About eight years ago, we switched to Absorbed Glass Mat (AGM) batteries on Morgan’s Cloud, to get the following benefits over traditional liquid filled lead acid batteries:
- Shorter recharge times since AGM batteries accept a faster charge rate.
- No risk of the batteries freezing when we lay-up the boat unattended since AGM batteries have a very low self-discharge rate. (A fully charged battery won’t freeze, but a flat one will).
- About 10% more capacity in the same size battery.
However, our experience with AGM batteries has not been good: We have been through four sets of house batteries from two different manufacturers since the switch to AGM. When you consider that AGM batteries are as much as double the price of liquid filled batteries, that stings.
We should state at this point that we are tough on batteries, particularly at anchor when we are usually writing and working on photographs, using as much as 250 amp hours per day for lighting and computers.
However, we never discharge our batteries more than 50%, we have installed chargers and a regulator that have temperature sensors and purport to be designed to properly charge AGM batteries and we always recharge to at least 85%.
When the last set died after less than a year we had pretty much decided to go back to liquid filled batteries. However, before we did that we wrote to the manufacturer stating our concerns. What a pleasant surprise to get a helpful and concerned email from Justin Godber of Lifeline Batteries. A big contrast to the usual blow off, or worse yet, dead silence, that we are used to getting when we complain about gear that has not met our needs.
As we conducted a technical and detailed email exchange with Justin to try and figure out what had killed our batteries so early and how to avoid it happening again, it soon became apparent that we live-aboard voyagers are pretty much set up to fail as caretakers of AGM batteries :
- The yachting press and most battery experts, including Justin’s largest competitor, have told us that you should not equalise AGM batteries—wrong.
- Many, perhaps most, chargers and voltage regulators are programmed incorrectly for AGM batteries. This includes the ones that have a special AGM setting.
- Many chargers simply don’t behave the way they say they do in their own brochures and manuals.
More about all of the above in future posts.
Worse still, the accepted “wisdom” about AGM batteries is that all you need to do to enjoy a long life from them is to fully charge them after every discharge. Now, it takes two hours of generator or main engine time on Morgan’s Cloud to bring our house bank from a 50% discharge state to a 85% charge, but five more hours of charging to get from 85% to 100%. Fine if you are in a marina and can plug in, but totally impractical on a voyaging sailboat that may not see shore power for months at a time and that discharges the batteries by 50% on most days at anchor or at sea.
Yes, wind and/or solar power might help. That is if we were willing to use almost no power for the six to ten hours it would probably take those methods to top the batteries up to 100%, and that assumes a two hour generator run first.
So, we cut a deal with Justin: He provided us with a new set of AGM batteries for free and committed to advising us on their care and feeding. Our part is to write about the experience from time to time over the next year and thereby come up with a real-world set of recommendations, a manual if you will, on the use and care of AGM batteries (or any batteries for that matter) on a voyaging boat.
If you have any thoughts on the use of AGM, or any batteries for that matter, please leave a comment.
Disclosure
Justin bought one of my prints for his office wall and he, as stated above, provided two 8D AGM batteries at no cost to us. That is the only benefits we have received from Lifeline batteries.
Rest assured that if Justin’s recommendations are impractical on a voyaging boat or don’t result in adequate service from the new batteries, we will write about that too.
Ed C August 2, 2010 at 9:44 am
I am just in the process of replacing batteries on board my 40′ Pearson. Currently there are 3 but will add at least 1 or 2. I had decided on AGM for the reasons you had as well. I too have a charger that has a AGM setting and would be very interested to hear of your experiences as they unfold. Only 1 battery absolutely needs replacement at this moment so I have the option of pushing the replacement out a little and could use any advice or suggestions.
Thanks in advance,
Ed
paul August 2, 2010 at 10:05 am
I am still in the wet cell camp. More power per #, half the price, can service them (add water if needed in case it boils off or evaporates), and most importantly, no special charging methods. Just add batteries and go.
