SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Which AGM batteries are best

9K views 24 replies 14 participants last post by  Maine Sail 
#1 ·
We are replacing our house batteries with AGMs. Are trying to determine which brands are best. Would appreciate experience with different brands.
 
#2 ·
I just found some l16 group batteries for my solar house (AGM). I was told that for the money ($400) per battery, and 380hr/20hr rate, 6v. these were the best, they come out of china and they make batteries for a lot of the marine industry, universal power group is the name of the company, i found them thru: the solar biz.com
 
#3 ·
C&C,

Not trying to second guess you here, but are you sure you want to go with AGMs? They're great batteries, but unless your electrical system is designed to capitalize on their benefits they may not be much of an improvement over flooded cells.
 
#5 ·
Not to mention you can put AGM's anywhere, or on their side, they work great on boats and tight spaces where you won't have to touch them..also they don't "off Gas" which is corrosive and dangerous, less of that stuff on a boat the better in my book.. Gel batteries are to sensitive and people end up frying them, and lets face it lead acid is old technology that is troublesome to maintain and limited in charging rates, AGM's should be the only option on a sailboat..upgrade you charger and you'll take full advantage of AGM's benefits, if not they will charge like a lead acid and still be superior in fitment and reliability and safety.
 
#7 ·
About a year ago I bought 4 Lifeline GPL-27T's for my boat and I've been very happy with them. If I remember correctly, I purchased them from Dixie Battery (in AL) at a good price. They were shipped by UPS to my doorstep.
 
#9 · (Edited)
There are many good AGM batteries out there, if they are treated well. My two favorites are Lifeline and Odyssey. If going AGM on my own boat today, and cost was not an issue, it would likely be Odyssey.

Lifeline's have the huge benefit of being able to be "equalized" or "conditioned" where other AGM's do not. This can be a very important feature.

Deka / East Penn licenses their AGM and GEL technology from Sonnenschein in Germany and builds the batteries here in the US. West Marine and Sam's Club both sell them. Of course at Sam's Club a 6V AGM or group 31 12V are less than half the price of WM.

Many other AGM's are built by companies like Full River in China for big name brands who mark them up and churn them out. If you stick with Deka / East Penn, Lifeline or Odyssey you'll be doing well.

There are drawbacks to AGM however and they ideally need to be installed as a "system" not just as a battery. I see PILES of AGM batteries die well before wet cells and well before they should because people have not taken the time to install them properly or to treat them properly.

Heck just yesterday I quoted a customer on replacements for his four year old Lifeline GPL-4CT 6V's. He has done everything right in terms of alternator, charger etc. etc. EXCEPT he is on a mooring and the batteries rarely if ever get back to 100%. He's killed a $1400.00 bank in four years. I also quoted him on solar panels so this won't happen again.

Today I worked on a boat with a stock 50A alternator, no solar and single stage ferroresonant charger so old it should be a boat anchor. The two 6V batteries are 7 years old, by date code, and just now looking like they perhaps need replacement. He paid about $75.00 each for them. This 7 years despite the owner doing NOTHING to care for them. He never added water and only charged them to full once in the fall and spring.

BTW, AGM, GEL and FLOODED batteries are all LEAD ACID batteries.

Feel free to read this for more on AGM batteries:

AGM Batteries - Making The Choice
 
#10 ·
My last Lifeline AGM series 27's were still going strong at 9 years old. I replaced them only because I was going on an extended cruise and the dealer said they were typically good for 8 years! Lifeline has a large series 31 called 31XT which is basically half of an 8D. I got 4 of those to replace the series 27's so now have a nice large bank equivalent to two 8D's.
 
#11 ·
We have 6 6 volt Lifeline AGM 6 volters. They are 4 years old and have had no problems. We got them because our batery bank is in a difficult spot to reach, they can be laid on their side so I have 6 instead of 4 bateries in the regular configuration, they are able to be equalized as mainsail said.

As talked about buying AGM requires you to look at your whole system to insure you are matching it with charger alternator etc. Also as mentioned they need to be brought back to 100 percet charge too.

We have ben very happy with them and have been the best batteries we have owned, but like all systems on your boat they require monitoring, but little maintainence.

