AGM batteries vs. gel batteries

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AGM batteries vs. gel batteries

November 05, 2012, 04:05:16 pm

Michael, in regards to the battery set up... I been researching this subject myself, our coach has two 6 year old usable MK (Deka) AGM 8A8D batteries which hold a charge just fine, but I'm looking to go solar and maximize boondocking capacities. So I have been doing a bit of research, and regards the AGM versus gel cell type batteries it seems that the AGMs should be longer-lasting from what I've been able to glean. Here is a link which has a comparison chart;
Battery Types: Flooded versus AGM and Gel
According to the chart at that link at least, AGMs have higher energy density, can recarge faster, and about double the charge cycles as long as they are appropriately charged and not drained down to below 50% or so. I am certainly not an expert, though many years ago I worked as a technician in the aviation battery locker on an aircraft carrier, but I am hoping that lithium iron phosphate battery technology (LiFePO4) will be cheap enough by the time our's age out to replace the AGM's. The current price on the lithium style batteries is about $3000 give or take to replace the capacity that would equal the ones we have already. The advantage would be that the lithium batteries would be less than half the weight and have a theoretically much longer life. The other advantage is that the amp hours can be about half and still provide the same usable capacity as the current AGM/Gell style batteries because they can go much deeper into their discharge cycle without being damaged. While the cost premium of the lithium batteries is significant, so are the potential weight savings depending on your application... And or ability to lift the heavy son of a guns in and out of where they live.

Re: AGM batteries vs. gel batteries

Reply #1 – November 05, 2012, 05:46:45 pm

Quote from: acousticart – November 05, 2012, 04:05:16 pm

So I have been doing a bit of research, and regards the AGM versus gel cell type batteries it seems that the AGMs should be longer-lasting from what I've been able to glean.

Don,

Not trying to start an argument, but according to MK Battery brochures, the life cycle chart is 1000 50% charge and discharge cycles for gel and 500 for AGM. Could be different for other brands. http://www.mkbattery.com/documents/7175MK%20Gel%20Brochure%2011-09.pdf http://www.mkbattery.com/documents/3701MK_AGM_LG_v3_r8.pdf Charts are on the last page of each brochure and best to use separate windows to compare. I could not find any proof that AGM's are better than Gel's for cold weather, so I may be wrong about that.

Re: AGM batteries vs. gel batteries

Reply #2 – November 05, 2012, 06:24:00 pm

No argument here Jerry! Just a quest for knowledge and an illustration of why one needs to source information from multiple places before laying out hard earned money... I haven't really been in the market for buying new batteries yet sice our have life in them (not to mention my real priority is to get the coach back on the road!), more just thinking about upgrades down the road, so my research focus has been on the inverter and solar panel type upgrades. But according to the MK website you are correct. They make both and they state what you said... The AGM's will take a charge faster and output higher currents, but the GELS apparently outlast them. As it turns out, I was mistaken about our batteries... I just looked at them and they say MK Gel right on them, but the space on the label where the type is supposed to be stamped is blank or has faded away. I assumed they were AGM's because that is what the dealer said that we bought the coach from. Looking at the brochure that is linked on Barry B's site, our coach came with 8D Gels and is apparently what the PO replaced them with. One way to tell what type of MK battery one has may be as simple as the color of the top. Black for AGM and Grey for Gel... at least judging by the picture on the MK brochures. Ours have grey tops... thanks for the links!
Don

Quote from: Jerry Whiteaker – November 05, 2012, 05:46:45 pm

Don,

Not trying to start an argument, but according to MK Battery brochures, the life cycle chart is 1000 50% charge and discharge cycles for gel and 500 for AGM. Could be different for other brands. http://www.mkbattery.com/documents/7175MK%20Gel%20Brochure%2011-09.pdf http://www.mkbattery.com/documents/3701MK_AGM_LG_v3_r8.pdf Charts are on the last page of each brochure and best to use separate windows to compare. I could not find any proof that AGM's are better than Gel's for cold weather, so I may be wrong about that.