Never got fewer than 10 years on a set of (Rolls brand) wet cell batteries. I am tough on batteries. Leave them discharged too long.. Have flattened them many times over..boiled the batteries on the wrong setting…but no matter what I seem to do (not on purpose), they seem to come back to life, pretty close to 100% before my mess-up.
Got a Balmar alternator on our Ohlson 38, a short time motoring once in a while is more than enough to charge the 510 amp battery bank.
While a good product, AGM (and gel cell) are too pricey, too touchy to charge properly, and too few amps per pound for my take.
Robert August 2, 2010 at 2:05 pm
A known way to charge the battery close to 100% at each cycle without much trouble: split the battery into two separate banks. Each bank is used only every two days and the other bank is charged close to 100% during its “rest day” with solar, wind, engine or generator without increasing much the overall generator working time.
King regards.
John August 3, 2010 at 6:52 am
Hi Robert, Very good point. The only trouble is that to do that, and still not cycle our batteries deeper than 50%, we would need to double the size of the battery bank, something we don’t have the space to do. Also, if we did double the size of the bank, we might be better served by using the whole bank and only discharging to 25%? Not sure of this last point.
Finally, if we only charged half the bank at a time, we would not be able to fully load the generator since only half the bank would be in high absorbing mode.
Having said that, the system you propose might work great for a boat with lower power requirements than ours and with lots of solar and wind power. It would require some fairly complex wiring to route the charging current to the resting battery while making sure that it did not see any loads.
Hi Paul, Yes, we had Rolls batteries on a previous boat and they were great. If this experiment does not work, we will probably end up with them again.
Hi Ed, Hopefully what we learn from Justin, plus our own observations on how to get around the limitations of some charging equipment, will help on your boat–stay tuned.
richard August 3, 2010 at 7:01 am
Battery power must be one of the most elusive systems on any water-borne vessel that is designed to periodically operate sans fueled power (by definition this excludes modern-day ships and their massive generators although my guess is even these have crew with chronically disturbed sleep cycles because of this concern…do these vessels even have battery banks?).
These systems are so elusive because in spite of how they are supposed to perform and behave, they invariably don’t without constant manual monitoring and thorough experimentation (never rely on instruments except the multi meter, which has never let me down although learning how to use it effectively is also more of an art than a science as are ship’s batteries)…I remember thinking in my earliest days as a committed (serious) skipper that because their theory is so simple I would relegate the batteries to the bottom of the priorities listing…Needless to say hardly any time passed before I had elevated the batteries to the top of the priorities listing where they remain today, even more firmly established in their exalted status to the point that when my constant vigilance with them detects even the slightest hint of abnormal behavior or reading I am on it like white on rice till the abnormality is corrected, including the use of a maintenance-rated solar charger whenever my engine is still…I have learned that with the batteries a stitch in time saves at least 100 later on without exception.
Lastly, I have never departed from the use of the standard wet cell battery for exactly the reasons cited above by Paul…may the saints preserve us all where the batteries are concerned…
Matt Marsh August 3, 2010 at 8:23 am
I’m as surprised as you were, John, that your AGMs would be dying so quickly. Hopefully your experiments will reveal the cause of the problem- I’m betting on charger programming, but that’s far from the only possibility.
More sophisticated batteries inevitably bring with them more potential problems and the need for more advanced monitoring systems. Taken to the extreme, this results in the lithium polymer battery packs we used to use on solar cars, and that have now evolved for modern electric cars: 5 kWh or so from a 30 kg battery (the equivalent of over 400 amp-hours at 12 V), but each string in the pack needed real-time monitoring for over-voltage, under-voltage, over-current and over-temperature- any of which could result in either a string failure or a cell breach.