Dave
 
#12 ·
I have Lifelines. I really like the customer support. They would be high on my list if/when I buy again.

I am not 100% sure agm's are always the best way to go. A high end wet cell may last beyond an agm. I personally have a large solar array and difficult access to two of my batteries, so they are the right choice for me. If I had good access to my batts, though, I would probably be looking hard at a high end wet instead.

SO, to answer your question, Lifeline makes a good product. I have sent many people there.

Brian
 
#13 ·
I find the differing views on AGMs between typical users and marine professionals to be instructive.

AGM users either swear by them or swear at them. Often, though, they imbue AGMs with almost mystical properties which in the real world don't really exist. They also tend to dismiss older technologies, like flooded lead-acid batteries, and gelled lead-acid batteries as being "dangerous", "messy", or "easy to kill".

Like MaineSail, I run across all kinds of situations in my daily work with batteries, and in my research. While I agree that in some situations AGMs can be a good choice -- and I'm about to purchase four 4-D Lifelines for a customer this week -- they're not a panacea for most boaters.

Consider this:

- flooded batteries will outlast AGMs every time in terms of charge-discharge cycles
- flooded batteries will take a lot more abuse than AGMs
- flooded batteries do not require expensive upgrades of online charging capability
- flooded batteries are a lot cheaper than AGMs
- flooded batteries are available everywhere in the world

and, consider this:

- in some situations, gelled batteries will way outlast AGMs and flooded batteries
- gelled batteries are nowhere near as delicate as generally depicted
- gelled batteries can be placed in any position, just like AGMs
- gelled batteries have the same no-gassing properties as AGMs
- gelled batteries are a bit cheaper than AGMs
- gelled batteries can take more charging current than flooded batteries, but generally don't require expensive charging upgrades
- gelled batteries have a much lower self-discharge rate, like AGMs

I'm not advocating one type of lead-acid battery -- flooded, AGM, or gel -- over another. I only wish to point out that choosing the right type of battery for your situation, i.e., your style of cruising, cruising area, geographic area, etc. is important.

Don't let anyone tell you that "AGMs are the only way to go".

Bill
 
#14 ·
On the other hand (there is always another hand) AGM's are the ONLY way to go if you MUST install them on their side.

This is my battery compartment - right now it holds 4 Group 24's - and as you can see it's a tight fit for them.

That's 320 AH - not nearly enough for a cruising boat.
I've got no idea yet where I'm going to put another bank.
I'll wind up with 2 banks plus a starter even though I really want one large house bank.

I'm thinking I may take the refridge and hook it directly to this bank - it sits under the sole in the salon, centerline on top of where the keel is).

500w of solar to a mppt controller should do it for both banks - the other bank would be a pair of 6v group 8's or 4's, echo charger to the start battery and the windlass battery.
 
#16 ·
I'm hoping I can MS - but not optimistic. I can't measure the space right now for a variety of reasons. My impression when I inspected the boat is that basically the space was as you see it, not deep enough for 6v's or wide enough for 27's or 31's.
There's only about 2 inches of above the batteries clearance for those 24's.
You can use my size tens for reference.

I just stuffed a pair of 6v GC2's in my Gemini in June when my Optima's gave up the ghost (5 years of supposed good monitoring) - those 6v puppies are tall.
Saved 70 pounds and added 1/3 the AH though.
 
#17 · (Edited)
I find the differing views on AGMs between typical users and marine professionals to be instructive.

AGM users either swear by them or swear at them. Often, though, they imbue AGMs with almost mystical properties which in the real world don't really exist. They also tend to dismiss older technologies, like flooded lead-acid batteries, and gelled lead-acid batteries as being "dangerous", "messy", or "easy to kill".btrayfors
Our decision to use AGM was not an emotional one but suggested by the top marine professional in the Annapolis area who outfits many of the cruising boats in Annapolis area as well as teaching marine elctronics in seminars at many of the boat shows and for the Annapolis Seamaship school. There are many factors in to deciding to use them and they are not as said a panacea or answer for everyone. I beleive true marine elctronics professionals look at the whole situation, intended usage and make their decisions based on that.

