Choosing the correct battery. (Flooded or AGM)?

[rtaylor537]

Sorry but I'm a bit tired of searching for an answer, so kindly help if you want.
I have a 2001 30ft Excella in need of two 12v batteries. I have been using the lead acid flooded type for years but have been reading about the AGM type. (And not ready for the lithium type.)
My question is rather simple. Is there any need of changing the charger/converter to accommodate the AGM battery or will the unit installed in my AS suffice.
Or put another way, should I stay with the flooded models. (I'm trying to get a series 31M battery that will more easlly fit in the front battery boxes.)
We seldom boondock unless in a rest area overnight. And when we do I bring along our generator.

[CBWELL]

I have used the old style flooded batteries for years and had no problems. Last pair lasted 8 years, but they require regular maintenance, maintaining proper fluid levels with distilled water, disconnecting when not in use or put on trickle charger. You must also make sure that you have a good 3 or 4 stage converter. The old Univolt chargers that Airstream used were battery killers! We very seldom boondock, and see no real need to spend a fortune on things that we will never use. I "might" put in AGM's the next time if the price is right!

[rtaylor537]

Thanks. I'm thinking like you. Good to know I'm not alone.

[Daquenzer]

You don’t need a different converter/inverter. As to whether you go from flooded to AGM is a personal choice. AGMs are more expensive (I have them) and don’t require maintenance. I put in AGMs instead of flooded, and it is easier.

[sfranklin]

I would not completely rule out lithium, particularly if you boondock. I get it's not inexpensive, but the lithium batteries can last for 2-3 sets of LA or AGM, can be drained to zero or near zero without damage and is roughly 20-25lbs lighter.

As a person who has only had deep cycle LA batteries for roughly 30 years between several coaches, I myself find that I am seriously considering it as I do boondock for a bit over a week without any hookups in remote/rustic areas. As my LA batteries aged, even though they were well cared for, they did start to fade sooner than later after just a few years, most likely because during that 8-9 days, I would have pulled more than 50% out of them, which I am understanding only recently that ages the battery since LA can't really be pulled much below 50%. AGM may be slightly better, but I don't think they can be pulled to near zero without some consequences.

[Bill M.]

The flooded cell will certainly work for your use. The AGM's will provide more power for a longer stay. I was not ready to go to lithium so I put in 2 of the group 31 AGM from Batteries and Bulbs. I use a CPAP and want to be able to do a couple of nights without the generator. They are really heavy. The power converter question depends on what Airstream put in that year. I had the old Univolt and have changed to a more modern charger. If you are not sure about the power converter I would suggest going ahead and changing it. Price wise the lithium have come down a lot. I am going to revisit that decision this summer since I downsized from a 2500 to a 1500 TV this fall and might want to lower the tongue weight a bit. Useful power with the flooded cell is about 70 amp hours with the large AGM about 100 amp hours and with the lithium about 180 amp hours. The AGM batteries are pretty expensive now.

[Mollysdad]

When my reliable Interstate batteries were six years old, I shopped around. It's almost like all the manufacturers of lead acid batteries had played musical chairs and it's impossible to learn where a given battery is made. A web search goes like this: "Johnson controls is an American company started by Fred Johnson in 1922. We produce marvelous batteries in factories all over the world...blah, blah, blah."
I also know switching to lithium is never as simple as swapping batteries.
So I punted and got new lead acid, and added a solar suitcase just to dip my toe in the solar pond.

[sfranklin]

Originally Posted by Mollysdad

When my reliable Interstate batteries were six years old, I shopped around. It's almost like all the manufacturers of lead acid batteries had played musical chairs and it's impossible to learn where a given battery is made. A web search goes like this: "Johnson controls is an American company started by Fred Johnson in 1922. We produce marvelous batteries in factories all over the world...blah, blah, blah."
I also know switching to lithium is never as simple as swapping batteries.
So I punted and got new lead acid, and added a solar suitcase just to dip my toe in the solar pond.

My 21 came with solar, and my guess is AGM, but could be LA, not sure. Pickup the trailer in a few months and can check. The problem with fixed solar, at least for me is that where I go is typically state forest and direct sun, though plentiful, is hard to come by in the enjoyably shaded sites. I guess I could buy a portable and connect it to the "A" frame factory connector. At this stage for me, it's a would like to not need to. If I had the 12v compressor fridge, it'd be another story. But you're right, glad I started this exercise before my current batteries go kaput in a year or two...gives me more time for my head to spin.

[Boxite]

I would (and I do) stay with flooded-cell lead acid. The best value for the money is WalMart EasyStart. A Deep Cycle version (such as a Marine battery) is the best match for an RV.