One thing that those Li-Poly experiences taught me was that, whenever possible, it’s best to obtain protection and charging circuitry from the same engineering team that designed the battery. If that’s not possible, then the different suppliers have to be willing to work together and provide each other with detailed specifications and all the characterization curves for their respective products. The battery guy, for example, should be able to give the charger guy a book of graphs relating voltage, state of charge, input or output current, charge acceptance rate, etc. for all foreseeable operating conditions.
John August 3, 2010 at 3:23 pm
Hi Matt,
You are absolutely right. As you will see as the series unfolds, the big problem is that the battery and charger manufacturers, in the marine business, are not on the same page.
Robert August 3, 2010 at 11:40 am
I have a friend living on his sailboat without shore power for several years. Only Solar panels and diesel generator. He uses standard industrial positive tubular motive power batteries, with two banks as previously mentioned, one day rest and 100% charged, one day in use and partially charged. After 7 years and about 1300 cycles, these batteries contain still about 70% of the initial Ah value.
The life time of this type of industrial batteries (2 volts elements) is about 1500 cycles at 50% discharge and C/5 discharge current, or 10 years floating. Their cost is much lower than AGM or gel batteries. About 1.5 – 2€ per Ah at 12 volt.
http://www.midacbatteries.com/beta2/site/siteING/prodotti_trazS.htm (there are many other manufacturers)
http://www.sunnyway-battery.com/Pro_Img/2006826915649392.pdf
Regards, Robert.
John August 3, 2010 at 3:20 pm
Hi Robert,
Thanks for the really good real world data. I’m sure it will be really useful to our readers.
Unless I’m missing something, this system requires a battery bank total capacity of four times daily use? That is unless the user is willing to run the generator more than once a day. For boats that can fit that number of batteries in, it would seem one of the best systems.
There is one other point: Most generators run at constant RPM and near constant fuel burn, regardless of load, therefore such a system will only be fuel efficient if the generator is sized to be fully loaded when charging half the bank (plus other loads) in absorb mode. Since the smallest diesel generators are around 5Kw this would, once again, imply about a 1000 amp hour battery bank at minimum. The other option would be a small gas generator, like the Hondas, or one of the newer technology variable RPM generators.
All of the above shows the importance of a total systems approach in all of this.
Robert August 4, 2010 at 1:15 am
The battery size:
At present, your battery is cycled between 85% and 50% . This means your battery size is about 3 times the daily need (85-50=35% of the capacity is used).
With two battery banks, each bank is cycled between 100% and 50%. This means your battery size is 4 times the daily need.
Robert.
Richard Elder August 4, 2010 at 6:54 pm
I personally can’t contribute any expertise, apart from a barrel full of stories about electrons that went astray.
As you may know, Nigel Calder received a grant of something like 500,000 euro to design and extensively test the optimal electrical/battery system for cruising yachts of our type. I spent a couple of hours chatting with him last fall at the Port Townsend boat festival. Asked him what he would choose for his own boat if he were paying the bills. His choice: new design thin plate lead acid batteries (Monarch & other manufacturers), along with purpose-designed regulator programing to take advantage of their high acceptance rate.
Might be worth a call to him.
Fair Winds,
Richard
Alan Teale August 9, 2010 at 3:11 pm
Dear All,
For one expert’s rather sobering comparison of battery types see http://www.sterling-power.com/support-faq-2.htm
Your boat may not resemble that on the web page, but I don’t think that is relevant.
Alan
John August 9, 2010 at 3:34 pm
Hi Alan,
Thanks for the pointer. A good article, albeit a bit simplistic, at least in my opinion. He does start with one wrong piece of information though and that is the relative cost of gel batteries. Our research has shown that gels are generally cheaper than AGM, not more expensive. Also, good quality heavy duty liquid batteries are generally more expensive than the number he bases his case on.
He is just plain wrong in his assertions about the fast charge rate of AGM batteries resulting in liquid loss and gassing. Actually, the exact opposite is true: AGM batteries, if not overcharged, gas much less than liquid batteries.