One of the most widely used arguments against AGM/ Gell is that they are more expensive. But are they really? The initial cost of the AGM is not just the only factor here. The cost of charging them must also be brought into the equation. This includes the charger, the cost of the energy to run the charge ( be it engine or genset), also the rate of discharge. The following is qouted from an article:

AGM is more efficient.
Based on Peukert's equations, the German scientist who mathematically solved the battery discharge problem, each battery's efficiency can be computed. AGM batteries are generally far more efficient than are flooded lead acid batteries. This is important when determining the cost to charge and discharge the batteries. Generally an AGM battery will give you between 80-90% of the power pushed into the battery, back. On the other hand, flooded lead acid batteries typically have efficiencies in the 40-60% range. The bottom lines here are time and money. Basically you spend more to charge a flooded battery than you do an AGM. This translates to money as generators eat gas, alternators rob horsepower from the engine, and battery chargers eat kilowatts. The real tragedy is that you get less of that power back from the flooded battery than you do with an AGM battery.

AGM self discharge rates are 80% - 99% better.
Batteries, being a chemical equation in flux, are not perfectly stable. A battery will self discharge as it sits. AGM batteries are far more resilient than flooded batteries when it comes to self discharge. The typical AGM battery will discharge 1 to 3% per month, with this rate remaining stable over the life of the battery. Flooded battery models do not fare as well, losing 5-10% per month when new, and up to 20 or 40% per month as they age due to antimony contamination in the negative plates.
Advancepowerproducts,com
Absorbed Glass Mat (AGM) batteries include lead plates packed between silica-glass mats, which hold electrolytes in suspension. They have no input current limitations allowing them to recharge more quickly than Flooded batteries, which typically accept about 35% of their ampere-hour rating, and Gelcells, that accept about 50%. At higher current loads AGMs also maintain usable system voltages for other high current, short duration loads as opposed to their counterparts, which become more inefficient during high current loads. AGMs also boast a longer lifespan than their counterparts, a deep-cycle flooded battery allows for 350 cycles at a 50 percent discharge level and Gelcells allow for 750 cycles whereas an AGM offers up to 1000 cycles at a 50 percent discharge level.
Gell batteries from windsun.com - they create solar charging syetms
Gelled batteries, or "Gel Cells" contain acid that has been "gelled" by the addition of Silica Gel, turning the acid into a solid mass that looks like gooey Jell-O. The advantage of these batteries is that it is impossible to spill acid even if they are broken. However, there are several disadvantages. One is that they must be charged at a slower rate (C/20) to prevent excess gas from damaging the cells. They cannot be fast charged on a conventional automotive charger or they may be permanently damaged. This is not usually a problem with solar electric systems, but if an auxiliary generator or inverter bulk charger is used, current must be limited to the manufacturers specifications. Most better inverters commonly used in solar electric systems can be set to limit charging current to the batteries.

Some other disadvantages of gel cells is that they must be charged at a lower voltage (2/10th's less) than flooded or AGM batteries. If overcharged, voids can develop in the gel which will never heal, causing a loss in battery capacity. In hot climates, water loss can be enough over 2-4 years to cause premature battery death. It is for this and other reasons that we no longer sell any of the gelled cells except for replacement use. The newer AGM (absorbed glass mat) batteries have all the advantages (and then some) of gelled, with none of the disadvantages
- flooded batteries will outlast AGMs every time in terms of charge-discharge cycles
with the proper care this is not really true. Ask how many sailors actually equalize their lead acid batteries monthly properly

- flooded batteries will take a lot more abuse than AGMs
This is simply not the case. The technology of th AGM makes them much more resisitant to vibration. In addition with AGM you do not have ANY acid problem. With AGM you have No spilling acid on your clothes when filling them or testing them, No discoloration or repair in your battery comopartment as there is no gas or sulfuric acid mist emitted during charging like with wet cells. This gas smells like rotten eggs---ever wonder why and what it is ( it is sulfur)
- flooded batteries do not require expensive upgrades of online charging capability
I agree that AGM systems must be matched more carefully, however there is no limnited rate for charging as their is for wet cells

