For me the lithium setup is the way to go and was our long term plan for our Rpod before we decided to upgrade to another RV. They charge faster, deliver almost 90% of their capacity without damage, are lighter and can be stored in the coach without venting. I was going to move my battery bank to the storage area under the bed in the 179, install a DC to DC converter, and replace the onboard converter/charger. Finally, install a plastic tool box on the tongue that would more than make up for the storage lost in the storage bay.

Another downside to Lithium is that in systems with multiple charging options, some of those charging options may not work easily with Lithium batteries.  A couple examples have been brought up in this thread already.  As an additional example, I have a 2nd alternator in my van for charging, it works well for lead-acid but since Lithium batteries (which I have in my van) hold voltage high very deep in the discharge, the regulator on that alternator won't charge until the battery is quite low already, I can't really idle the engine with a half full battery and top it off, the regulator still sees high voltage and won't charge.

Lithium does win vs lead acid on -

Weight per Ah

Usable Ah for a given total capacity as they can be more deeply discharged (one might club this with weight per amp hour and not think of it as a separate thing)

Installation flexibility since the don't out-gas and can be installed inside the cabin without venting concern (nice for keeping them warmer)

Originally posted by Linda&Gino We're being told that the LifePO4 batteries in our new RV will last 10 years as long as the batteries stay between -20F and 115F.

That being said then it makes sense stay with the old technology (lead acid battery) if looking at it from a purely dollar and cents point of view.  My cost so far with an old 11+ year old Interstate (cost when new $ 80 divided by 11 years is $ 7.27/year and will continue to drop as battery ages.  My newer Trojan cost $ 220 back in August 2021 so IF it were to last only 10 years the cost is still only $ 22/year.

Do not know the cost of the lithium battery but I also know you need to change out the converter and that comes at a cost as well.  The cheapest LiPO4 battery I saw was a Dakota for $ 399.  The best price I could find for a converter for a lithium battery was made by Progressive Dynamics which is priced at $ 274.  So . . . . . . . battery + converter = $ 673 and IF it lasts 10 years the yearly cost is $ 67.30/year or over triple the cost of using lead acid and that is if you use the cheapest battery and converter that i found available. 

What is the projected or expected lifespan of a LiFePO4 battery and will that vary due to where you are located; hot verses cold climates?

StephenH - I'm going through your mods list - its fantastic.  The things you have done are things I feel competent to attempt, and I really like the function-first approach you take.  The Great Stuff molding for the hitch box is genius.  I haven't gotten to the battery mod yet, and I'm not going to fast forward, its all great stuff.  Thanks for compiling it all and for referring me there!

Actually, if you match A-Hr capacity, two 6v and two 12v batteries will be very close to the same weight.  The plate area required to get 200 a-Hrs has to be the same.  12v batteries have more cell dividers, so there's a little more plastic in them. 

I had to replace my power center board because it was overcharging the battery and had a large voltage swing.  The replacement Main Boards are almost all WF-8955-AD-MBA that autodetects Li vs Pb batteries and charges accordingly.  It costs about $200 mail order. 

Read my mods, and you will see what I did. I am hoping that the projected much longer lifespan of the LiFePO4 battery will pay off in the long run. Short term, the two 6V GC-2 batteries connected in series is much less outlay, but they do have a shorter lifespan. You would need to determine if you will be keeping your R-Pod long enough to recoup the investment in an LiFePO4 battery. I always thought that if I did change, I could revert the system to stock and move the battery and DC to DC charger to a new trailer.

StephenH -

"when comparing the typical 12V battery with a pair of GC-2 batteries, the GC-2 batteries will be much heavier than a single 12V battery"

This makes sense to me.

I also see that the stock battery on my new 192 is a Marine battery, and I agree with your assessment that it is not true deep cycle.

If I replace it with a 100Ah Lithium (not sure I would, but if I did upgrade, that is likely what I would consider) would the A/C charger be able to charge it, do you know?

There is a difference. Most RPods come with one group 24 size 12V battery. They are so-called marine batteries which are neither full-on starting batteries nor true deep cycle batteries. A GC-2 6V battery is significantly bigger and heavier than the typical battery. I won't argue the point that there are a few 12V batteries that are an exception, but when comparing the typical 12V battery with a pair of GC-2 batteries, the GC-2 batteries will be much heavier than a single 12V battery which is the usual set-up.