One other point, he is in England, where it does not often freeze hard. One of the big benefits for us of using AGM batteries is that we can leave Morgan’s Cloud laid up for months in temperatures down to -30c without having to worry about the batteries freezing due to self discharge.
Having said all that, I think that his basic premise that liquid batteries are by far the best value is indisputable. However, there may be compelling reasons to use AGMs that his overly simplistic analysis misses. Bottom line, I’m always skeptical of any article that claims to have the definitive answer for all of us.
Michael Slater August 10, 2010 at 7:59 am
I have had a similar experience, but with Northstar AGM’s. I have Victron Phoenix inverter chargers and the charge profile is based on the numbers provided by the manufacturer. The bank is temperature and voltage sensed at the bank, which is aprox 800 amps at 24v dc. My comprehensive monitoring ensured that the bank has never been below 75% charge. On anchor overnight I may consume 200 amps. On shorepower I make use of the power assist feature of the Victrons which although very small discharges add to the cycles. BUT I have had 2 banks in 4 years, £5000 down the toilet, and now at a loss to what to go to next. I have been considering Lifeline, using their 2v dc cells to create one bank, but frankly I am very nervous of AGM’s now.
Unfortunately I find the huge acceptance rate of the AGM’s very compelling, and the resultant low generator run times useful, however with some of the comments that not completing 100% recharge at EVERY cycle is a self destruct for AGM’s, I cannot see how these batteries can be any use for a cruising yachtsman who is regularly off grid.
John with this in mind how does Justin advise you to manage being on anchor? Run your generator for as long as it takes?
Help?
John August 10, 2010 at 8:08 am
Hi Michael,
Sounds like you and I are in the same boat (ouch, sorry). And you have an even better charging system than we do.
We will have a new post up later today or tomorrow on Justin’s recommendations. The key benefit of this post is that we have, between us, come up with a method that is practical on a voyaging boat. That is as long as it actually works, which we will only know after a couple of years.
Michael Slater August 10, 2010 at 8:30 am
John,
I am very intrigued to see the proposal, and if it stands scrutiny I would be interested in having a debate with the UK’s lifeline distributor on a bank for my boat this winter. If you can pass that on to your contact, Justin?, please let him have my email so I can have a rounded debate, I have already started debate with several suppliers here. Tell me, I know you got these for free, but in the real world what about warranty?? And it’s not just about the cost of the batteries which is a killer, it’s the back breaking removal and install that does me in!
Alan Teale August 10, 2010 at 9:12 am
Hi John, I think the point made in the Sterling Power article about gas and liquid loss on charging is that gas and liquid loss are not a problem with so-called sealed batteries or VRLA’s (AGM and Gel for example) precisely because they are, or should be, charged less aggressively than wet cells. And for this reason I am not sure why folk think that fast charging is a great feature of AGM’s. I do realize that there is some recycling of gas in AGMs, which mitigates the problem to a small degree.
May I ask if self discharge were not a major consideration for you, would you still favour AGMs?
And do you think the risk of spills and/or hydrogen production rules out wet cells on small sea-going vessels?
Alan
John August 10, 2010 at 11:53 am
Hi Alan,
With respect, I still think that you and the author of the article have it backwards. I have it on very good authority, and backed up by my 8 years of living with AGM batteries, that the whole point about AGM batteries is that they accept a higher charge rate than liquid cells without gassing. In fact AGM batteries actually like to be charged at their full acceptance as long as the voltage does not go over a nominal 14.4 Volts (at 70f). Note that to do this safely, the charger needs to be temperature compensated so that the voltage is dropped as the battery temperature increases.
In fact this is true of all lead acid batteries. The idea that charging slowly (below the battery’s maximum acceptance) is beneficial is one of the most persistent myths in battery care.
