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 (http://www.vonwentzel.net/Battery/01.Type/index.html)
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.
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/7175MK%20Gel%20Brochure%2011-09.pdf) http://www.mkbattery.com/documents/3701MK_AGM_LG_v3_r8.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.
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
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
Deep Cycle Batteries for RVs (http://www.amsolar.com/home/amr/page_21)
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
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
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 (http://www.solar-electric.com/decybafaq1.html#Gelled) 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 (http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf)
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
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
My understanding is that the Gel are less forgiving than the AGM. So in my world the AGM would be my choice.
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.
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
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
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. ;D
Dave M
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
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
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 (http://www.amsolar.com)
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?
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.
Might I suggest searching the forum as well? There have been some great discussions in the past :)
Michelle
My electrical buddy with 25 years Rv experience uses MK gels for house and Agm for engine start.
Bob
(https://www.foreforums.com/imagecache.php?image=http%3A%2F%2Fwww.civicsolar.com%2Fsites%2Fdefault%2Ffiles%2F432x249xvonwentzel.GIF.pagespeed.ic.F42YTRR2Zg.png&hash=2f86d059aba3c3be117e30392f565f37" rel="cached" data-hash="2f86d059aba3c3be117e30392f565f37" data-warn="External image, click here to view original" data-url="http://www.civicsolar.com/sites/default/files/432x249xvonwentzel.GIF.pagespeed.ic.F42YTRR2Zg.png)
http://www.civicsolar.com/sites/default/files/432x249xvonwentzel.GIF.pagespeed.ic.F42YTRR2Zg.png (http://www.civicsolar.com/sites/default/files/432x249xvonwentzel.GIF.pagespeed.ic.F42YTRR2Zg.png)
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.
I understand that the AGM is less subject to vibration damage?
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 (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.
Ok so here is a big one. How many batteries and how many years would it take to use this type battery Vs Standard AGM or Gel
$3499.00
12V 300AH Lithium Ion Battery
Size: 8D
Nominal Voltage: 12.8V
Amp Hours: 300
3000 Cranking Amps
Length (inches): 20.47"
Width (inches): 10.5"
Height (inches): 9.0"
Weight: 93 lbs.
360 min @ 50A
900 min @ 20A
Max Continuous Discharge 100A
Charge Voltage: 14.6v
Life in Cycles: 3000-5000
12v 300ah lithium ion battery (http://www.lithiumion-batteries.com/products/12v-300ah-lithium-ion-battery/12v-300ah-lithium-ion-battery.php)
There have been several threads on LiFePO4 batteries in the past year or so. Here are a couple I came up with doing a quick search for lithium batteries on the forum. Besides the cost of the batteries, one needs to factor in an inverter/charger that is compatible.
Lithium Iron Phosphate batteries (http://www.foreforums.com/index.php?topic=13576.0)
Lithium Iron Phosphate Batteries (was House Battery Replacement) (http://www.foreforums.com/index.php?topic=15494.0)
Michelle,
For Sure.. one day they will be standard equipment and weigh about 40# less.
Not to mention significant fire risk
I was told the Agm batteries cannot be equalized like the MK gels.
My buddy that does electronics and batteries in big stuff only for 11 years mentioned better life by annually disconnecting the gels and equalizing them individually.
Some last 4-5 years and he has some at ten years.
As a dry camper that I do a lot of the gels were better as was my absorbtion refer in his opinion.
Was not a lifeline fan.
Li ion phospate is what I almost bought instead. Other than the $5k plus price range.
Liberty uses two if memory serves me. Its only money.
Bob
Yup, Liberty uses Li ion you are right.
I think you may find Bob that the gels cannot be equalized if I have it right. The AGMs can up to around 15v as I have mine set every 28 days to equalize at 14.7 v (for a short period) just to make sure they are fully charged and this was as told to me by Lifeline themselves, and AMSOLAR set it that way and their business is solar and battery care.
I stand to be corrected.
John H
Here is my experience with AGM vs Gel.
I have an 11 year old 8D Gel which still has a measured capacity of more than 160 amphours (new was 220 amphours). I connected it at the start battery bank cables of my M11. It cranked fast for 1 sec, bogged for half second, then cranked steady (not real fast) but the M11 started. Rating is 1150 CCA.
I have two Lifeline (made by Concorde) 8D AGM batteries which are three years old.
I connected one AGM at the start battery bank cables of my M11. It cranked fast for 1 sec, then bogged, no more cranking - did not start the M11. Two AGM batteries together cranked faster then one Gel and started the M11. Rating is 1450 CCA.
I do not know why one 1150 CCA Gel starts my M11 but one 1450 CCA AGM does not!
Point 1:
I did discover that the AGM batteries were not fully charged (at 95%) after installing amphour meters on each battery rather than just one for the bank. AGM batteries are now fully charged.
Point 2:
The Gel had a desulfator on it (which I built years ago) for months, but AGM batteries did not (they do now, bought off eBay). I plan to do this testing again and guess that the significant factor is the use of desulfators, rather then not fully charged.
Note:
Desulfators take months to do the same thing as equalization does in a few hours, but is easier on batteries and batteries are always desulfated.
When I bought the Lifeline AGM 8D batteries in May 2010, I was unable to find a source for Gel 8D batteries that was not 50% more expensive than Lifeline AGM 8D batteries. My first choice was Gel but money talks.
I believe that the suppliers of sealed batteries are reluctant to sell Gel batteries because they are much more vulnerable to misuse than AGM batteries are. I believe that statistics from a battery supplier would reveal much higher % of warrantee claims with Gel batteries than with AGM. If I were a dealer, I would promote and sell AGM batteries.
