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Old 02-08-2016, 12:39 PM   #15
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1955 22' Flying Cloud
1964 17' Bambi II
Clear Lake Shores , Texas
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I purchased a VmaxTanks AGM battery through Amazon:
So far so good.

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Old 02-15-2016, 08:35 PM   #16
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2015 28' Flying Cloud
Charlottesville , Virginia
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Thank you to everyone who replied to my original post! I want to install the batteries that I finally purchase in the battery storage box that is mounted on the A frame by the LP tanks. I am confused as to whether to replace my wet cell batteries with AGM batteries or with another set of standard wet cell batteries. I store my 2015 FC in a storage facility with no electricity so slow discharging AGM's would be nice. I like the idea of no maintenance and the slow discharge that AGM batteries offer, the price of $250-$300 per battery is a deterrent. What should I do? What brand of either type should I purchase? Where do I get the best price?

Bald Eagle
28 Ft. Flying Cloud
2015 GMC Diesel
Charlottesville, VA
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Old 02-15-2016, 08:54 PM   #17
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2015 30' Classic
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I'd go with flooded batteries and either remove the negative battery terminal before storing your trailer or add a disconnect switch to make this easier.

Here's some recent recomendations for batteries.

On page 3 of this thread you'll find info regarding the disconnect switch if you're interested.
Al, K6IV
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2014 RAM 2500 w/Cummins Diesel
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Old 02-15-2016, 09:09 PM   #18
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Upgrade Converter

Would recommend replacing the factory installed Parallax converter to a multi-stage converter. This alone will ensure that your batteries (AGM or flooded) last longer and provide peak performance. I just replaced the factory installed Interstates with AGM to include a new PD4655 converter. Next up... SOLAR!
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Old 02-20-2016, 06:10 PM   #19
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Charlottesville , Virginia
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Ok fellow AS'ers here my newest dilemma in buying new batteries for our AS. Someone posted that Interstate Batteries and now carried at Costco so I went to Costco to check it out. I trust Costco but there is a difference in Costco Interstate Batteries and the ones that came with my AS. The two Interstate Batteries that came in by 2015 28ft. FC are Deep Cycle Marine/RV batteries and have the following information written on them - part number SRM 24, Marine Cranking AMPS 690, Reserve Capacity 140 the. The batteries at Costco say Marine RV/Fitment Code 13 Group Size 24DC, CCA 550, 140 Reserve Capacity. They only have a one year warranty vs. the two year warranty that the Interstate Batteries that came with the RV have and the Cold Cranking AMPS on the one that came with the AS are 690 CCA vs the ones at Costco which are only 550 CCA. I'm stymied and don't know whether to buy the ones at Costco (seem like a great value $73/each or go to an Interstate Store and purchase the exact same batteries like I already have at a much higher price. How much difference does 140 CCA make? One other difference is that my Interstate Batteries have Green label on them and the ones at Costco have a blue label. Can someone help me with this?
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Old 02-20-2016, 07:53 PM   #20
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Originally Posted by Rgentum View Post
One downside is that I didn't see how to install two Group 27s in the battery box that came with the trailer. Consequently, I mounted them in the storage area under the queen bed & rerouted the battery cables, which turned out to be a pretty simple job. I've removed the threaded rod in the battery box, which has now become an additional, if small, storage area.
I just purchased 2 new group 27s to replace my 24s (lifelines). Here is how you can install 2 group 27s in the standard battery box. Installing lead acid batteries inside the coach without external venting is a no-no (evening if they are sealed AGMs / maintenance free):
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Old 02-20-2016, 09:10 PM   #21
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Cold cranking amps are meaningless in a trailer application as you aren't cranking anything...

The reserve capacity is the same for both and that is the key number. If the price is right at Costco, I'd go for it.

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Old 02-21-2016, 05:33 PM   #22
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My local Costco sells Interstate Group 27 batteries for approx. $75 each --- but they are flooded, lead-acid, deep-cycle batteries; I've asked if they sell AGM batteries or can order them, & they don't & can't. The Group 27 batteries I installed under the bed were Group 27 sealed, AGM batteries, at approx. $200 each.

I fussed & fussed trying to figure out how to install Group 27s into my battery box, & at least with the Group 27s & the battery box I had, the only way I knew how to do it involved cutting off one or more of the top lips of the box, which I rejected; maybe others have a larger box?

I acknowledge that others have opined that installing sealed & unvented AGM batteries inside the trailer "is a no-no." To obtain further information on this issue, I did a Google search on "must AGM batteries be vented?" & found:


The batteries do not have to be in a box but if they are, they should be vented as per ABYC recommendations. AGM's are SVR (sealed valve regulated) batteries.


A vent system or other means shall be provided to permit the discharge from the boat of hydrogen gas released by the battery.

Battery boxes, whose cover forms a pocket over the battery, shall be vented at the uppermost portion of the cover.

NOTE TO 10.7.9 and 10.7.10: These requirements also apply to installations of all batteries whether they employ removable vent caps, non-removable caps, are “sealed” or “maintenance free” batteries, or have pressure regulated valve vent systems with immobilized electrolyte (gel batteries).

