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Daveh

Flooded Cell Vs AGM

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I have been researching this issue and going back and forth. I don't mind venting, maintenance or keeping the upright position with flooded cells but I am somewhat torn on the issue of the apparent advantage AGM's have in recharging rate and whether that benefit justifies the cost. I am not going solar at this time but do think there is a strong liklihood that will happen. In the meanwhile I am planning a 500-600 amp battery bank and using the a honda eu2000 to recharge. I would like to minmize generator run time so the quicker recharge of the AGMs appeals to me. Anyway, two questions (1) can someone who has owned both tell me about the real world difference in recharge time between AGM and flooded cell, and (2) is there a significant benefit to AGM if I do move to solar. I know this has been discussed but I am seeing conflicting input and would like to hear some real world experiences. Thanks dave

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Your 2000 Honda should provide enough power to get about 100 amps out of a good charger.

 

If you get an inverter charger that lets you set the size of the power source (sometimes in the owner's manual as breaker size) you can set it to match the Honda so you can pull maximum power while avoiding overloading it. If your other AC and DC loads are low that puts you above what I'd consider safe for flooded batteries. Check the charge rate in the data sheet for the batteries you are considering and see where they fall.

 

I haven't used AGMs myself so I can't give you a comparison but the data sheets do show that bulk charging can go much faster with AGMs, I'm not sure about the acceptance stage but with solar you'd let the panels handle that anyway. Without solar you'll likely do bulk charging two days out of three and on the third day let the batteries charge to the acceptance cutoff point to reduce sulphation and keep the cells in balance. How long that takes on each type I don't know.

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I don't mind venting, maintenance or keeping the upright position with flooded cells

 

I think you answered your own question, Dave. I've run both and know many folks that have. Performance to performance AGM's do NOT justify the additional cost. Not by a long shot. Short and sweet enough? :D They DO have their place in specialized applications.. especially in solar applications where intense sun is limited and folks rely on every amp hour they can produce. With a gen set.. you'll be saving maybe a 1/2 a cap full. It would take a LOT of cap full's to justify the initial outlay for AGM's.

 

From my experience at least, it seems most folks that make the AGM jump have specialized needs. For me, it was weight issues for the size of battery bank I wanted, location for my power center (inside the coach), efficiency between all of my power sub systems, etc... A slight increase in performance in my intended application was just "gravy"... not a major consideration in going to the additional expense.

 

Of course.. some folks I know went AGM because they are so much easier to maintain. If you consider "killing" full sets of wet-cells every season vs the cost of AGM's.. then they are still ahead. But NOT a selling point I would make.. LOL

 

Bottom line.. if you know how to take care of your wet-cells and can get their full life out of them... don't fix what ain't broke. Keep in perspective too that many folks that talk about how short lived wet-cells are... it's not the batteries fault. :P

Edited by Yarome

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Of course.. some folks I know went AGM because they are so much easier to maintain.

That is exactly why I have AGMs. I wanted batteries to use, not be be a job to maintain.

 

Also, because of the packaging, I could stuff 4 Golf cart AGMs is the space of two 12 volt batteries.

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In a GC-2 AGM's will cost you from $90 to over $200 more per battery. You just have to ask yourself if the convenience and features are worth it.

 

BTW if you are using your converter to charge your batteries check it's charging rate, as most top out around 60 amps, though larger ones are available.

 

Chip

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Also, because of the packaging, I could stuff 4 Golf cart AGMs is the space of two 12 volt batteries.

 

Very true! One little gal I know has 4 - 6v agm's stacked on their sides inside her kitchen pantry in one of those camper vans. :P

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In my opinion AGM batteries are over rated for RV applications and the cost is very hard to justify. However, if you storing item's in the same compartment as the batteries then you need AGM. If you are inclined not to want to do maintenance then you want AGM's. However, I have not been able to verify that AGM's will last longer or charge any faster. There are a lot of claims made by the various manufactures. I replaced my engine and house batteries recently and the OEM flooded batteries were over 7 years old. I found the AGM 6 volt had a 200ah rating compared to flooded 230ah of the same size and the cost was close to double. I have a residential refrigerator so I wanted a maximum size house battery bank. AGM vs Flooded is an issue which has pro's and con's and must be tailored to the individual and use.