AGM will NOT guarantee more power for a longer stay. (Sorry Bill..don’t know where you got that..perhaps from advertising)

AGM is merely a lead-acid battery with a permeable “mat” or separator between the cell-plates …instead of flooded cells. The advantage of AGM is they can be turned upside-down without spillage and may better withstand being roughly handled than flooded cell. Their DISadvantage is they should be recharged more “constant current” (slowly…and why some older types of chargers/converters are not the best for them…but despite chicken-little warnings to the contrary..will not ruin them) because their electrolyte movement is restricted by the glass mat…which are purposed to absorb spent electrolyte and gasses produced by the charge/discharge cycle. They are perfect for being stored inside closed compartements (and are why flooded cell batteries are placed outside the cabin or in well-ventilated cabinetry.)
However, flooded cell Marine (as opposed to “Starting” batteries) are designed for rough handling also….they have separators to prevent the plates from being “jarred loose” from bouncing/jarring bumps and wave-action. They are also commonly used in agricultural and off-road equipment for that reason.

Your Airstream will be well-served by the well-proven, reliable flooded-cell battery. KISS.

[uncle_bob]

Hi

Flooded batteries are a good "bang for the buck" way to do things. With AGM's you don't just need "AGM" you also need to get them from a good supplier. It's the combination of good manufacturing *and* the AGM approach that makes them "better". Since AGM by itself costs more, tossing in "name brand" on top of that just drives up the cost more.

When you look at the price of good AGM's vs lithiums, they really don't make a lot of sense anymore. The only two choices that make sense are (cheap) flooded cells or going over to lithium.

If flooded has been working fine for you, stick with it.

Bob

[gypsydad]

Couple thoughts: if you stay with flooded cell (wet cell) or AGM's, with an older AS, you likely still have an older "single stage" converter from AS. This can cause your wet cell batteries to go bad early. Suggest if thats the case, you also consider getting a multi stage converter, to help protect the life of which ever you choose; wet cell or AGM's. (Uncle Bob is right by the way; a properly maintained "wet cell" will outlast the AGM's; several articles on this.)

I am still using wet cell, but I moved from 12V to "2", 6V Trojan T105 model, 5 years ago and have been very pleased with the performance. More usable power for our use model. I also changed out my stock WFCO single stage converter to Boondocker model 5 years ago; unfortunately, the model I got does not support Lithium, so will need to change that out, when I replace my Trojan 6V's with Lithium sometime this year. Expensive switch, but more usable power and weight reduction...time to bite the bullet in 2024!

If I was staying with wet cell, I would surely consider Walmart, SAM's, or Costco 12V's for cost and convenience...

[AlbertF]

If your battery box can accommodate batteries that are closer to 11" high, you should consider a pair of GC2 (6 volt golf cart batteries) in series. The overall amp hour capacity will be similar, but the batteries may be cheaper and most likely more durable.

I went this route two years ago; I found them on sale at Costco. We're very happy with the setup, and we camp without hookups more than 50% of the time. We use a portable solar panel much of the time. Between the batteries, the solar panel, and the size of the grey water tank, we're good for up to four nights at a time.

We may go to lithium batteries next time, but those would need to drop significantly in cost to make the conversion worthwhile.

[Bill M.]

"Sorry Bill..don’t know where you got that..perhaps from advertising)"

No, not from advertising. I did a lot of reading to find out why the Walmart batteries seemed lacking in expected power and priced so well. Walmart over rates their battery in their website description. Walmart shows the battery life at a 1 amp discharge rate rather than a 5 amp rate that is more or less the "standard" for deep discharge batteries. I finally found a sticker on one of my Walmart batteries (I have used a lot of them for 2 RV's and a pontoon boat) that stated the rating was at 1 amp discharge rate.

The best information on the internet seems to be that if Walmart deep discharge batteries were rated at the 5 amp rate they would be about 67 amp hour batteries. Compared to the 100 amp hour at 5 amp rate from the large AGM from Batteries and Bulbs.

I am not making suggestions or judgements here. Just trying to present facts. I just put 2 of the Walmart deep discharge batteries in my stationary trailer because they are fairly cheap and readily available. And light enough for me to handle., But the trailer that travels benefited from the true 100 amp hour AGM's. 30 amp hours more gives me another night on CPAP and more leeway as to just when to start the generator. The AGM's might resist damage from drawing below 1/2 charge a few times also.

The advertising from many battery companies is probably technically correct but is very deliberately selected and presented to be confusing at best. Without them stating the discharge rate I think Walmart is nearly lying. Maybe that is why they sometimes put a little red peel off stick on the battery that states the 1 hr rate.

[Turkeybaster]

Taylor, our Airstream use is very similar to yours: we seldom boondock, Harvest Host here and there, majority of our camping is with hook-ups. Last year I chose to stay with lead acid batteries when it was time to buy new ones because it works for us for now. Probably go to lithium setup someday but we’re not there yet.
TB

[Boxite]

Not looking for an argument…but I wonder if you could provide some links to the information you gave on WalMart batteries, Bill…

WalMart batteries are made by Johnson Controls… who makes a large portion of batteries marketed under various brand names…and the only data I’ve been able to find is not “weighted” in any way to appear to favor WalMart. The industry standard ratings seem to apply in every case, and I believe Walmart only repeats what Johnson Ctrls publishes.
Thanks.