To answer your questions:
On balance, if self discharge were not a problem with liquid acid batteries I think that I would go that way because of the lower cost and the fact that if you do make a charging error (over voltage) and boil off liquid you can add more. But it would be a close run thing. When you have the capability to generate 150 amps plus of charge current in two different ways, as we do, it is really nice to have AGM batteries that can accept that for about 85% of their charge cycle, thereby lowering your generator or main engine run time.
And, no I have no problem with liquid batteries on an offshore boat. Batteries should be properly secured and vented anyway, whatever technology they use.
Justin Godber August 10, 2010 at 2:49 pm
Hello All,
I am Justin Godber with Lifeline Batteries. I have been working with John and following this blog. I thought I would start by responding to some of the topics above and clarifying a few things and answer some of the questions that will follow.
AGM batteries ARE a lead acid battery. So are GEL batteries. They all just contain the electrolyte in different ways. There are three types of lead acid batteries: Wet Cell batteries, GEL Cell batteries and AGM batteries.
Wet cell batteries as we all know are the type that you have to refill with water. They are messy and can be more dangerous because of the volume of hydrogen that is emitted during recharge.
GEL batteries have taken wet electrolyte mixed with silica sand to make a GEL. We used to make these until about 1989. As most people think this is a “newer technology”, really it is quite old and as I stated we actually stopped making these in 1989. GEL batteries are sealed and work well with very strict charging regimes. The biggest problem with GEL batteries is the charging and the vibration. With vibration the GEL forms all these small air bubbles. Similar to what you would see in a bottle of hair gel. These air bubbles virtually cannot go anywhere so they stay in the GEL. All is fine until all these bubbles sit against the battery plate. Any and all bubbles that are against the plate will not be able to produce any capacity because there is air there, not electrolyte. This may not sound like a big deal but there could be thousands of bubbles in there covering more than 50% of the plates. Secondly, the charging. Charging GEL batteries can be very temperamental. GEL batteries require very strict charging voltages and cannot really deviate 1/10 of a volt either way to avoid premature death.
AGM Batteries. This is important. NOT ALL AGM BATTERIES ARE CREATED EQUAL. AGM batteries have all the electrolyte absorbed into a fiberglass matting. They are then charged and formed and then all the excess acid is dumped out. We then seal the caps on the battery permanently. This results in a completely sealed battery. You can charge these batteries with 100% of their amp hour rating. This is a big advantage. You can charge a 100 amp battery with 100 amps. In fact they actually respond better in lab conditions when they are charged up faster. A Wet cell and GEL cell can only take 35% of their rated capacity on recharge. Making an AGM battery is like making a cake. The recipe has to be just right. We take pride in our batteries, we make everything (proudly) in the USA, and I mean everything. We also manufacture everything by hand. We have 17 quality checks as we are going down the line. We make batteries for Marine, RV, Aircraft, and Solar industries. We make a true deep cycle battery for the marine industry. Besides being very expensive to manufacture we really have no cons over any of the aforementioned battery types.
Now that all battery types have been explained, here is the part you have been waiting for. ALL batteries need to be fully recharged to avoid sulfation build up on the plates. I am not sure if I can post links on here so before I do I am asking. I can send links for Trojan Battery, Deka Battery, Odyssey Batteries, etc…They all state the same thing. Batteries must be fully recharged to avoid damage and premature failure. This is why:
As I mentioned before these are all lead acid batteries. They all perform the same chemically when charging and discharging. These batteries are all made from lead and lead dioxide and electrolyte. When the battery is discharged the plates go under a chemical reaction called lead sulfate. When the batteries are recharged this reaction is reversed. This reversal changes the plates from lead sulfate back to lead and lead dioxide. When the batteries are left to sit in a discharged state the lead sulfate does not get reversed and starts to harden, or crystallize. When you look at it under a microscope it looks like crystals. The longer it sits like that the harder it gets and slowly starts to grow farther around the plates. This is the part where I will tell you how sailors eventually ruin batteries.