- flooded batteries are a lot cheaper than AGMs
This has been discussed. Initially this is true, but when you add in the maintainence costs as well as the amount of the cost of energy ( wet cells take longer to charge to 100%, and must be charged at a higher point of discharge than AGM, and are less efficient in obtaining and making energy), ther longer the AGM lasts ( that is owners responsibility) the cost curve becomes a non issue. In other words a AGM which lasts 8 years will pay for the initial higher costs through the lower charging and energy efficiency costs. Plus NO Maintenence

- flooded batteries are available everywhere in the world
Obvious turth as they have been around much longer. As time advances this will not remain the truth. If you are cruising to Vanatu or the Solomons Islands this may be an issue. If you are cruising on the Chessie, United States or Canada this is a non issue.

Lastly in this, I have on a number of times helped fellow sailors who have been involved in a knockdown or a rough passage to clean out their battery comparments where there was acid spill and incidents caused by the wet cells movement during the rough seas. For safety is is so very important to do a good job of tying down and isolating your batteries so they dont move. With AGM this is a non isuue

With all respect to Bill ( whose posts a have huge respect for and have followed his advice many times) I think the main point here is whether you want to have a maintainace free system. Yes it is more high tech, sort of. As Bill and Mainsail have pointed out AGM are not for everyone. The proponents of it however are not just highly energized users or purchasers of the batteries, but professional marine electronics technitions also. In some of the sailors on here it may be quite and advantage to utilize them, and in many not so much to justify the added expense. You will need to do the maintainence though.

Batteries purchase is right up their as a topic on here with correct anchor, sail material and firearms in its many dimensions and ability to energize ( I like this word as you see especially when discussing batteries) the posters on here. Is there an always right answer to this. NO I think not. It depends on you usage and abilities and dedication to electrical maintainence. To long distance cruisers who thats all they do is maintain their boats...no brainer. To the average weekend user, maybe a different story. All sides can find factoids to support their own conclusions, just as I have. My recommendations are to consult a local to you marine electrontics professional to go over your specific usage and needs to help you make the most educated decision.

Dave
 
#19 · (Edited)
Our decision to use AGM was not an emotional one but suggested by the top marine professional in the Annapolis area who outfits many of the cruising boats in Annapolis area as well as teaching marine elctronics in seminars at many of the boat shows and for the Annapolis Seamaship school. There are many factors in to deciding to use them and they are not as said a panacea or answer for everyone. I beleive true marine elctronics professionals look at the whole situation, intended usage and make their decisions based on that.

One of the most widely used arguments against AGM/ Gell is that they are more expensive. But are they really? The initial cost of the AGM is not just the only factor here. The cost of charging them must also be brought into the equation. This includes the charger, the cost of the energy to run the charge ( be it engine or genset), also the rate of discharge. The following is qouted from an article:

Advancepowerproducts,com

Gell batteries from windsun.com - they create solar charging syetms

with the proper care this is not really true. Ask how many sailors actually equalize their lead acid batteries monthly properly

This is simply not the case. The technology of th AGM makes them much more resisitant to vibration. In addition with AGM you do not have ANY acid problem. With AGM you have No spilling acid on your clothes when filling them or testing them, No discoloration or repair in your battery comopartment as there is no gas or sulfuric acid mist emitted during charging like with wet cells. This gas smells like rotten eggs---ever wonder why and what it is ( it is sulfur)

I agree that AGM systems must be matched more carefully, however there is no limnited rate for charging as their is for wet cells

This has been discussed. Initially this is true, but when you add in the maintainence costs as well as the amount of the cost of energy ( wet cells take longer to charge to 100%, and must be charged at a higher point of discharge than AGM, and are less efficient in obtaining and making energy), ther longer the AGM lasts ( that is owners responsibility) the cost curve becomes a non issue. In other words a AGM which lasts 8 years will pay for the initial higher costs through the lower charging and energy efficiency costs. Plus NO Maintenence

Obvious turth as they have been around much longer. As time advances this will not remain the truth. If you are cruising to Vanatu or the Solomons Islands this may be an issue. If you are cruising on the Chessie, United States or Canada this is a non issue.