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The cost is not hard to justify is you are getting old, have arthritis in both your hands and your knees. Yes, you can get down (with kneepads) and check the cells/fill when necessary, wipe, etc., but boy does that take the joy out RVing for that day. So if you can afford it, why not?

 

Barb

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I have 3 Deka AGM's and prefer them for the ease of maintenance, I charge them with solar and use my Honda 2k when needed which isn't to often since I changed out to all LED lights. As for expense my neighbor gets a deep discount through Hensley battery so the cost justification in my case is well worth it. We don't use as much power as those that full time so that probably helps also. I've never had my camper plugged in or hooked up I have no idea what that would be like, Colorado Mtns / national forest is about the only place we ever go. Never need AC but we do seasonally use our share of LP.

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The cost is not hard to justify is you are getting old, have arthritis in both your hands and your knees. Yes, you can get down (with kneepads) and check the cells/fill when necessary, wipe, etc., but boy does that take the joy out RVing for that day. So if you can afford it, why not?

 

Barb

 

Exactly ^ .

 

We have an AGM for our coach battery . I installed that four (ish) years ago and haven't touched it since and no indication that I'll have to anytime soon .

We don't boondock , but for a couple nights a year .

 

I'll use AGM batteries as long as and anywhere I can . We have two sealed wet cell batteries , one in the Jeep and the other for the coach motor , that keep holding on .

Both the XT and the FA50 have AGM batteries . I sold my CB750C that had an AGM battery in it for the 7 years that I owned it and was still doing fine at sale .

 

I guess you know which batteries I prefer . ;)

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We have 300 watts of solar panels on the roof of our RV, and went with Lifeline AGMs when the system was installed 12 years ago. We put them in and forgot about them. Never had to do so much as 1 minute of maintenance.

 

After 12 years they finally wouldn't hold a full charge anymore. But during those 12 years we lived fulltime for 6 years, so they were used every day. When the time came to replace them, we chose Lifeline AGMs again. It was a no-brainer. Bought them online from a California company, who shipped them free all the way across the country!

 

Personally, given our great experience with AGMs (and especially with Lifeline brand), you couldn't pay me to go back to the regular kind. Totally dependable and totally worry-free! (Can't say that about too many things in the RV world).

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AGMs outperform typical flooded cell batteries in every performance category. It is just the way it is.

 

Now, if a specific performance category is not used by you, then it is not a benefit. For example, an AGM WILL take more charge than a flooded cell. Period. It is real and it is true. BUT if you don't have a charger that can do it, OR (more likely) you do not deplete your batteries overnight low enough to have your powerful charger in bulk charge for very long - then you don't get the benefit of that performance category. That is why many people find that AGMs are not of "that much benefit". Because they simply do not need the attributes. For the most part.

 

IF you don't mind, or if you like, fiddling with your battery bank as a "hobby" then you will not be a good candidate for an AGM bank. Because they are truly "set and forget".

 

IF you are typically a price shopper - always looking for the best bargain and gloating that you spent less than your neighbor - they you are not a good candidate for AGMs.

 

And, importantly, IF you are a beginner with batteries, do not have state of the art charging equipment, and don't really understand much about battery management - then you are not a good candidate for AGMs. Mainly because you are statistically more likely to damage your batteries.

 

And, BTW, you can make a pretty good case these days that an LFP bank is a competitive (or superior) cost/performance to a flooded cell bank. Based on initial cost, number of cycles, and size/weight. Now if you want to spend money you might want to look there as well as looking at the AGMs...because in some cases the initial cost is about the same. And lifetime cost is less.

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Just curious, what sort of price comparison are we looking at? I'm thinking of a cost balanced against not only the storage capacity but also the lifetime of the batteries. A cost/year sort of comparison for the equivalent in storage capacity in either type?

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Kirk, ever since Jack posted earlier today I have been reseaching lithiums. So I have gone from Costco golf cart batteries to a $3,000.00 for 400 ah of lithium battery option. Some things are hard to value as in the inherent risk of the relatively new and developing lithium technology and on the other hand the value of significant weight reduction and other benefits of lithium. But on a pure cost basis the best article I have seen is http://www.technomadia.com/2011/11/lithium-update-3-lithium-battery-cost/. Lithiums need time and usage to become cost effective. We have decided on a two year trial period of fulltiming so unless we decide to continue we would never see the expected cost benefit. Just more to think about. I sure love their reduced weight, quick charge and ability to discharge to 80% though. I am figuring 400 amp of lithium would be equivalent to about 650 amp hr of AGM.

