for over a year and so far i'm impressed with the performance. yes, they are expensive and heavy but the extra capacity made switching to a 12v/120v fridge in my casita a lot more doable.

p@

[Alex Adams]

If you buy a 12 volt battery, look for ones used in Solar installations. Those are true deep-cycle. My 100Ah 12 volt AGM weighs 64 pounds. I feel it every time I remove the battery when I store the trailer!

[OCJohn]

6v golf cart batteries like Crown or Trojan are the way to go if you do any boondocking. There's a reason golf carts use 6v batteries and not 12. If you're buying two anyway, cost is the only downside. They cost more because they have more lead. More lead = better/longer service.

[Jon in AZ]

6V GC2s have larger cells and bigger plates for maximum discharge cycles. That’s what I’d recommend IF you have room and can handle the weight. They’re about 60-65# each and taller than your G24’s.

If you go with 6V flooded, consider how easy it is to access them to check and add water. 65# of battery is a PITA to get in and out of a tight compartment. For tight spaces 6V AGMs are sometimes used. They’re sealed and maintenance-free, but very expensive.

All share the same limitations common to lead-acid batteries: they should not be discharged below 50%, recharged promptly, and never stored in a discharged state.

[Al Bear]

Thanks for the advice, everyone!
Boondocking: Yes, we rarely have hookups in the campgrounds we use, mostly State and National Parks and USFS.
Space to 2 batteries: Yes. I have 2 batteries already.
Access for adding water: They're on the tongue. Couldn't be easier.
Cost: Good question. Don't know where I will end up on that one. On the one-hand, I'm planning to get solar. On the other hand, we sometimes camp in the redwoods, in deep shade. But we are frugal users in any case.
Weight: I'm puzzled by the mention of weight as an issue. Group 24 12v deep cycle can weight 50 lbs. each. Compared to twin 6v's at 65 lbs. each, that's only an additional 15 lbs. x 2 = 30 lbs. Loaded weight of the trailer will probably be 4800 lbs. Max tongue weight on my Chevy Colorado is 770 lbs. Should I really worry about adding 30 lbs. to the tongue of the trailer?

[Defenestrator]

Theoretically 30lbs could still be the difference between being under vs over the limit, but in this case it's unlikely to be the major factor. Especially since not all of that weight will end up being on the tip of the tongue, so maybe 20lbs of extra tongue weight.

If you're boondocking, it's probably worth the extra cost for deep-cycle batteries of some variety. Either 2x6V or the Trojan TMX24 or TMX27, depending on the size/shape of the space, budget, and what you can find a deal on.

[Eggcentric]

We first started using 6V golf cart batts in 1999 for our first full timing rig.
Bought a rack of Exide golf cart batts for our coach in 2002, they lasted 11 years.
Even put two in our Westphalia, two in our toyota Sunrader, and two on the tongue of our Boler.

[Jon in AZ]

I have a G24 on my Scamp and 2@GC2 in my Class B. The difference is more like 20# each, and a 40# weight difference could be significant depending on the trailer and tow vehicle. We deal mostly with smaller trailers on this forum, so I’m used to thinking in terms of weight and weight distribution.

Sounds like you’re fine both in terms of weight and access, so I don’t see a downside.

[Darrel]

I actually use 2 deep cycle 12v scrubber batteries in parallel. They are about 120 pounds a piece and have a very high capacity rating. Trogen J185H. https://www.batterysource.com/produc...24&detail=true

[Brooks Wade]

I am considering two 6v batteries in series on a new trailer. I use a portable solar panel that clamps directly to the battery posts. Do I clamp onto one battery, or clamp onto positive on one and negative on the other? The batteries will be installed 3-4 feet apart for weight distribution reasons.

[Jon Vermilye]

You need to clamp the positive lead of the output of the solar controller to the positive battery post that is connected to the converter. The negative lead of the solar controller goes to the other battery on the same lead that runs to the negative post on the converter.