Trust me, if I was in most of your positions I would probably do the same thing even knowing what I know. Batteries are not like a fuel tank. You cannot refill them to 85% and expect to always have 85%. As I stated the hardened sulfate will start growing. So when you use the 50-85 rule it works great for the first six months and then as the resistance starts to build and the sulfate starts to grow it goes 50-84 and then 50-83 and then 50-82 etc…Even though your charger says you are back to 85% it doesn’t really know because the resistance starts confusing the charger. It thinks it is back to 85% when it is slowly deteriorating. Eventually you will not be able to get the batteries above 12.2 volts and then we get a phone call.
There are a few solutions to avoiding this scenario. The easiest one for us, but not for you, is fully recharging every time. This will keep the batteries healthy all their life.
The other scenario when cruising is to use the 50-85 rule but you must equalize your battery bank once or twice a month. This will stop the sulfate from hardening as much as it would normally. John is currently using a similar scenario as field and we have had success in the past with some Trans-Atlantic crossings and they end up on the other side of the pond with fully charged batteries.
That last paragraph will bring up the next question. “I thought you couldn’t equalize AGM batteries”. Well, as I stated earlier ALL AGM BATTERIES ARE NOT CREATED EQUAL. I can only speak for our batteries but you can equalize them. It is a great tool to use on the aforementioned scenario. Also a great tool just in general to help clean off the plates and gain some capacity back.
Sailors have always struggled with all this battery/battery charging and we know why. We also know why you will only charge to 85%. As I stated I probably would do the same thing but we have been working and simulating your scenarios in the lab for years and we think the program that John is on is going to be successful.
I want to write so much more but I will wait for questions, concerns and comments so I can be more specific.
-Justin Godber
Lifeline Batteries
John August 10, 2010 at 2:58 pm
Great explanation, thank you, Justin.
If only more manufacturers of all gear would engage and try to solve problems, like Justin, instead of circling the wagons, maintaining voyaging sailboats, and just about anything else, would be a lot less frustrating.
Alan Teale August 10, 2010 at 1:07 pm
Hi John,
Understood. The article is a bit off with respect to AGM charge acceptance rates. But gelled cells seem to be another matter.
And thank you for answering my questions.
Alan
Michael Slater August 10, 2010 at 3:57 pm
Justin,
This is a great thread for me, do not mistake this from the following. I installed Northtstar AGM’s on the fairy tale sales pitch, now 2 banks down after 4 years I am stuck as I have described in a previous post. I want the benefits of AGM but how to get there if indeed they exist. You seem to have an evangelistic belief here so…if you have read my posts on my installation, why did my Northstars fail? Thin plates? Can you equalise thin plate AGM’s, AND more importantly what do I need to do to ensure that a Lifeline replacement bank does what it says on the tin?
I need to replace these batteries but with a long term commitment to survival!
I am not a tyre kicker here! I need a battery manufacturer who puts HIS money where his mouth (email) is…not mine? No insult intended.
As an aside if you create an 800 amp 24v dc AGM bank, is this best from 2v dc cells or another alternate, 6,8,12??
Michael
John August 11, 2010 at 12:01 pm
Hi Molly,
Now there is a good question. Sorry, I should have defined my terms.
Equalization or conditioning–strictly they are different, but we are going for brevity here–is a process where a fully charged battery is intentionally subjected to a higher charge voltage than normal for a fixed period. The idea is to break down the sulfate crystals that form on the plates due to repeated under charging.
We will be dealing with the “how it is done” bit in the next post.
molly mulhern August 11, 2010 at 10:41 am
Could someone give me a two-sentence explanation of equalization for an AGM battery? (what it is and how it is done?)