Location of Batteries and Battery Charger (see ABYC E-10, Storage Batteries). Consideration should be given to the following:

- Adequate ventilation should be provided to the bank of batteries to limit the temperature rise during the charging. Sealed valve regulator batteries do allow escape of hydrogen gasses during overcharging; therefore, SVR batteries require the same precautions for ventilation as wet (flooded) batteries. During the charging process, fully enclosed battery boxes will result in a greater temperature rise than with an open battery box.

2. From

There are two primary types of VRLA batteries, gel cells and AGM. A VRLA battery (valve-regulated lead–acid battery), more commonly known as a sealed battery or maintenance free battery, is a type of lead-acid rechargeable battery. Due to their construction, they do not require ventilation, can be mounted in any orientation, and do not require constant maintenance. The reduced venting is an advantage since they can be used in confined or poorly ventilated spaces. They are widely used in large portable electrical devices, systems and similar roles, where large amounts of storage are needed at a lower cost than other low-maintenance technologies like Li-Ion.

3. From

Never install any type of battery in a completely sealed container. Although most of the normal gasses (oxygen and hydrogen) produced in an SVR battery will be recombined and not escape, oxygen and hydrogen will escape from the battery in an overcharged condition (which is typical with any battery type).

For safety's sake, these potentially explosive gasses must be allowed to vent to the atmosphere and must never be trapped in a sealed battery box or tightly enclosed space!

4. From

Article 480.9 of the National Electrical Code (NEC) states that provisions for ventilation must be made to prevent the accumulation of explosive gases, but the NEC doesn’t go into the specifics. Under the NEC, sealed battery technologies don’t require venting. American Boat and Yacht Council (ABYC) guideline 10.7.9 recommends a sealed, vented enclosure no matter what the battery type. Some local electrical codes even require power venting of the battery enclosure.

A properly designed and installed power system with a modern, three-stage charge controller keeps hydrogen gas emissions to a minimum (as with your present system), and battery technologies like sealed lead-acid don’t gas during normal operation. But what happens when the situation becomes abnormal? A poorly programmed or malfunctioning charge controller can cause any battery to gas, and even “sealed” batteries have internal valves to release the gas and prevent a case from rupturing.

__________________________________________________ ____

Here's my situation:

a. Yes, I have installed 2 Group 27 AGM batteries in the storage area under the bed, adjacent to the front storage area accessible immediately in back of the old battery box & propane tanks.. These two areas are open to each other; the plywood that separates them only goes up partially to the top of the storage area, allowing air in the two areas to intermix. The front storage area is not sealed --- it is partially open to the outside. The storage area under the bed is also not sealed --- it is open on both sides to the bedroom area. Therefore, the AGM batteries are not in a "sealed battery box" & vent into both the interior & the exterior of the trailer

b. The two batteries are strapped to the floor & covered on their top by a cover (without sides) that is also strapped to the floor. The AGM batteries are not in a container, sealed or otherwise, so any discharge from them vents into the storage area, which is open to the interior of the trailer & partially open to the exterior of the trailer.

c. When I replaced the lead-acid batteries with AGMs, I also replaced the stock converter/charger with a 3-stage converter charger, specifically made in part to charge AGM batteries, to ensure no overcharging.

All in all, I remain unconvinced that given these circumstances, more venting of the sealed AGM batteries with no battery box is either necessary or recommended.
Alta & Richard, Seattle area --- WBCCI 8873
"Aurum": 2018 Ram/Cummins 3500
"Argentum": 2016 AS FC 27 FB
"BigDog": M Harlequin Great Dane, 150 lb
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Old 02-21-2016, 06:49 PM   #23
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Installing a Progressive Dynamics 4655 and two 6-volt 220AH Lifeline batteries in series was one of the best upgrades I've done.

I believe it was Lester who recommended this years ago.

Not ready for lithium yet. I have found the Lifeline 6-volt configuration works well for our use.
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Old 02-21-2016, 07:20 PM   #24
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You pretty much nailed it with the ABYC E-10 standards. Remember that these are written for the marine industry and the many enclosed spaces found on a boat, but I follow them as closely as possible, along with E-11, A-25 and A-31.

AGM batteries (I will address only Lifeline AGM batteries here, as they are the only ones that I install, other than lithiums) will typically only out-gas in extreme overcharge or over temp. conditions. Under normal charging situations with the use of a quality 3-stage automatic charger (and more specifically with a fully programmable inverter/charger with full temperature compensation), any gassing that is a normal by-product of proper charging is automatically re-combined into the glass mat material and does not open the one-way pressure release valve found on each AGM battery.

The only times I have seen this valve open is during prolonged over-charge episodes (above 15.5VDC for extended periods) or in extreme heat situations (ambient temperatures above 75ºC with no temperature compensation on the charge voltage).

I have placed many battery banks in similar locations to the one you are intending to use with no ill effects. You should have no issues.

Lew Farber...ABYC Certified Master Marine Electrician...RVIA Certified Master Tech ...AM Solar Authorized Installation Center...AIRSTREAM Solar & Electrical Specialist...Micro Air 'Easy Start' Sales and Installations
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