Re: AGM batteries vs. gel batteries

Reply #3 – November 05, 2012, 07:09:47 pm

As regards pricing, I found the receipts for our MK Gel batteries. It does say "2 8G8D batteries @12v-225AH". MK 8A8D AGM's are 245AH... They were purchased in May of 2007 from Anaheim Coach and Trailer Co. for $329.50 apiece. Not sure if that bears any relation to reality in 2012, but was a good price at the time...
Don

Re: AGM batteries vs. gel batteries

Reply #4 – November 05, 2012, 07:11:26 pm

Deep Cycle Batteries for RVs
Just to add more info into the equation you WILL find that the solar people all say AGM are the best. I spent many months talking to just about all the main players in the battery world (germany and china included) and all the techs said go AGM. So I did. I got mine 14 months ago from AMSOLAR for 500 each and now they are 700. Greg(amsolar) is a well known expert on anything solar and the link at top shows they use AGM. Arizona wind and solar if I am correct also say AGM amd they are a biggy in this field. Lifeline AGM are 255 amp at 20 hrs
FWIW
John H

Re: AGM batteries vs. gel batteries

Reply #5 – November 05, 2012, 07:26:50 pm

Not wanting to derail the thread, but I think batteries are a topic near and dear to many of us here... John, I have admired your solar setup from afar since I know you frequent Mexico and other out of the way places... when I grow up, I want to be just like you! Seriously though, do you know what the characteristics of AGM's are that make them better in solar applications? Is it that they make better use of charge energy? That is one of the things on the page of the link I posted earlier in this thread. If so, that would indeed tip the balance in their favor to get the most out of the available suns energy... depending on the wattage and number of solar panels you have on top. I am wondering though, if you have enough solar capacity to max out the charging rate, if perhaps the longer life cycle of the Gels might tip the balance in their favor...
Don

Quote from: John Haygarth – November 05, 2012, 07:11:26 pm

Deep Cycle Batteries for RVs
Just to add more info into the equation you WILL find that the solar people all say AGM are the best. I spent many months talking to just about all the main players in the battery world (germany and china included) and all the techs said go AGM. So I did. I got mine 14 months ago from AMSOLAR for 500 each and now they are 700. Greg(amsolar) is a well known expert on anything solar and the link at top shows they use AGM. Arizona wind and solar if I am correct also say AGM amd they are a biggy in this field. Lifeline AGM are 255 amp at 20 hrs
FWIW
John H

Re: AGM batteries vs. gel batteries

Reply #6 – November 05, 2012, 07:44:17 pm

Don, look at the link to what Greg said and I will ask him your question and get back to you.
John H

check this one out too it tells you why agm are better.
Deep Cycle Battery FAQ Electrolyte

here are some real tech answers from Concorde (lifeline) see page 11 of the manual at this link
http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

Re: AGM batteries vs. gel batteries

Reply #7 – November 05, 2012, 08:24:37 pm

It is interesting to see the dichotomy between the different sources... The MK brochures seem to clearly give the longevity nod to Gel's. Since they have both horses in the race, you would think they could be trusted to be objective. It gets complicated to try relate the charts to real world use however... all the sites that I have been frequenting in my solar research seem to favor the AGM's, which may be a feature of real world use vs specifications. My jury is still out (hopefully not a hung jury!), but I am hoping to make the leap directly from our Gels to some LiFePO4 batteries... even if I have to build my own packs from cells. That also figures in the choice of inverter/converter charge combos. The new version of Magnum's MS2812 (the MSH2812M) will support load sharing. I believe the current generation already supports a lithium charging profile... Another thing altogether to figure out how to deal with two different types of battery chemistry as regards the chassis batteries. I still have a lot of learning to do!
Don

Quote from: John Haygarth – November 05, 2012, 07:44:17 pm

Don, look at the link to what Greg said and I will ask him your question and get back to you.
John H

check this one out too it tells you why agm are better.
Deep Cycle Battery FAQ Electrolyte