[Bill M.]

Naaah. I am done with it. I am pretty sure what I said is factually correct. . It has been about 5 years since I did the reading and cared about batteries. I was sitting in a none electric site in Jackson Hole trying to figure out why my batteries were dying. Probably other companies use the 1 amp hour rating also. I think Interstate does not use the 5 amp rate either. When I was looking for ratings Interstate had something I did not understand on the website. All I am pretty sure of is that a Walmart deep discharge battery is substantially less than the 100 amp hours a battery rated at the 5 amp rating is. Even though Walmart says 100 amp hours. Use what you want. Believe what you want. They do not pass out this information without some digging. This may be one reason the conversion to 2 six volt golf cart batteries has been so popular in the past. You are actually getting the rated capacity with the golf cart batteries. But not with the 12 volt lead-acid they replaced. You have to look pretty hard for the information and you have to understand that the capacity rated at the 1 amp discharge comes out a lot higher than the same battery rated at the 5 amp hour rate. The last batteries I purchased for my golf cart were rated at the 5 amp discharge rate. The way I found the 1 amp rate at Walmart was a sticker on one of the batteries.

Look at the Batteries Plus website and check the specifications. Batteries Plus rates their deep discharge batteries at the 5 amp hour rate so it is a good comparison between the batteries. A group 24 flooded cell is 75 Amp hours and a group 31 is 105. That is probably typical of most batteries on the market.

[Hermes]

Comparing LA batteries with AGM batteries with Lithium, is like comparing cars with trucks with tractors, etc. Not all cars or not all trucks are built the same.

My LA batteries (4) have been in my trailer for 5 years (all year round, maintained by my solar MPPT controller) and I did a gravity test on the cells last Fall and they are still like new.

I never use the trailer's converter to charge my batteries unless I have to, since it will overcharge the batteries.

It's the solar system that maintains them with multi-stage, temperature adjusted charge profiles specified by the battery manufacturer.

The batteries that I installed are 6V industrial deep cycle batteries (Rolls batteries). The company that makes them supplies batteries for ships, trains, lift trucks, industrial equipement and large scale solar systems, and have been manufacturing them since 1935.

One of the differences with a cheaper consumer LA battery is the thickness of the plates. You won't scrap your batteries because they were discharged. Rolls have good documentation on their site if you want to learn all about batteries.

I run the equalizer process once per year and add demineralized water about once every 2 years (since the converter doesn't overcharge the batteries they don't evaporate).

And a big factor in my decision is that they will never freeze (if they are charged) even in the coldest of Canadian winters. And I don't need to disconnect and pull them out of the trailer in the Winter (and they don't consume their own power to keep themselves from freezing).

And finally, they are not that much more expensive then a quality consumer grade battery.

I chose a system that is simple (I didn't know any better as a first solar DIY project), cost effective and very reliable and we have never run out of power with our monocrystaline solar panels which push power to the batteries even in cloudier days. As Boxite wrote in his post: KISS. A good principle to keep in mind!

[CBWELL]

As I stated earlier, I use the lead acid flooded batteries, and installed a Progressive Dynamics PD9245 converter years ago. It is a 4 stage converter, good for flooded and AGM batteries and very reliable and economical. If plugged in to electric most of the time you can safely leave your batteries unchecked for a couple of months, I have installed these Progressive Dynamic converters in many units for members of our Club with zero issues. If you are not on power, then a solar panel makes good sense to maintain your batteries.

[Boxite]

Well… the WM Everstart 27DC battery in my Airstream is now 8 years old and is serviced by the original model WFCO converter and is still doing fine and we boondock about 25% of the time. It lives on the WFCO plugged-in to shore power while stored. I do ck and service the water annually. It cost me $97 in 2016 and has never let me down. I’ll replace it this year just because I feel I’ve got my money out of it and like to practice preventive mx. I sleep well at night and do not stress about batteries.

[Daquenzer]

Originally Posted by Boxite

Well… the WM Everstart 27DC battery in my Airstream is now 8 years old and is serviced by the original model WFCO converter and is still doing fine and we boondock about 25% of the time. It lives on the WFCO plugged-in to shore power while stored. I do ck and service the water annually. It cost me $97 in 2016 and has never let me down. I’ll replace it this year just because I feel I’ve got my money out of it and like to practice preventive mx. I sleep well at night and do not stress about batteries.

You will definitely pay more than $97 now. Batteries have really climbed in prices.

By the way…just an installation tip. My cables didn’t fit the new batteries I put in. So not quite a drop and install. Had to get one cable ground out a bit.