Edited by Daveh

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"I am figuring 400 amp of lithium would be equivalent to about 650 amp hr of AGM." That is about right since they can be used to 80% or 320AH of 400AH, and AGM (or wet cells) can be use to 50% or 325AH of 650AH.

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Kirk, ever since Jack posted earlier today I have been reseaching lithiums. So I have gone from Costco golf cart batteries to a $3,000.00 for 400 ah of lithium battery option. Some things are hard to value as in the inherent risk of the relatively new and developing lithium technology and on the other hand the value of significant weight reduction and other benefits of lithium. But on a pure cost basis the best article I have seen is http://www.technomadia.com/2011/11/lithium-update-3-lithium-battery-cost/. Lithiums need time and usage to become cost effective. We have decided on a two year trial period of fulltiming so unless we decide to continue we would never see the expected cost benefit. Just more to think about. I sure love their reduced weight, quick charge and ability to discharge to 80% though. I am figuring 400 amp of lithium would be equivalent to about 650 amp hr of AGM.

Yes, but Technomania's linked chart doesn't compare Lithiums and AGMs to flooded GC-2s or flooded S-550 Rolls/Surettes.

 

Here's a more comprehensive chart:

 

Lithiums (using their numbers) $3,100 140lbs usable ah 400 Cycles 2,000 cost/cycle $1.55 Cost/cycle/amp hour .003875

AGM's (using their numbers) $1,840 535lbs usable ah 400 Cycles 500 cost/cycle $3.68 Cost/cycle/amp hour .00736

GC-2s (priced at my Sams) $704 528lbs usable ah 400 Cycles 500 cost/cycle $1.41 Cost/cycle/amp hour .00282

S-550s (4- priced at Whsle Solar) $1360 492lbs usable ah 428 Cycles 1,400 (at 50% discharge) cost/cycle $0.97 Cost/cycle/amp hour .00227

S-550s (4- priced at Whsle Solar) $1360 492lbs usable ah 599 Cycles 1,000 (at 70% discharge) cost/cycle $1.36 Cost/cycle/amp hour .00227

Note: If only 300 usable ah are needed, 2 S-550 Rolls/Surrettes will only weigh 246 lbs. and cost 59% of lithiums and only 30% of the cost of AGMs on a cost/ah basis, if you can spare the extra 100lbs of weight vs. the lithium. There may be a volume and a maintenance penalty for flooded lead acids but there I no weight penalty vs. AGMs. So if you can afford to pay the difference for the convenience, go for it. I'd rather have 3 times the battery capacity for the same dollar spent.

 

There's no right or wrong answer, as in many decisions in life. If you can spare the weight difference, strictly from an economic sense, the flooded lead acids are the best value long term, especially the Rolls/Surrettes.

Here's the link to where I got my data from the S-550s http://www.wholesalesolar.com/products.folder/battery-folder/rolls-s550.html and here; http://pdf.wholesalesolar.com/battery-folder/surrette/S-550.pdf

 

Chip

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We had three 8D LIfeline AGM batteries in our bus conversion. The company supplied them to us and told me to abuse the hell out of them, to run them down as far as I wanted and charge them back up, and basically to try to destroy them. We routinely ran them down to 11.5 and even as far as 11.3 a few times and after over 8 years they were still gong strong when we sold the bus. I'm a fan of AGMs and will be replacing the wet cell batteries in our present coach with them. We don't have solar and don't dry camp much any more, but my arthritis makes dealing with wet cell batteries too hard these days. For me, they are worth the investment.

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For those unable to get around like the used to, this is an option that makes watering flooded batteries as painless as possible: https://www.flow-rite.com/battery-watering/pro-fill

 

Once installed there's no need to remove caps, check the water level, etc. Just squeeze a rubber bulb a couple times once a month and you're done. Here's a brief video: https://www.youtube.com/watch?v=zKrIdYhV9Ak

 

Chip

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Seem to be on the same wavelength with Sushidog, Bill Joyce, and DaveH concerning LFP. The salient points for us in purchasing an LFP battery bank were: cube, weight, and no Peukert effect. They have provided us with solar autonomous boondocking for the last 18 months. The 500 pound difference between LFP and equivalent lead acid for 9.6 kW-hrs would have put us close to the pin weight and frame limitations of our 5th wheel (where do you put 750 to 800# of batteries). Large motor homes can carry one heck of a lot more weight and weight and cube are probably of much less importance but it is to be noted that Liberty Coaches ($1.8M and up) claim 800 to 1000# less weight in the Liberty Ladies equipped with LFP.