I also believe that the Gel is the cycle king if managed properly but that the lifetime cost per cycle is about the same (unless the Gel can be purchased at the same price as an AGM).
I have noticed that when solar charging my batteries, the Gel battery is still being trickle charged for almost two hours after the AGM batteries are fully charged. I have reset the charge point to 14.6 volts on the solar controller which is recommended for AGM but too high for Gel. I believe 14.6 is fine for Gel from a solar system because the amperage is limited by the solar supply (not the battery) and therefore not harmful to the Gel. From an alternator (mine is set at 14.4v) or high capacity battery charger, 14.6v would damage the Gel because of the high current.
Based on my experience with faster solar recharge, when my Gel battery is no longer serviceable, I will replace with AGM.
Another interesting observation is that when checking in the morning, the Gel has provided 50-100% more amphours than either AGM battery and when solar charging, the amps into the Gel is 50-100% higher than amps into either AGM battery. I believe that this is due to the lower internal resistance of the Gel, in spite of what manufacturers claim.
I have a question regarding use of a desulfator on the house batteries. My bank of 3 gel batteries is now 10 years old. It has been a couple of years since I determined they were still holding a good charge, and use tells me they are still in good shape.
Now to the question....I attached a single desulfator to the outermost battery a couple of years ago. Are the other two batteries getting sufficient benefit or should I consider moving it to the center, moving it periodically, or adding two more? Also, would the starting batteries get any of the goodness with the boost switch on, or is the cable length too long?
I will put my 2 cents out here about what I was told by the manufacturers of a desulfator. They recommend 1 for each battery but you can use one across all 3. As they connect to the + - of each battery posts it seemed to me to be more prudent and make the unit work better if I got 3 so I did. They are the same as Wyatt now uses (wizbang) and mine have been on about 3 months so hopefully are now doing their job. There is a lot of talk from different sides as to whether they do anything, but I am willing to give it a try. The principle is obviously correct and I hope to get the benefit of them and make my batteries give good service and life. Hope it works.
John H
When my guy mentioned equalizing the MK gels I did not question him as he was on a roll.
Was delivering a fifth wheel with three MK gels in plastic boxes and a large magnum inverter to run ducted roof air without a gen over a weekend. Evening use dry camp noise compliant use.
Will write down his explanation but he designed the electrical systems for vogue motorhomes in 1985 and only does 45's and busses for the last twenty years.
Maybe the mk's can take things differently. Never thought about it. Will ask.
My installation is currently one new MK and two used ones.
He said the two used ones tested 1100 cca's with a new rating of 1150. But he said new mk's consistently tested at 1300-1400 cca's. my used came out of a 24 volt bus. Two of the four typically die he said and as he would only replace all four for a prevost I thought I would see how the combo holds up. I know it wrong but and easy fix later. He redid the cabling to have the positive from one end battery in the system and the negative from the other end of the string. And added my desulfinator to the same ends so its slowly working on all three batteries.
He mentioned 16 volts to the mk's annually individually to equalize them. And he has ten year old sets equalized annually. not sure how long but bill does this stuff all day.
Found every electrical issue in my 16 year old coach and fixed them for minimum hours.
Old bud. We used to be the bluebird guys for the so cal dealer in 1990. Roof air ran of of batteries in a bird in those days. Need one of their dual plug in cord setup. 30 and twenty amp box then fifty to the coach.
Bob, if you read all the different articles out there you may find that a lot of the things you mention are the exact opposite of what you mention he said was ok!!!!
I am not an electrical expert in any way, but did judt read an article on MKs that said do not charge over 14.1 volts ???
I would not mix new and older ones- but sometimes we have to do it.
read some of the Battery articles on Beamalarm to see what I am saying.
John H
14.1 volts is rated max charge voltage at about 65 degrees with higher voltage at colder battery and lower voltage with warmer battery. So a temp compensated charger is very important to use.
Desulfators:
The desulfators I use are considered passive because they draw about 60 milliamps from the battery and send a 50 volt, 6amp spike back into the battery. Because they are passive they are not very powerful by design, to limit the draw from the battery, such that a lead wire of even 12 inches will considerably reduce the amount of spike energy that reaches the plates in the battery. The desulfation process with a passive desulfator requires a day per amphour with short leads. Our 8D batteries take at least 6 months to be desulfated with short leads. With long leads desulfation will take much longer. Definitely use a desulfator for each battery with leads as short as possible. I attached mine with 3M tape to the battery case.
In my case there is 6 feet of battery cable plus two amp shunts between the negative posts of the two AGM batteries behind the rear tires. I installed the amp shunts inside under the foot of the bed rather than outside behind the rear tires.
After I built a desulfator (circa 2005), I attached it to a start battery which would not start my car and would not take a charge. I checked the voltage of the battery many times during the next week and was surprised that the voltage was getting higher each day for the first 5 days, even though the desulfator was drawing 65 milliamps and there was no battery charger being used. I attached a trickle charger at that point and left it for a couple months. Battery would then start the car and take a charge.
The stabilized voltage (disconnected for 10 or more hours) of a fully charged battery will vary with the type of battery and the state of health of the battery. A healthy fully charged flooded battery will have a stabilized voltage of 12.75v, an AGM battery will be 12.80v, a Gel 12.85v. Desulfation will raise that stabilized voltage. My 11 year old Gel which has been desulfated for years has a stabilized voltage of over 13 volts.
If you are curious, check the stabilized voltage of each house battery before desulfating and check it again after a year of desulfating. I would be most interested in what each of you discovers.