Allan August 13, 2010 at 10:36 am
I have been researching replacement options for my 9 year old Surrette wet cell batteries, now in their last season as they no longer hold a charge and after weeks of research one thing I have concluded is that it is not simply a matter of replacing my batteries but one of upgrading my entire electrical system. It seems obvious that AGM batteries are the way to go for me and for the same reasons that John and others point out…long cold winters, poorly vented confined spaces and the ability to bulk charge quickly. What I have learned from my research is that to use AGM technology to its max you must also consider upgrading your recharging and regulation methods accordingly. For us, cruising on our Bayfield 36 for extended periods has revealed that we are power misers when we need to be and also that we do motor at least half of the time due mostly to the sailing characteristics of the Bayfield as well as the prevailing winds here in Nova Scotia.
The 44hp Yanmar onboard is equipped with a 55 amp alternator that only produces near its max output at 2800 rpm which is also the recommended max sustainable cruising revs, but for fuel economy we normally operate around the 2000 rpm range. All this to say that in addition to battery updates we are considering replacing our 55 amp alternator with a high temperature 120 amp alternator that produces 85% of its rated output at idle speeds! This is a huge plus when using high load applications such as a windlass or an inverter. Remember that if an AC appliance like a coffee maker draws 10 amps at 120 volts, then the DC draw on the battery bank will be 10 times the current or 100 amps. Having an alternator that can provide most of this draw for the short periods they are used will reduce the drain on the battery and hence a faster recovery when topping up the battery. I also believe that the smart regulators available today are ideal for our boat needs as they provide three levels of charging and will accept inputs from many sources including wind turbine, solar, generator and alternator. What remains to be settled for us is the selection of the components so that our preferred option AGM batteries are safely charged and have a long life cycle.
John August 13, 2010 at 10:55 am
Hi Allan,
Great comment, thanks very much!
You may wish to wait for our next post before you actually buy anything in the way of regulators or chargers.
We have had some huge disappointments in that area over the last four years.
Bottom line, a lot of this stuff just does not work as advertised.
The offenders will be named.
Kettlewell September 24, 2010 at 5:56 pm
I’m in need of new batteries so these posts are very interesting. In the past I had a catamaran with no real engine charging, just solar and wind, and we had gel cells that were totally abused. They were discharged completely numerous times, charged without any sort of regulation, etc. and they were the longest lasting batteries I’ve ever had. I finally retired the original Sonnenschein’s after I think 10 years of use and abuse just because I was worried they would soon die, but they were still OK at that point. By the way, that boat sat over winter in Maine with a couple of solar panels hooked up and I never had a battery freeze, even when the snow covered the panels–it would eventually melt off. Subsequently, I have a different boat and went back to wet cell, deep-cycle batteries and they have routinely lasted about 3 years, which is exactly what I have found on numerous other boats. I have not owned Rolls, but in the past Surettes, and I couldn’t justify the price. Wet cells of almost any brand seem to last 3 years onboard and then fade rapidly. So, in recent years I buy whatever I can get cheapest. I’m now tempted to reconfigure to allow me to use cheap golf cart 6-volt batteries that can be obtained places like Sam’s Club because so many have reported such good success with them.
John September 25, 2010 at 5:22 am
Hi John K.
Great input, thanks. I too have wondered about the 6 volt golf cart option, but did not know that they were so generally available. Sam’s Club, who knew? We would be really interested in knowing how that works for you if you decide to go that way.
Also, we had really good service from Gells, in our case Prevailers. I have hesitated to draw too many conclusions from that because our usage was very different then, but still it is interesting. Perhaps Gells are not as fragile as generally thought? Anybody else have any experience, good or bad, with Gells?
