Battery bank upgrade.

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Manitou
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Battery bank upgrade.

Post by Manitou »

Think this has been covered elsewhere, but I did the upgrade today. Swapped the pair of old conventional wet cell group 29 batteries for (3) AGM group 31's from same club. (Got a free 1 day pass somehow at the counter).
Bought 2 19" 4ga battery cables from autozone to add in the other battery.
Batteries=$600 even with trading in the 2 old ones for core charges ($18 each).
Battery cables $13(? Close enough but kind of forget)

Had to try 2 different sams clubs before finding 3 of them.
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Manitou
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Re: Battery bank upgrade.

Post by Manitou »

Pic is after removing the slider tray. Seems like we could fit even taller batteries though? Maybe there's a group 31 "tall"?
Removing the tray is 4 bolts. Those bolts were very rusted on mine. I think some of that was due to Battery acid. All 4 broke pretty easily with a socket and socket wrench. Then a couple pound hammer sled thing beat them out with 1 wack each.
I took the chance to clean up the compartment. (Dust pan/broom and then a wet shop towel).
Pic shows the battery orientation I used with 1 battery missing from the pic still. You get the idea.
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Re: Battery bank upgrade.

Post by Manitou »

The first SAMs club did have 2 AGM 31's that only claimed deep cycle. But then it still had cranking amps on the label. And they were $20 more. It made me think they are the same battery essentially when I saw the cranking amps. I heard of it lists that, it's not a true deep cycle. I'm not sure who to believe what.. But bigger batteries and 3 instead of 2 should be a marked improvement. The old batteries were (only) 3 years old, but have been through extreme temperatures (Texas/Florida heat and Colorado/Tahoe cold).
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Blue~Go
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Re: Battery bank upgrade.

Post by Blue~Go »

I sure wish Sam's Clubs in the west had those Group 31 AGM's - very good price on those in the eastern Sam's Clubs.

There are no Group 31 talls. Probably because Group size corresponds to physical size (so making them "tall" would defeat the purpose). 6 volt batteries are generally tall, but then of course you can't use odd numbers.

There are "plump" Group 31's though. They are plump in amp hours, not in physical size. For example, I got Lifeline Group GPL 31XT's. These have 125 amp hours. I asked them how they "stuffed" the extra amp hours into the same case size, and they said that, essentially, each plate has two sides and mates with the next plate, and so with the standard batteries, the end plate has no mate. For the Group 31XT's, they cut a plate in half and put the half plate in so the end plate has a mate. Hence the additional amp hours (and a bit more weight) but the same case size.

I was thinking the Group 31's might stand on end in the battery area (with the tray removed), but that doesn't necessarily gain you anything except a different arrangement of filled space and empty space. I decided to put mine under the couch so never tried it, but one reason I went with the three Group 31's is that I knew I could fit them in the outside locker if I wanted to, and I wanted all the options going into it.

I have also heard about "real deep cycle batteries don't give CCA ratings," but I don't think it is true. The spec sheet for my Lifeline batteries gives a CCA rating, and they are definitely deep cycle batteries not starting or multip purpose ones. From Lifeline's web pages:

"GPL-31XT is designed for Deep Cycle RV / Recreational Applications"

And from their marine page:

"GPL-31XT is designed for Deep Cycle Marine Applications."

Yet in the specs they list CCA figures:
CCA.png
So I think that, in and of itself, is not indicative.
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Re: Battery bank upgrade.

Post by Manitou »

Ahh.. Well there wasn't 3 of the "deep cycle" labeled ounces available anyway. I could have gotten 2 from the first store, but none at the second. The second had 5 of the marine dual peyote ones though (first store had 2 of those also).
I saved $60, but more importantly.. still got a decent upgrade in my opinion.
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Blue~Go
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Re: Battery bank upgrade.

Post by Blue~Go »

Oh I agree! I think maybe what I said came out wrong. I'd be thrilled to have those Sam's Club batteries available out west. What I was trying to say was that I, too, have heard the "thing" about how any batteries that list CCA are not deep cycle batteries. And I can see the logic in that, as they don't typically crank, so why rate them for such?

However, as shown by Lifeline's specs, true deep cycle batteries do list CCA, at least sometimes. So seeing CCA ratings isn't conclusive one way or the other.

I agree: Nice upgrade to your Chinook!
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Manitou
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Re: Battery bank upgrade.