Lastly in this, I have on a number of times helped fellow sailors who have been involved in a knockdown or a rough passage to clean out their battery comparments where there was acid spill and incidents caused by the wet cells movement during the rough seas. For safety is is so very important to do a good job of tying down and isolating your batteries so they dont move. With AGM this is a non isuue

With all respect to Bill ( whose posts a have huge respect for and have followed his advice many times) I think the main point here is whether you want to have a maintainace free system. Yes it is more high tech, sort of. As Bill and Mainsail have pointed out AGM are not for everyone. The proponents of it however are not just highly energized users or purchasers of the batteries, but professional marine electronics technicians also. In some of the sailors on here it may be quite and advantage to utilize them, and in many not so much to justify the added expense. You will need to do the maintenance though.

Batteries purchase is right up their as a topic on here with correct anchor, sail material and firearms in its many dimensions and ability to energize ( I like this word as you see especially when discussing batteries) the posters on here. Is there an always right answer to this. NO I think not. It depends on you usage and abilities and dedication to electrical maintenance. To long distance cruisers who that's all they do is maintain their boats...no brainer. To the average weekend user, maybe a different story. All sides can find factoids to support their own conclusions, just as I have. My recommendations are to consult a local to you marine electronics professional to go over your specific usage and needs to help you make the most educated decision.

Dave
Dave,

You need to be careful with what you read on the internet. There are soooo many untruths and misrepresentations about AGM technology out there it can be simply laughable to those of us who work with deep cycle marine battery technology every day..

There are benefits to AGM batteries but much of what you read on the net about them is pure unadulterated BS...

In the real world of the marine environment GEL's typically last the longest, deep cycle wets not far behind and AGM, even if well cared for, come in behind both gel and wet. I would bet dollars to donuts that as a fellow marine electrical systems specialist Bill Trayfors sees the same as I do because I know we both on the same type of test equipment...

I base all my personal observations on battery life in the real world on actual measurements with industry standardized test equipment and the actual battery date codes. Most of the rubbish you read on-line about AGM's are white glove laboratory numbers not real world data like I see and deal with on a daily basis.

The sad reality is that perhaps 2-3% of the boats equipped with AGM technology actually take advantage of the acceptance rates and "faster charging" which IMHO is the real benefit to AGM's for "sailors" but there are other great benefits to AGM's...

IIRC your boat has an 80A Emaax alt and 660 Ah's of Lifeline AGM's. Even a 400Ah bank of wets would exceed the output of your alt in acceptance. Lifeline wants to see a MINIMUM of 0.2C or 20A per 100 Ah's of battery, for deep cycling applications. A MINIMUM of 20% of bank capacity.

If we figure your 80A alt can produce 70A when hot then you are at about 10.6% of capacity or roughly half of what Lifeline wants to see as a bare minimum. Wet cells will easily take 20-25%.. 25% of a 660 Ah wet cell bank would be an alt capable of 165A hot. That is more like a 180A "rated" alternator....

Lifeline actually warns that if the charging output is less than 20% of the banks capacity that cycle life can be "negatively affected". You can easily fit an Emaax 140 or 160 on that engine with a serp kit... I have done a number of 140A alts on 3 cyl Yanmar's..

Break in is also critical for all batteries and most yards, installers and boat owners are clueless about this. All batteries need to be cycled a few times and charged back to 100% capacity before the real capacity of the bank can be utilized.

When Bill talks about "abuse" I am fairly certain he means the "abuse" boaters put batteries through as in charging and discharging or lack there of, not vibration etc..

Still deep cycle wets and GEL's outlast AGM in my neck of the woods by a decent margin but about 85% of the boats I work on are mooring sailed and AGM's seem to dislike this more than flooded or gel banks (all based on real world, in the field, testing with industry standardized analyzers). I install a boat load of batteries, own the very expensive test equipment, install the charging systems and all I can say is AGM's CAN be the right choice but to do it right, which MOST don't do, can be a commitment and also costly.

As I said earlier AGM installations should be treated as a system and need to be treated as such. If they are properly installed they can come darn close to the life cycle expectancy of good deep cycle wets but I would not say I have ever seen them exceed wets in cycle life, even when properly installed.