 

They are undoubtedly not cost effective if you do not do a lot of boondocking.

Reed and Elaine

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12.5 x 7.125 x 16.75 are the dimensions of a S-550 Rolls/Surettes. A 6 volt Lifeline 4CT golf cart is 10.28 x 7.06 x 9.92. Normal battery compartments can hold the golf carts, only a few can hold the S-550.

Edited by Bill Joyce

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Only one additional comment to add. ....

 

Most people do not cycle their wet cell or AGM batteries as deep as the comparison charts indicate. It does have an impact on them. The charts are correct in their comparisons, as far as I can tell, but not in how people "typically" use the battery bank. With LFP batteries - because they are new to people and they are being "trained" fresh - people do tend to cycle them heavily. And the LFP does not really care about it....while the others do to a greater extent. That is a factor in "livability" per stored Ah. IMO.

 

I have the weight carrying capacity in my 5th wheels. I do have 6xL16 now....and they are NOT light. But the LFP has some characteristics that are pretty sweet. And are priced around the same. To me the jury is still out - but it looks like their time may of come (finally).

 

Another good source of comparison is on the starlight solar website.

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Good information on Starlight Solar's LFP battery banks designed for solar applications. AM-Solar's site says that they also are thinking of installing LFP in the near future. The problem with current LFP battery pack systems, as noted in a posting above, is that they are designed for electric vehicles. This does not affect the basic battery pack but the BMS and monitors are set for very high C rates. I don't think this has much of an effect.

 

Didn't know that Balqon was in financial trouble. Their prices seemed reasonable. Their 9.6 kW-hour package weighs the same as our 4 x 2.6 kW-hr batteriy bank (180 amp-hours at 13.5 V nominal each), around 250#. Placing four batteries around the forward bay was a lot simpler than trying to emplace a 250# behemoth.This also meant that the four batteries could be placed where they had the most support from the frame. The floor of the bay is designed to hold an Onan 6.5 kW propane generator (290#). The batteries are in series for a 48 V nominal (54.4 V actual) bank. Higher voltage meant using smaller cabling (90 V from the panels) and a smaller TriStar MPPT controller. We have had a maximum of 1330 W to controller (15 amps at 90 V as opposed to 110 amps at 12 V) and the battery bank at 54 V means only 24 amps so that an MPPT-45 is quite sufficient.

 

Reed and Elaine

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Just a point of information. AM Solar is already installing lithium technology. Have been for a little while now. In fact, I think Bill has a bank from AM.

 

John Palmer and I have been having some interesting conversations on the topic as well. He may do it in the future. But does not currently.

 

I think the technology (and the prices) have changed since the Technomadia folks put their system in some years ago. I don't know if Chris has updated their site on that topic since that time, though.

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One troubling thing I saw on Technomadia and then saw on other sites when researching LFP's was a 15% drop in capacity with LFP's after the first year. I have not read anywhere that tthe drop continued after the first year and the reviews were essentially raves despite the loss since they have no sag etc. They recommmend taht if you are not using them they should be stored at about 50% charge to avoid the loss in capacity but I would think Technomadia had them under constant use and they still experienced the loss. There also seems to be a lot of talk about balancing the cells, which just may just be becuase I am reading posts by early adopting battery geeks, but it seems they put in a lot of effort to monitor these batteries

 

Also, since I am still planning my system. I am wondering whether going to LFP would have implications for my other equipment selections. Currently, the only thing I have actually purchased is the Magnum 3012 hybrid inverter. My other anticipated purchases have been heavily influenced by Jack's blog and this board. But, for instance, Bill Joyce. when you got the Elite Solution batteries. I assume you also got their battery managment system. Is this redundant with something like the Bogart system I was contemplating purchasing or do you run both?

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Also Reed, the gist of what I got yesterday when researching was that Balqon is bnakrupt but they were a distributer for, or had some relationship. with Winston which is still selling batteries.

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