In other words, treat the 2 6V batteries as one 12V battery...

[Eggcentric]

Originally Posted by Brooks Wade

I am considering two 6v batteries in series on a new trailer. I use a portable solar panel that clamps directly to the battery posts. Do I clamp onto one battery, or clamp onto positive on one and negative on the other? The batteries will be installed 3-4 feet apart for weight distribution reasons.

Not ideal to space the batts that far apart, make sure you use a thick wire between them.
You connect the negative terminal on one batt to the positive terminal on the second. The external wire between them has the effect of turning the two 6V batts into one 12V batt, so you connect them exactly as if they were one 12V batt. If one is going on the trailer tongue, is is smart to make it the negative so that you can ground it to the trailer and make the other one the positive terminal.
It would be a good idea to find someone local to look over your shoulder, based on your question you need to be very careful.
A couple of weeks ago the village idiot (me) put a dead short across 4 golf cart batts in series at 24 V, before I could get to the disconnect the terminals had turned into puddles, you are dealing with a lot of power.

[Brooks Wade]

Thanks to both of you. I am ordering an Escape and considering their battery upgrade to two 6v batteries. I wasn’t really considering this option until I read the responses to Al’s question.
The photos of Escapes show the battery cases spaced out on the rear bumper and I am trying to determine if my existing solar leads need to reach both batteries. Sounds like they do. I have to factor this into my decision. Now I will contact them on Monday and ask how far they are separated. Thanks again for the information.

[Jon Vermilye]

Originally Posted by Brooks Wade

Thanks to both of you. I am ordering an Escape and considering their battery upgrade to two 6v batteries. I wasn’t really considering this option until I read the responses to Al’s question.
The photos of Escapes show the battery cases spaced out on the rear bumper and I am trying to determine if my existing solar leads need to reach both batteries. Sounds like they do. I have to factor this into my decision. Now I will contact them on Monday and ask how far they are separated. Thanks again for the information.

I wouldn't make my decision on whether to purchase an Escape 17 or battery choice based on the solar leads of your portable panel. If you like the trailer, it is easy to make longer leads. If you dry camp, the additional capacity provided by the 6V batteries is useful.

Better yet, add your own permanent leads to the batteries with an SAE connector (or what ever your portable panel uses) so all you need to do is plug it in.

[Little Richie]

I have an escape fifth wheel. I had 6v lead acid batteries and have switched recently to a 12 volt AGM deep cycle (I cannot remember the group). I may add a second 12 volt. I just wanted sealed batteries. I am tired of checking and topping off. If I forget once...

As noted in an earlier post, you can get deep cycle 12 volt. It seems easier to get less expensive sealed 12 v than sealed 6 v. Neither are cheap. In all cases they are heavier than your typical auto quick start,. Deep cycle, sealed or not, contain a lot of lead.

[Eggcentric]

Originally Posted by Brooks Wade

Thanks to both of you. I am ordering an Escape and considering their battery upgrade to two 6v batteries. I wasn’t really considering this option until I read the responses to Al’s question.
The photos of Escapes show the battery cases spaced out on the rear bumper and I am trying to determine if my existing solar leads need to reach both batteries. Sounds like they do. I have to factor this into my decision. Now I will contact them on Monday and ask how far they are separated. Thanks again for the information.

You need one lead for each batt. but you can connect the positive lead to the pos terminal on one batt, and on the frame on (bright metal) to serve as the connection to the negative terminal on the grounded batt.

[Borden]

Originally Posted by Glenn Baglo

Not entirely true - a generalization. My Trojan TMX group 27 battery is a true deep cycle battery. It's not a starting battery for cars or boats. It is built for RVs.

https://www.trojanbattery.com/product/27tmx/

We went with a m31 house battery it may not be good for starting but it is made for RV's has great life the $700 price and 61 lbs was a lot but has worked well.