AGMs

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Mile High

Mile High

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Joined
Oct 17, 2016
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985
Location
Denver
Well winter wasn't nice to my AGMs and they are flat.  Perhaps the coach batt disconnect doesn't completely isolate them or perhaps they were abused before we owned it, but I can tell you the coach is really limited without them (can't start gen or inverter).  power fades to off within a few minutes of shutting off diesel.

I have the 6 AGMs between the frame - does anyone know the series of battery Winnie uses and is there a favorite brand out there?  Just trying to shop before I head back out to the campground.
 
Whether AGM or flooded, no lead-acid battery can survive a winter season without at least periodic charging. You can't just leave them in the rig, even disconnected. They will self-discharge over time.

6v deep cycles are size GC2. Some rigs have room for the slightly taller GC2H size and can gain some additional AH capacity using them. The GC2H is 11-5/8" tall instead of 10-5/8".
 
The six AGMs that Winnie installed in our coach were sold under the Napa brand, and were manufactured by East Pen. Yeah, those are gonna be pricey to replace - sorry about that Brad. I also learned the hard way that batteries last much longer in storage if they're kept fully charged. Fortunately, I didn't learn that lesson with my expensive AGMs.

And for what it's worth, I never use the house-battery disconnect switch. It doesn't truly disconnect the batteries from all loads, and even an amp or two of continuous parasitic loads will drain the batteries in short order.

Kev
 
If you are a member, Sam's Club and Costco are good sources for 6v GC2 batteries, AGM or flooded.  Tractor Supply Corp stores are another good one.

Local golf cart shops are sometimes a good source. They have the batteries, and some of them charge reasonable prices to get high sales volume. Others just charge what they think they can get from golfers.

If you don't get Trojan or Lifeline brand, it doesn't make much difference what the label says cause they will all be made by one of the big US battery manufacturers and labeled as the buyer requests. US Battery and East Penn or proably the largest supplier of AGM 6v GC2 size batteries, but Exide and Johnson Controls make their share too. There is no meaningful difference among them. Trojan and Lifeline (aka Concord) are the premier deep cycle brands, but usually premium-priced too.
 
It won't help Mile High out, but if anyone lives in the mid-Atlantic area, Pasco is also a good place to buy batteries. They also do starters, alternators, and work on golf carts, among other things.
 
Gary RVer Emeritus said:
Whether AGM or flooded, no lead-acid battery can survive a winter season without at least periodic charging. You can't just leave them in the rig, even disconnected. They will self-discharge over time.

6v deep cycles are size GC2. Some rigs have room for the slightly taller GC2H size and can gain some additional AH capacity using them. The GC2H is 11-5/8" tall instead of 10-5/8".
Click to expand...

Well Gary this isn't my first rodeo, but after 40 years of leaving lead acid batteries in my RVs and Boats, this is the first year I found a dead battery in the spring.  There must be a shadow draw on the coach batteries so I'll have to figure out how to disconnect them next winter.
 
Kevin Means said:
The six AGMs that Winnie installed in our coach were sold under the Napa brand, and were manufactured by East Pen. Yeah, those are gonna be pricey to replace - sorry about that Brad. I also learned the hard way that batteries last much longer in storage if they're kept fully charged. Fortunately, I didn't learn that lesson with my expensive AGMs.

And for what it's worth, I never use the house-battery disconnect switch. It doesn't truly disconnect the batteries from all loads, and even an amp or two of continuous parasitic loads will drain the batteries in short order.

Kev
Click to expand...
Kevin,
How did you disconnect your AGMs?  Did you go into the compartment or do it back at the relay in the left rear?
 
Gary RVer Emeritus said:
If you are a member, Sam's Club and Costco are good sources for 6v GC2 batteries, AGM or flooded.  Tractor Supply Corp stores are another good one.

Local golf cart shops are sometimes a good source. They have the batteries, and some of them charge reasonable prices to get high sales volume. Others just charge what they think they can get from golfers.

If you don't get Trojan or Lifeline brand, it doesn't make much difference what the label says cause they will all be made by one of the big US battery manufacturers and labeled as the buyer requests. US Battery and East Penn or proably the largest supplier of AGM 6v GC2 size batteries, but Exide and Johnson Controls make their share too. There is no meaningful difference among them. Trojan and Lifeline (aka Concord) are the premier deep cycle brands, but usually premium-priced too.
Click to expand...
Gary, I see Sams out here lists the Duracell 31series.  Would that be the same as the US Battery or East Penn?
 
Use an ammeter to determine your phantom load. It should be maybe a few hundred milliamps  (hopefully much less than that.)  If it's a bunch, figure out who's the bad guy.  If very little phantom load, you could have had one cell go bad in the bank and that one bad cell can bring down the entire bank. One of the hazards of batteries in parallel.

