Just upgraded to 6 volt

pnichols wrote:
unless one old dying member of two old 12s dies as a near SHORT - instead of a near OPEN (as is probably the most likely case) - you still have one old 12 left supplying some 12 volt power ... unlike with one old dying member of two old 6s.

I was thinking of the short, where that failing battery quickly takes down the other one. Also, there's no more risk in having one 6v die than there is in having a 12v battery die. And if you lose 1 of your 12s you're probably going to the battery store soon anyway. And you shouldn't be running your batteries into the ground in the first place!

If you're actually *planning* on running your batteries until they die, then yes, get 12s.

All this is moot anyway as the risk is SO small, and choosing 12 over 6 because of it is ignoring the 99.9% of the time how you'll be using them. Sorta like not going camping because you may get in a wreck.

2oldman wrote:
Theoretically, but the chances of a normally healthy 6v battery just up and dying are miniscule. Now, if you run your batteries for years beyond their normal lives, then yeah, one is likely to die first.

Virtually the same risk exists for parallel 12s.

I disagree on "Virtually the same risk exists for parallel 12s."

Unless one old dying member of two old 12s dies as a near SHORT - instead of a near OPEN (as is probably the most likely case) - you still have one old 12 left supplying some 12 volt power ... unlike with one old dying member of two old 6s.

The 6 (golf cart) versus 12 (true deep cycle) discussion always boils down to one of money, as ... "two or more deep cycle 6s is always cheaper than two or more deep cycle 12s". (I'm talking new purchase here - not lucking out by finding and purchasing two or more still good used true deep cycle 12 volters.)

Deep cycle apples to deep cycle apples comparison is often missing in the discussions. :S

As I pointed out perhaps a dozen years ago...

"Well, you can't have everything"

Choose wisely the battery type that will offend you least...

MEXICOWANDERER wrote:
3 cell flooded GC220 batteries have two traits and two traits only that make them special.

1) Greater number of life cycles than 6 cell car jar batteries

2) Significantly more forgiving to mistreatment

FORGET AMP HOUR COMPARISONS! Like comparing a fast car to a comfortable car to an economical car. Apples and hand grenades.

It depends which "12v" you mean, but for the usual "deep cycle/starting" 27s like I had a few years ago, there is a third BIG difference---recharging them to "full" It was like pulling teeth to get the SG up in those 27s, even by tipping them over etc.

With 6s it is so easy--charge them up and their SG rises no problem. Gottaluvit. However, my 12v T-1275s are more like 6s for recharging and getting their SG back up. The T-1275s are also better with big inverter draws than my 6s, so they are the winners for my way of doing things.

I have two AGMs now in the truck camper, but have not enough experience with them to compare with the others. They do certainly hold up better under inverter loads than the 6s. Maybe just a bit better than the T-1275s. However, I don't really like not being able to see how it is going with recharging them, operating in the blind (no SG checking) I don't like that they may or may not need an overcharge and I can't tell. However, since they have to be inside the camper where flooded batts would be a gassing fumes problem, I will just have to live with that.

I also did not like paying over the top for a 100AH battery just because it is AGM :(

MEXICOWANDERER wrote:
People who demand high performance inverter/microwave performance should seriously consider high CCA AGM batteries which in that mode will kick the snot out of any flooded battery of equal size and weight.

The problem is that most RV'ers learn via the school of hard-knocks. They design, they build and come up short.

But if a boondocking microwave is in the future for you, and battery space is limited. Forget flooded anything. 2 group 31 AGM batteries will markedly outperform 4 Trojan T-125's. The word MARKEDLY is not used loosely here.

Forgot to add: The AGM will blow a flooded 31 in the weeds as well.

The posts immediately above are great by the way. I thought I'd amplify and elaborate.

Agree completely. We do use a microwave, a panasonic true inverter that varies magentron power rather than cycling on and off. at 50 percent power needs about 80A. Running this off two GC is an excercise in frustration, as you point out. unless they are near 85 percent or more charged, the voltage drop will kick off the inverter. with 4GC it's good to around 60 percent. But then we only occasionally run the microwave, and when used for a few minutes at most. so living with the GC drawbacks given how we boondock is in our case a reasonable accomidation. But it is not a good fit for this few percent of our use, but we know how to live with it.

yes, those 4 trojan t-125's I have won't even give the cranking amps ONE of my 65A diesel truck batteries gives. And they aren't AGM's.

But if you like lots of draw often, and long periods, I agree completely. GC for sure are the WRONG choice for that application,

3 cell flooded GC220 batteries have two traits and two traits only that make them special.

1) Greater number of life cycles than 6 cell car jar batteries

2) Significantly more forgiving to mistreatment

FORGET AMP HOUR COMPARISONS! Like comparing a fast car to a comfortable car to an economical car. Apples and hand grenades.

People who demand high performance inverter/microwave performance should seriously consider high CCA AGM batteries which in that mode will kick the snot out of any flooded battery of equal size and weight.

The problem is that most RV'ers learn via the school of hard-knocks. They design, they build and come up short.

But if a boondocking microwave is in the future for you, and battery space is limited. Forget flooded anything. 2 group 31 AGM batteries will markedly outperform 4 Trojan T-125's. The word MARKEDLY is not used loosely here.

Forgot to add: The AGM will blow a flooded 31 in the weeds as well.

The posts immediately above are great by the way. I thought I'd amplify and elaborate.

ktmrfs wrote:
Lesson: determine what YOUR application is, and pick the battery configuration best suited to YOUR application. No ONE perfect solution for every application..

x2.

Much better to design for performance rather than failure.

MEXICOWANDERER wrote:
The ratio of under warranty batteries failing was something like 50 car jar 6 cells for every genuine Trojan T105. Or 50 to 12 for Us Battery GC220 3 cell units. All flooded batteries. Even the 6 cell Trojan car jars had an unacceptabally high warranty rate. I sneaked around from the counter (friend warrantying an Interstate battery at a distributor. I grinned at his warranty pallets. I got caught by the owner (open air loading dock) Threatened to call the Sonoma County sheriff. Probably less concerned about his wife and kids. Touchy touchy issue.

If you look at the trojan cycle life chart the 12V deep discharge batteries have much lower cycle life than the 6V, AND are recomended to not go below 50 percent SOC.

but they are better if you want to drive heavy inverter loads. first they have much lower internal resistance, second your usually sharing the load with twice as many 12V banks.

Lesson: determine what YOUR application is, and pick the battery configuration best suited to YOUR application. No ONE perfect solution for every application.

In my application cycle life, and deep discharges were top of the list, followed by occasion heavy inverter loads, 5 minutes or less. But that meant I needed 4 GC to satisfy the later. So that is whatI ended up with.

The ratio of under warranty batteries failing was something like 50 car jar 6 cells for every genuine Trojan T105. Or 50 to 12 for Us Battery GC220 3 cell units. All flooded batteries. Even the 6 cell Trojan car jars had an unacceptabally high warranty rate. I sneaked around from the counter (friend warrantying an Interstate battery at a distributor. I grinned at his warranty pallets. I got caught by the owner (open air loading dock) Threatened to call the Sonoma County sheriff. Probably less concerned about his wife and kids. Touchy touchy issue.