An exception is the Trojan 12V battery at 85 pounds. Still the GC-2 batteries are about 60 pounds each so two of them will weigh in at about 120 pounds. That is a lot of lead.

As for if they both were the same size, a 6V battery would have less dividers and likely have a bit more lead, but reality is that they are different sizes. Try to find a 20 hour rating on your 12V battery. You usually see cold cranking amperes, but not the 20 hour rate for 12V batteries.

I am corrected, Jato - thanks!  I assumed without checking that you were talking about a 6V battery.

Now the comparison makes much more sense to me!  I wasn't comparing 6V to 12V at all.

You need 2 of these batteries to get 12V and 150Ah @ 12V, , so I expect the total weight is 170 lbs.  A single 150Ah 12V battery weighs 91 lbs.

The sizes of these batteries are (out of curiosity I looked them up) -

12V - ~1200 cubic inches

6V - ~1000 cubic inches

So if you compare 2 batteries vs 2 batteries, the 12V batteries will weigh a bit more (I am surprised at how little more) and have a almost twice the capacity.  Makes me think I am not understanding something here, I'd expect the 6V batteries to have more capacity than that for the size they are.

This is why we now have a Trojan T-1275 (golf cart battery) better capacity 150 aH and more weight at 85 lbs. This is in addition to the 12v Interstate group size 24 deep cycle battery (11.5 yr. old) kept on the a-frame.  I used to keep a few truck rotors in the front so the tongue weight would be 11% of total weight of the 177.  Now, with the extra battery weight, tongue weight is 340 lbs. and that is with a full FW tank which on the 177 is located behind the axle.  Normally camp w/o amenities so battery life and water capacity are very important.  Added bonus - was able to remove the truck rotors, freeing up valuable storage space.

Comparing two batteries of the same physical size, in general, a 6V battery has fewer cells in it than a 12V battery, so it has fewer lead plates, so it weighs less.  I think you would agree with the fewer cells thing, so I am wondering if I mis-understand your comment or if maybe you have a typo in your comment.

I don't think 6V and 12V batteries will typically be the same size, though.  In systems I have read about, the 6V batteries are a smaller form factor than the 12V batteries being compared against, and the folks decide what to use based on what they have space for.

To the OP, if you replace 2 6V batteries with 2 12V batteries, I'd be surprised if the weight does not increase and the space needed increases.  Along with that, I'd expect your capacity to increase.

This depends on the specific batteries involved, and I'm sure its possible you have 6V batteries right now that are so large that you can find 12V batteries that are lighter and smaller, but I don't think that is typical.

Two 12V batteries will weigh much less than two 6V batteries. The trade-off is in capacity. The only way to beat two 6V batteries is by converting to LiFePO4, which entails a lot of other changes (see my mods for information about that).

Batteries that can be checked and distilled water added if needed are better than sealed batteries that really just mean that you can't do maintenance on them. This applies if you are going to stick with lead-acid batteries.

There is a reason that two 6V batteries have more capacity -- weight. More lead means heavier, but more capacity. Consider the weight though when planning your loading. Those 6V batteries are heavy!

That said, 7 years stored outside, they may likely be at their end of life. 

The terminal you show pictured looks quite corroded. I would clean those up as best you can with a wire brush. Then put some sort of moisture protectant on the terminals before you re-assemble. I use DC4, but there are several alternatives.

After that re-test and see where you're at. I suspect that the batteries are likely done.

Hey Jefferson,  If you have a pair of 6v batteries there is hope, if they are 12v then yes, time to replace, they have been hurt big time.  How old are they? (I can't see from the pic what month and year they were purchased, unless the dealer 'forgot' to do this when the unit was purchased.

As you have read, I have had great success with my 11+ year old Interstate, however have been told that they aren't as good as they used to be.  The other battery recommended (if you are looking at lead acid) are the Trojan line - used on many electric golf carts and is the 'gold standard' for electric golf carts.  I purchased (August 2021) a Trojan T-1275, a heavy weight at 85lbs and puts out 150 aH.  Keep an eye on electrolyte level, don't draw down below 12.2v before recharging and keep posts clean from corrosion. 

I bought one of these battery testers from Amazon and I really like it.

My wife's car was showing signs of needing a new battery, and I decided to buy this when I had the opportunity to use it on a suspected bad battery as well as the new battery in  my car.

It reported the bad battery as "poor" and the new battery as "great".  Checking my so far symptom-free Class B battery, is says "poor", no big surprise after 5 years in Texas weather.