Your AGMs have very low internal resistance and shouldn't self discharge very quickly but I have no idea how long they would last in those conditions.
 
Mile High said:
Gary, I see Sams out here lists the Duracell 31series.  Would that be the same as the US Battery or East Penn?
Click to expand...

The Duracell AGM31DC's I have (from Sam's a while ago) are manufactured by East Penn.
 
John Canfield said:
Use an ammeter to determine your phantom load. It should be maybe a few hundred milliamps  (hopefully much less than that.)  If it's a bunch, figure out who's the bad guy.  If very little phantom load, you could have had one cell go bad in the bank and that one bad cell can bring down the entire bank. One of the hazards of batteries in parallel.

Your AGMs have very low internal resistance and shouldn't self discharge very quickly but I have no idea how long they would last in those conditions.
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Thanks John.  Typically the motorhome would sit for 30, sometimes 45 between runs this last summer, and even when I ran it in November after sitting nearly 90 days the coach batteries seemed fine.  It was that 6 months that may have brought them down too much from whichever load it had on them.  I may be able to get them tested to see if I have bad one in there, but they sure wasn't very responsive charging off the running diesel.  90 mile run and they lasted about 60 seconds. 
 
Mile High said:
Kevin,
How did you disconnect your AGMs?  Did you go into the compartment or do it back at the relay in the left rear?
Click to expand...
Brad, the only time I've ever disconnected my house batteries for more than a few minutes, was when I was installing two additional house-batteries, and when I was installing our solar setup. In each case I physically disconnected the battery cables from the battery's terminals. I've used the battery disconnect switch a couple of times, but only for a few minutes to run some tests. When our coach isn't in use, the batteries are connected, the disconnect switch is on (connected) and the charger is on.

Kev
 
Kevin, you were right, they were NFPA 9831DT batteries, still had the Winnebago part number tags on them.  Tried charging and testing, but they were toast.  Finding six in town kind of took the fun out of shopping, so I settled on some East Penn AE8A31 AGM's at our Itasca dealer that also is the Freightliner service center.  The batteries had the same specs as the NAPA and we're competitive at $231 I guess.  Up and running but man I'm glad I'm done moving them batteries around :).
 
Gary RVer Emeritus said:
The 31AGMDC is 12v, not 6v.

The Duracell 6v AGM is model GC2AGM. I'm not sure who makes the 6v AGM battery for the Duracell brand label - it is not necessarily the same as the other models. 

https://www.samsclub.com/sams/duracell-agm-golf-car-battery-group-size-gc2agm/prod3870119.ip
Click to expand...
Gary RVer Emeritus said:
The 31AGMDC is 12v, not 6v.

The Duracell 6v AGM is model GC2AGM. I'm not sure who makes the 6v AGM battery for the Duracell brand label - it is not necessarily the same as the other models. 

https://www.samsclub.com/sams/duracell-agm-golf-car-battery-group-size-gc2agm/prod3870119.ip
Click to expand...
Mile High said:
Kevin, you were right, they were NFPA 9831DT batteries, still had the Winnebago part number tags on them.  Tried charging and testing, but they were toast.  Finding six in town kind of took the fun out of shopping, so I settled on some East Penn AE8A31 AGM's at our Itasca dealer that also is the Freightliner service center.  The batteries had the same specs as the NAPA and we're competitive at $231 I guess.  Up and running but man I'm glad I'm done moving them batteries around :). :)) Yep those 31's are 70 pounds apiece.....my back hurts thinking about 6 of them!!
Click to expand...
 
Mile High said:
... Tried charging and testing, but they were toast.  ...
Click to expand...
Ah-ha! So now the mystery of being discharged is solved. I'm a bit surprised they went badly so quickly relatively speaking. I replaced my Lifeline AGMs at seven years of age just because I don't like to get surprised with spontaneous failures. They were still fine (and got about $50 from a metal recycler.)

Speaking of weight, I'm not sure I want to try replacing mine again with my tired old back.
 
It sure is awkward on the back inside the basement but my daughter was able to stand up on the ground inside the opening and hand them to me.

My batteries may have been dicharged for several months.  Add that to freezing weather..... i think i murdered them.
 
Glad you're up and running again Brad. Ouch! on the cost though. We've got 8 of those things in our house battery-bank and, so far, they're doing fine, but I'm sure not looking forward to the day I've got to replace them. It'll probably happen at the same time my tires come due.  :eek:

Kev
 
Mea culpa. I thought Mile High originally stated he had 6v batteries, but what he really said was "6 AGMs" and did not mention any voltage. Sorry that I confused the responses with all that 6v stuff.
 
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