# and Type of house batteries

pnichols wrote:

BFL13 wrote:

ron.dittmer wrote:
My personal experience with motor home batteries......

Two smaller 12V batteries will not perform better over time compared to one larger battery. They will when new, but year number 2 will have noticeable degradation. Year number 3, they will be working against each other. Indication of battery mismatch will show up as acid boil-overs.

I do feel that two 6V batteries of a smaller size will perform better than a single 12V battery of a larger size.

To clarify the report, were those two 12v batteries "balanced" as in the loads and charging were "across" the two, or were the loads and charging on one of them with the second battery "downstream"?

BF - good point.

I don't see how a couple of 12 volt batteries connected in balanced parallel can ever have one working against the other. After all, with two in balanced parallel what it seems that you really have, electrically, is six (6) double plate size 2 volt cells stacked in series to produce 12 volts - of greater current capability than only one 12 volt battery with it's hence smaller plate size 2 volt cells stacked in series.

Two 12 volt batteries connected in unbalanced parallel is another situation altogether, since when supplying or receiving current the two 12 volt batteries do not have the same potential across their plus and minus terminals. Over time this will cause different age-related plate and/or electrolyte degradation between the two 12 volt batteries.

I would have not believed it myself so I understand why you both posted your comments.

Our rig has two batteries by design, wired in "perfect balance" fashion. The original batteries were two-12V. Year number 3 was a weak battery year with serious acid boil-overs. Year #4 was a very poor year with serious energy deficiencies. The same exact thing happened with the second pair of 12V batteries of a different brand, paired from a common production month. Each time I pulled the batteries, placed them on a work bench, and monitored their charging as a pair and then independently. I concluded this in each case.

For reasons I cannot explain, one battery would consistently drain much faster, rendering the other battery less utilized. When recharging, the battery with more energy would get fully charged quickly while the other battery never gets fully charged due to it's weakened state. Then comes serious acid boil-overs because one battery gets over-charged while the other never gets fully charged, hence working against each other.

With two 6V batteries hooked up in series, they drain in unison and recharge in unison, a perfect arrangement utilizing 100% of available energy. It is just like stacking batteries in a flashlight that drain in unison.

The last time I replaced my batteries, I switched to two-6V AGM Duracell brand batteries GC2AGM purchased at Sam's Club for a little less than double the cost of 12V lead acid. What a huge improvement in battery reserves on trips along with faster recharge times. I installed them 4 years ago and they are as good today as when I first installed them. With AGMs, the only maintenance is charging. And the battery terminals are always clean.

BFL13 wrote:

ron.dittmer wrote:
My personal experience with motor home batteries......

Two smaller 12V batteries will not perform better over time compared to one larger battery. They will when new, but year number 2 will have noticeable degradation. Year number 3, they will be working against each other. Indication of battery mismatch will show up as acid boil-overs.

I do feel that two 6V batteries of a smaller size will perform better than a single 12V battery of a larger size.

To clarify the report, were those two 12v batteries "balanced" as in the loads and charging were "across" the two, or were the loads and charging on one of them with the second battery "downstream"?

BF - good point.

I don't see how a couple of 12 volt batteries connected in balanced parallel can ever have one working against the other. After all, with two in balanced parallel what it seems that you really have, electrically, is six (6) double plate size 2 volt cells stacked in series to produce 12 volts - of greater current capability than only one 12 volt battery with it's hence smaller plate size 2 volt cells stacked in series.

Two 12 volt batteries connected in unbalanced parallel is another situation altogether, since when supplying or receiving current the two 12 volt batteries do not have the same potential across their plus and minus terminals. Over time this will cause different age-related plate and/or electrolyte degradations between the two 12 volt batteries.

ron.dittmer wrote:
My personal experience with motor home batteries......

Two smaller 12V batteries will not perform better over time compared to one larger battery. They will when new, but year number 2 will have noticeable degradation. Year number 3, they will be working against each other. Indication of battery mismatch will show up as acid boil-overs.

I do feel that two 6V batteries of a smaller size will perform better than a single 12V battery of a larger size.

To clarify the report, were those two 12v batteries "balanced" as in the loads and charging were "across" the two, or were the loads and charging on one of them with the second battery "downstream"?

My personal experience with motor home batteries......

Two smaller 12V batteries will not perform better over time compared to one larger battery. They will when new, but year number 2 will have noticeable degradation. Year number 3, they will be working against each other. Indication of battery mismatch will show up as acid boil-overs.

I do feel that two 6V batteries of a smaller size will perform better than a single 12V battery of a larger size.

RE LifeLine's
ok, tnx that's good to know. I'll look into the prices when I do a swap.

I guess it has thicker plates .
I also have a set of DEKA's.
31 agm's are only 64# ea. at 105 amps. But the Deka Intimidator AGM 8A31DM is really a very good hybrid battery.

Its used as a deep cycle/starting battery as well in marine , truck and
heavy EQ applications and works very well as a deep cycle rv battery.

This Lifeline GPL-31XT Group 31 AGM battery is just about the same size - but a lot heavier - than their GPL-27T, but is rated for a much higher 125 amp hours. This is a serious, but still in a compact group size, 12 volt true deep cycle AGM battery and is really the way to go if one could get a good enough deal on it: https://batteryguys.com/products/lifeline-gpl-31xt

Here's a better price for the GPL-31XT: https://www.thesolarbiz.com/lifeline-gpl-31xt-agm-mobile-12volt-125ah.html

For Anyone interested, the true deep cycle LIFELINE grp 27 agm at 100 amps can fit into many under step wells, I can fit 2 grp 27's . But an AGM can be used inside without venting. Some TC's do that as OEM EQ.


this link is used to show the battery specs, not necessarily the best price.
https://batteryguys.com/products/lifeline-gpl-27t

I have had three GC2 battery banks in the past. The worked well.

My current two group 31 are slightly larger and just as good in terms of durability as the GC2 batteries. The Deka 31's cost more than the GC2's.

I would not change out my two 31's for 2 GC2, I don't want to cut and well the under step battery frame of the MH.

Good Luck!

chistoso wrote:
I have a 2019 Jayco 22' C Class. is it better to have one group 27 battery or two group 24s?

When I upgraded I didn't think I could fit 2 group 27s in my battery compartment so I went with one group 31 and it sure has helped a lot.

GC2s are true deep cycle batteries. Virtually all flooded group 24s are not. If you can fit the GC2s in (height is the major factor) it's well worth the effort. They cost about the same as group 24 but you will end up with about 220 AH vs about 170 with group 24.