Re: AGM batteries vs. gel batteries

Reply #8 – November 05, 2012, 11:07:46 pm

If I was buying batteries today, after reading a good portion of the Concorde technical manual, I would definitely go with their AGM batteries. It seems pretty telling that they started making Gel batteries an now have dropped them in favor of the AGM style. Quicker to take a charge and not quite as sensitive to charging voltage either...
I am glad that I don't have to make that decision today! I will baby these MK Gel batteries along until we are ready make a switch to the full-Monty solar set up, Then I will find another use for the Gels...
Don

Quote from: John Haygarth – November 05, 2012, 07:44:17 pm

Don, look at the link to what Greg said and I will ask him your question and get back to you.
John H

check this one out too it tells you why agm are better.
Deep Cycle Battery FAQ Electrolyte

here are some real tech answers from Concorde (lifeline) see page 11 of the manual at this link
http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

Re: AGM batteries vs. gel batteries

Reply #9 – November 06, 2012, 07:16:18 am

My understanding is that the Gel are less forgiving than the AGM. So in my world the AGM would be my choice.

Re: AGM batteries vs. gel batteries

Reply #10 – November 06, 2012, 08:13:10 am

I think FT went back to Gels in the coaches. Maybe someone at the factory can ask while they are there.
I looked a while ago at switching to AGM and decided to stay with Gels. I too hope LI comes down enough to use that next time. I know Liberty is putting them in their coaches now.

Re: AGM batteries vs. gel batteries

Reply #11 – November 06, 2012, 08:44:26 am

AGM is great technology in special applications such as aircraft that make loops and no liquid is the best policy. I like them for the start batteries because Forrest has 30 day periods of no use, and these hold a charge just as well as the gels. Gels have the great attribute that the number of life charge cycles is greater than the AGM deep cycle...not to mention price. IMHO

Re: AGM batteries vs. gel batteries

Reply #12 – November 06, 2012, 11:30:51 am

Peter, if you have AGM as start and Gell for house, you have to be aware of the different charging requirements of both (I am sure you are). I think I read in the Concorde manual( or Arizona wind site) that you actually can get as many or more cycles from AGM if you are very carefull on the charging and use of them than gell.(I will go back and look)
I bet FOT went back to Gell mainly due to price as the new coaches have so many batteries they can save a few buck's doing this. Like everything else, they last a few years then the owner has to decide the best course of action for themselves. If you can afford an IH45 what does the cost of new batteries matter in 5 yrs time???
John H

Re: AGM batteries vs. gel batteries

Reply #13 – November 06, 2012, 12:57:34 pm

I enjoy all the hype on the Gel vs AGM batteries. I have for over 25 years purchased batteries from two chaps who were engineers for Delco Battery and left to have their own retail business. When I decided to replace my 8 yrs old Gel set, I asked for their opinion/fact about the Gel vs AGM. In the end I took their advice and bought 3 new 8D Gel replacements, price was not a consideration. One fairly good point, I paid $265 each. Like I said I spend alot of money with these guys and they thank me in some ways.
Ya just gotta do what works best I think.

Dave M

Re: AGM batteries vs. gel batteries

Reply #14 – November 06, 2012, 01:45:18 pm

As far as I can tell, the prices are too close to a wash between AGM and Gel to make any difference... at least with East Penn/Deka MK batteries who makes both. If on the other hand Gels would have more cycles in your application, then not having to replace them as soon makes a significant difference. Conversely, if the AGM's do charge more quickly from the same amount of Solar capacity (or Generator for that matter), then that is a definite plus for them. Man... tough to know! The Concorde docs make a really good case for the AGM's (at least for theirs anyway...) and all the Solar proponents seem to feel that AGM's have the edge... Like I said, I hope I can hold off until a clearly superior choice such as the LiFePo4 comes down to earth in price. Or maybe if I was to sell my first born... $:-\$
Don

Re: AGM batteries vs. gel batteries

Reply #15 – November 06, 2012, 04:55:21 pm

Dave, if all the solar experts say AGM they must know something, and, as you do not have solar then the gell would be fine I guess esp' if they cost that little!! Depends on what you have for start batteries too.
John H

Re: AGM batteries vs. gel batteries

Reply #16 – November 06, 2012, 08:02:00 pm

Don, just got this from greg at AMSOLAR, read them the way you want.