I have the opposite problem on our boat. The alternator far exceeds our banks acceptance. I really could have an AGM bank, but I am waiting for my $210.00 bank of Wal*Mart wet cells, now nearing the end of their 6th season, to die. Can't seem to kill them though. BTW that same bank, if Lifeline, would have cost me $1170.00 at my cost.
 
#18 ·
chuckles.

Main may be right as Lifeline/ Odessey make all sorts of differeing footprints for the 6 volts other than the traditionl ones. We had that issue. I wound up making cardboard templates to make sure they fit before I purchased.

You access is great for maintainence

Dave
 
#20 ·
Fitting a larger alternator which I wanted to do with the serp belt was not an option to me due to the space my engine is in.

I guess I have wasted my money then as are many of us with AGM.
I guess the marine professional we deal with really isn't qualified in his recommendations
I guess the marine industry is duping many of us to buy the AGMs

One thing my marine professional has said to me is the same as you said. You can't beleive what you read on the Internet. Funny these comments are all on the Internet I am reading including the SailNet ones.

Luckily I have already gotten a few years on these Lifelines so I will be waiting for them to expire any day now. Or maybe they will actually last the 8 years I expected them to to beat all the negative expectations I keep reading about to make them financially worth while. I don't jut consider the initial cost of the batteries as the only cost. There is the other associated energy costs to keep them charged.

There is a space issue and access for maintainence which also lead to my decision. There was a safety one where I didn't want H2SO gasses on my boat and in the compartment where I live or spilling around if I had to ork on them around

One of the reasons I chose the electromax on your recommendation which was a good one was the % of charge at lower Rpm. I know that the bank should have a larger charger, but it simply won't fit.

I will show your post to my marine tech. Like both you and Bill it is what he does for a living and he is recognized by people in the Annapolis area as one of the if not the top company and person to use in this area. Maybe I as well have erred in using his advice and expertise. He is independent of brand use and presented me with 3 different scenarios for Haleakulas electrical system. This was the option he suggested. I tend to trust people I can look in the eye, but of course do research on line to try and back up my decision. What I read on the internet is all over the map. So who should I beleive? I choose the best I can from the informstion I get.

I will be interested in his reaction to you and Bills posts as he has a lot of real world experience and customers too.

Dave
 
#23 · (Edited)
Dave,

I don't think you've been "duped" as it sounds as if you made an "educated" decision. You may get your 8 years out of them for how you use them. As I recall you are on a dock. One of the big issues I face with cruisers and many of my customers is that they are not tied to a dock on a regular basis. AGM batteries like to get back to 100% and a dock sailed boat has this advantage over a cruiser or mooring sailed boat. I am still at a loss as to why a larger amperage Emaax would not fit? The 80A model and the 140A model share the same exact alternator case and have identical exterior dimensions.. Only the internals, stator & rotor, are different..

As I have said before AGM's can be the right choice, they have many benefits, space constraints are another good one, but I would be doing many of my customers a disservice by only recommending AGM because AGM's can be a poor choice in some applications for a number of reasons from financial to how the batteries will be charged.....

I install a lot of the 220Ah 6V 4CT batts because they are a standard height and will fit more Ah's than four group 24's will...
 
#21 ·
From what I have read, one of the big positives for going from wet to AGM is you do not need to change your charging systems. When I bought my boat it came with Gels and I could not be happier, when i need to replace them it will be with the same.
 
#25 ·
Here are some excellent links for some enlightening reading about a full time cruiser trying to use AGM batteries. I think John finally has it worked out but please DO read it all.. He eschews what I have been observing and trying to enlighten folks about for years. He does a GREAT job at nailing the "issues" and how to over come them.

These articles also display why I feel Lifeline battery is one of the best AGM makers out there. Justin has given John and Phyllis his full support and has NOT been bashful about having any of it posted on the internet so folks CAN get the best life out of Lifeline batteries..

AGM Batteries Test #1

AGM Batteries Test #2

Charging AGM's With An Alternator On A Cruising Boat

Problems With Using Battery Chargers To Charge AGM Batteries

18 Month Test Report

Equalizing Batteries On A Live-aboard Sailboat

Eleven Steps TO Better Battery Life

Direct Link To All John's AGM Articles
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top