I just burned up one of my original Interstate deep cycle 27's. So today replaced them with 2 size 31 Optimas (AGM). Was going to get the size 27, but the 31 fits and has 50% greater power storage.
In the process I discovered that Interstate Battery store will match Sams Club prices, especially when you are in the market for a pair.
For the small amount of boondocking I do this may have been overkill. But we plan a trip to Alaska in a year. Also, they are sealed and require no mtc. other than charging.
I have left my A/S plugged in all winter. Will that be too much for the AGM's?
I upgraded my system last Fall. seems to work fine. In October and March, got two nights from the batteries even with the heater (though the solar was helping)...
Is there any other reason, other than keeping them charged that you stay plugged in during winter storage?
All batteries self discharge. AGM's at a bit lower rate than wet cell types but that only delays the agony.
Batteries sitting around without a full charge means that sulfate has formed on the plates. The longer this sits, the larger the crystals grow. Larger crystals are harder to break up and get back into solution.
The WFCO and PD+Chargewizard do a periodic bulk charge for a few minutes in order to assure that the battery is kept at full charge. This is also an easy way to handle temperature variations for a full charge state. That process also stirs the electrolyte which helps prevent sulfation. This periodic charge bump is kept short enough so outgassing is minimized.
If you have to add water to your batteries more than once in 6 months or so, the odds are that you are overcharging your batteries. This is very common with converters that have little battery maintenance capability.
The battery minder uses a special charging waveform to break up sulfite crystals. That seems to do pretty well and will even provide some recovery of a sulfated battery depending upon how bad the situation is.
I had heard that AGM's did not like equalizing charges or that charge bump thing of the PD+CW or WFCO. PD has a special AGM charge wizard to accomodate that. Recently I have seen where Lifeline says the charge bump is OK. The big deal is to avoid outgassing as the sealed AGM can't recover if it gets overcharged like that. The PD+CW seems to do an excelent job of preventing electrolyte loss in its normal use on wet cells so I'd think it OK on an AGM.
I don't know how the Battery Minder thing would work with an AGM but I'd guess it would probably be useful as AGM's sulfate, too.
I would not keep any battery on a charger as a storage item unless that charger was designed for battery storage management (like the WFCO or PD+CW). Charge it up and then use something like the battery minder to keep it there during storage.
The storage management is also a problem with solar controllers and the better inverters - many of them do not automatically implement battery sulfation inhibition techniques.
yeah, well...over the winter, I bought a "smart" battery charger, on an impulse. The description was much like the super-duper converters that are often touted here. "smart"...special settings for agm, lead-acid, etc...supposed to monitor and shut itself down when charging is complete, cycling to "maintain"..."desulphate" mode.
So I brought my battery (DieHard group 27 lead-acid) inside this winter, like a good doobie, and charged it with this thing. Seemed to work ok. I left it on for a couple of days...then realized that the charger has a fan in it, its using electricity whether I need it to or not, so I shut it off. couple of weeks ago, I fired it up to get ready for the upcoming season. This time, I left in on probably for a couple of weeks.
Well, I went to install the battery last week, and thought I'd better check the water level, just to be sure. the thing was bone dry.
This, after dilligently monitoring this battery for the last couple of seasons, because I'm so scared of my "awful" old ratty univolt from 1973...it never lost a drop of water to that, and I've left it plugged in for "too long" before. (several weeks?). as in "oh, crap, I forgot that I left the trailer plugged in since we came back from camping 3 weeks ago!! I probably cooked my battery!!". well...no. I didn't.
Oh, and last winter (06-07), I just left the battery in the trailer all winter. 5 months later, it was sitting there at 12.6 volts....
But THIS year, I put it on a smarty-pants charger, and nearly killed it. so much for that!
meanwhile, my old yoonie-volt is gently humming away, putting out a nice, steady, 13.5 volts, just like its supposed to....
Oh, and someone mentioned an Optima group 31 -- I thought the "group" sizes were all different among the agm's. The blue-tops I saw at Sam's are definately smaller than the group 27 lead acid batteries. They also say "55 AH" on them, which I assume means "amp hours", while the lead-acids say 115. how is that "more capacity"? I know, you're not supposed to run a lead-acid down below 50%, but even factoring that, the blue top is still not as much. And while you can run an agm down lower, you're still not supposed to run it down to "0", are you?
or am I ...."all wet" here, too?
I just replaced my Delco Voyager 27's which were ultimately cooked by my Univolt with a pair of Wallyworld's "Maxx" 27's. I'm also about to drop in a new Intelli-power converter. I don't intend to do a large amount of boondocking, and I actually like having the option of checking the electrolytes, so I figure that'll do me just fine.
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Cheers, Dave
"Finish." AIR #4188 1994 34' Limited / 2002 Chevy 3500 CC 4x4 D/A Equal-i-zer Hitch / Jordan Ultima 2020
Quick question not ment to change the line of this thread. I have '06 CCD with two 12v batteries wired in parallel from factory. I have just purchased 1000v Yahama to charge batteries while boondocking. I plan to connect Yahama directly to batteries via supplied 12v connectors to charge. The question - do I connect Yamaha cables to one battery (red post to red cable, black post to black cable on one battery) or to both batteries (red post to red cable on batttery #1 and black post to bloak cable to battery #2) since they are hooked parallel?
I didn't read all 3 pages of comments so far, but I am in a similar boat, though my batts are not totally gone...yet. I have been reluctant to buy any type of new battery because of the converter/charger that comes with the Airstream. I am planning on upgrading to something like this before I bite the bullet and get new batteries.
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yeah, well...over the winter, I bought a "smart" battery charger, on an impulse. The description was much like the super-duper converters that are often touted here. "smart"...special settings for agm, lead-acid, etc...supposed to monitor and shut itself down when charging is complete, cycling to "maintain"...
But THIS year, I put it on a smarty-pants charger, and nearly killed it. so much for that!
Chuck,
Have used this "smart" charger for the last two seasons, 24/7 all winter
with the battery's out, have not had to add water and this will be our 4th
season with them.
Would be interested in knowing what brand of charger you used?
It says "black and decker", but it looks very similar to the one you pictured...same buttons/graphics/layout....probably the same manufacturer. I should probably take it back.
I am new to the forum and to Airstream trailers. But I have done a bit with dual battery set-ups in vehicles, boats and small camping trailers. I would like to add a couple of thoughts...
1. Optima used to be a premium battery, but recently they have had quality problems. I have had two successive failures (withtin warranty) on Optima Yellow Top batteries, and currently have six Optimas in my truck waiting to go back to the distributor for the same reason. My distributor recommends the DEKA AGM battery over the Optima, and the DEKA is about $50 less money. I like AGM batteries over flooded batteries because they are lower maintenance, less likely to leak, and have minimal off-gassing.
2. In my light camping trailer - used behind my Landcruiser for long boondock trips, I use two Group 31 105 AH marine batteries and a Guest 2 bank battery tender. I just plug it into 110 and it keeps the batteries in top condition - always ready to go. Deep draw batteries are best charged at low amperage (usually about 2 amps) and the Guest does a great job at intelligent charging and maintaining the batteries. These are tiny - about 4" X 6" X 1" and are easily mounted near the battery. They are available at marine stores - West Marine is a good source.
In general, RVer's can learn and borrow a great deal from he sailboat industry in systems design, electronics, communications and the efficient use of space. The problems are similar, but the sailors operate in a much more hostile environment, so their systems need to be top quality.
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imho, yes. 
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so much for that! 
Would be interested in knowing what brand of charger you used?
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