John,

In a nutshell, Gels require a fairly tight charging regimen and are very unforgiving if you exceed it. Considering that there may be multiple charging sources in RVs (engine alternator, solar panels, converter or inverter/charger), it is difficult to meet the exacting requirements of the gel batteries with all the sources. This is not to say that gels are not good batteries. They are just better used where they are only being charged by one source and have a battery box that is kept at a fairly constant temperature. I know of some gel batteries used in off-grid homes meeting the above mentioned requirements that last for a long time and give good service. I just don't recommend them for RV use.

AGMs are kind of in the "sweet" spot between flooded and sealed batteries. They are more forgiving than Gels in the charging requirements and have no maintenance. AGMs are more efficient at accepting a charge and have a slightly lower self-discharge rate. Also, the Lifeline brand of AGMs have a prorated 5 year warranty that they have been honoring with little to no fuss. This isn't always the case with other brands.

Hope that helps,

Greg

J. Greg Holder
President
AM Solar, Inc.
Welcome to AM Solar_Your RV Solar Specialists since 1987

Re: AGM batteries vs. gel batteries

Reply #17 – August 07, 2013, 09:58:40 pm

I understand the differences in the construction and operation of these battery types. I have seen both types used in both chassis and coach applications. But which type is best for coach batteries? For chassis batteries?

Re: AGM batteries vs. gel batteries

Reply #18 – August 07, 2013, 10:02:03 pm

Your questions will likely generate a lot of Ford vs. Chevy type discussion. I went with gels for the coach(same as OEM) after deciding they would last longer than AGM. I use AGM's for the chassis so I don't have to worry about charge voltage.

Re: AGM batteries vs. gel batteries

Reply #19 – August 07, 2013, 10:12:47 pm

Quote from: BamaFan – August 07, 2013, 09:58:40 pm

I understand the differences in the construction and operation of these battery types. I have seen both types used in both chassis and coach applications. But which type is best for coach batteries? For chassis batteries?

Quote from: amos.harrison – August 07, 2013, 10:02:03 pm

Your questions will likely generate a lot of Ford vs. Chevy type discussion.

Might I suggest searching the forum as well? There have been some great discussions in the past

Michelle

Re: AGM batteries vs. gel batteries

Reply #20 – August 08, 2013, 12:10:21 am

Quote from: amos.harrison – August 07, 2013, 10:02:03 pm

Your questions will likely generate a lot of Ford vs. Chevy type discussion. I went with gels for the coach(same as OEM) after deciding they would last longer than AGM. I use AGM's for the chassis so I don't have to worry about charge voltage.

My electrical buddy with 25 years Rv experience uses MK gels for house and Agm for engine start.

Bob

Re: AGM batteries vs. gel batteries

Reply #21 – August 08, 2013, 12:36:25 am

http://www.civicsolar.com/sites/default/files/432x249xvonwentzel.GIF.pagespeed.ic.F42YTRR2Zg.png

Re: AGM batteries vs. gel batteries

Reply #22 – August 08, 2013, 12:47:31 am

Like Brett says...this is a Ford vs Chevy question. It gets asked and discussed over and over, and seldom do I think anyone's mind gets changed. There are datasheets and datasheets...some lead one to believe GEL is the answer, and some lead one to believe AGM is the answer.

Frankly, if I wasn't convinced my unspoken choice was the right one, I'd call Foretravel and do what they suggested.

Re: AGM batteries vs. gel batteries

Reply #23 – August 08, 2013, 01:13:48 am

I understand that the AGM is less subject to vibration damage?

Re: AGM batteries vs. gel batteries

Reply #24 – August 08, 2013, 07:51:12 am

Concorde, one of the major manufacturers of batteries for a wide variety of markets, provides some very interesting documentation available at http://www.lifelinebatteries.com/manual.pdf . After fully digesting the information they provide, it's very difficult for me to believe that AGM is not the best battery technology available for both starting and deep-cycle applications.

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