Post by Manitou »

No worries man..
$600 for batteries still felt like a lot to me. I guess it's not a lot to more experienced RV'ers though. How much were the lifelines if you don't mind my asking?
I could have gone the cheap way out and just fitted 2 new lead acid group 29's. The temps I spend time in justified the AGM's in my mind.
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Re: Battery bank upgrade.

Post by Manitou »

I wonder if there's some setting I should change on the progressive dynamics charger I have? Better look into that now.
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Re: Battery bank upgrade.

Post by Blue~Go »

IIRC, mine were $372 each - that's with free shipping included. They are slightly "larger" at 125 amp hours, but still, Lifeline aren't cheap.

When I was drooling over those Sam's Club batteries (that I couldn't get out west) I remember them as something like $150 apiece (so seriously cheap!), but maybe I'm remembering wrong or they have gone up.

I would say you definitely want to be charging those new, expensive (and fantastic) batteries properly. Here is what I would do:

1) Look up the Battery manufacturer's specs for the charging stages. They may call it different things, but basically you want to be looking at "absorption" and "float" (or whatever your mfgr. calls those stages). Bulk comes before those, but there is no setting as at that point you are throwing whatever you can at them. However absorption and float are very specific on AGM's, and you want to heed that. If there is only one rating, it's usually at 77ºF. Lifeline gives a table for a large range of temps. Looking at the variations, you can see why you want to be sure to have a charger that has temperature compensation (typically a small lead that goes to the batteries so the charger is charging according to battery temp, NOT according to the temp where the charger is (which is what it will do if not temperature compensated).

Here is the Lifeline table, just so you can see (but different batteries have different specs, so don't go by this for non-Lifeline batteries).

Oh wait, I can't upload a .pdf, I forgot (any way to enable this?). At any rate, for example, at 60º Lifeline recommends absorption voltage be 14.56, and float voltage be 13.54. At 80º, absorption 14.27, and float 13.25. So you can see it varies quite a bit even over a 20º range. With batteries in an outside compartment, you'll likely see more variation than that (at 30º they show 15.1 absorption, and 14.08 float).

So, step one is to make sure you have a charger that can accommodate both temperature compensation (then hook up the lead) and the settings you need. They make some that fit into the stock space, but I decided on a stand-alone charger that I preferred the specs on. At any rate, don't just use the stock one, presuming it is a "stupid" charger as most RV stock ones are.

I would also review your over-current protection. A bank of three Group 31's can bank some SERIOUS short circuit power, and many fuses (even if the fuse rating itself is the right size for your wire) do not have the AIC rating to accommodate that. What that means is that the fuse holder or fuse body itself will self destruct and you have no protection.

As an example, my three Group 31's have a combined short circuit rating of 12,771 amps. That is huge, and even Blue Sea's "Marine Rated Battery Fuses" are only rated up to 10,000 AIC. Thus I had to go to a Class T fuse (rated up to 20,000 AIC). This is not about fuse size itself (which goes by wire size). I have just a 225 amp fuse in the Class T, so nothing hugely special, but the AIC rating is what drove my fuse style selection. (Wire size drove the amperage of the actual fuse.) The fuse should be right at the battery (or as close as you can get it), because any wire between battery and fuse is not protected against short circuit by that fuse.

My Chinook came stock with a LONG #8 wire running from the charger to the battery tray (up over the window and then back down). Lots of voltage drop (which renders your careful charger settings moot) and not really able to fuse adequately for wire size. I'm replacing that with a shorter, larger gauge wire. Not through the long route they took over the window, but along the back-side of the couch (protected in a sheath, although that is a fairly protected location anyway). As you probably already know, with DC wiring (especially at 12 volts) long wire runs are killer, and the shorter the better.

If any of this sounds like Greek, ask away. I'm not an electrician, not even close, but I think I understand the basics and will help if I can. And too, others here may be more qualified. If you want to read the pro stuff, then ABYC has the gold-standard standards published.
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Re: Battery bank upgrade.

Post by Manitou »

Yea you went over my head. I emailed progressive dynamics:
"I converted to your pd4655 some time ago for my old group 29 lead acid batteries (2 of them). I just upgraded to 3 AGM group 31\'s yesterday. Any setting I should change in the pd4655? If so, how exactly? Thanks"

"You should be good with the factory setting.

The charger comes from the factory set for.

AGM and Lead acid.



Service Department
Progressive Dynamics
8A.M-12PM & 1PM -5PM EST
Phone 269-781-4241
FAX 269-781-8729"
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