Kettlewell September 25, 2010 at 9:29 am
Another thing I really like about the golf cart route is that you can actually lift each battery by yourself, facilitating the change out when you need to do it. Having struggled with 8Ds in the past, I find them just too unwieldy. My current set up uses a bunch of Group 31 12-volt batteries, which are liftable by a normal human. One the other side of the coin, if a battery dies when you are in some area away from civilization the chances of finding 6-volt golf cart batteries is not too good, but anywhere you find people you can find some sort of 12-volt battery. It may not be the ideal deep cycle, but it might be OK to help you limp along for awhile. I keep enough battery cable and fittings onboard to reconfigure my battery set up if I need to. Even a good set of jumper cables might help you out in a pinch.
ven.sona October 1, 2010 at 2:04 pm
It would be good to get some feed back from land based off gridders… we live on battery banks full time. We support up to 25 people with all electrical needs 365/ 24/7 through an 80 kwhr agm battery bank. The secret is: Charge at optimal efficiency with the generator up to about 90%, that is maximum for generator efficiency, the rest is topped off by solar panels. You need to time your charging for good sun following your generator charge. Of course, do as much heavy appliance use during your generator charging time as well since the generator is most efficient at 80% demand. Use a de-sulphater gizmo to continually break up sulpher crystals. Our first wet lead bank lasted 8 years, our new agm bank is into its 3rd year and performing beautifully. By the way, solar panel prices are less than half what they were 3 years ago. If you thought they were too expensive, look again!
Kettlewell October 1, 2010 at 4:10 pm
ven.sona sounds like your set up is working well for you. On a boat I think it is very important to have a set up that can compensate for less than ideal recharging conditions, abuse, and neglect, because in reality that’s what most boat batteries will see despite the best intentions of the owners. After refrigeration and engine problems, batteries and recharging are probably the #3 problem area on cruising boats.
Greg October 6, 2010 at 1:52 pm
John,
I’m a marine electrician and a sailor, and have had similar experiences to yours in regards to AGM batteries, both with my own boat and with multiple customer boats. I think the marketing hype behind AGM batteries made a lot of people jump on the bandwagon, and they are a poor choice for most cruising boats. If you find a way to increase the unacceptably short lifespan for AGMs on cruising boats I will be very interested to find out how, but I have tried many so-called solutions with no success. Also, I’m glad to see Justin is working to help you. My interactions with him and with Lifeline in general were so dismal that I won’t ever do business with his company again.
Regards,
Greg
Michael Slater October 6, 2010 at 4:57 pm
Hi Greg,
I am disappointed to hear the comments about Lifeline and Justin, I have found him most helpful. However I would be interested in your understanding for the failure of AGM’s and the specific solutions you have applied that have not proven successful. I am sure all those reading will be be interested in your findings.
Regards
Michael
John October 7, 2010 at 7:50 am
Hi Greg,
We had pretty much come to the same conclusion about AGM batteries for cruising boats. However, Justin (we have always found him helpful) convinced us to give them one more try.
We should have some solid data on whether or not they will last, using the protocol we have worked out with Justin, in six months or so, but our initial findings are encouraging. However if they don’t go at least three years with our daily deep cycles, we will go back to liquid filled. Stay tuned.
Charles Freeman November 1, 2010 at 6:40 am
John,
Thanks for a great series of articles. I think the best part is that you’ve gotten a manufacturer’s engineer to come out of hiding and talk in public. In my mind the most important thing he emphasized was that they are ALL lead-acid batteries.
I use wet cells, but I am following the thread because your recommendations are going to apply equally well to wet cells – because they are ALL lead-acid batteries.
I use Trojan T-105 6V batteries. I got seven years from my last set. I probably would have gotten another year or two, but had a knock-down that drained about half their acid out (successfully captured by my battery box, thank goodness) and by the time the passage was over they were toasted. However I am pretty hard on batteries – never equalized them in their entire seven years. (I will change that habit now, if I can – awfully hard to equalize batteries on wind and solar). There were a few years in the middle where we were CLODs and weekend sailors so the solar panel would bring them back to 100% during the week.
John K, if you only get three years from a set of wet cells, it sounds like you’ve got some systems re-engineering to do. That is way under par. Most of the cruisers I talk to here (I’m in the Caribbean) get 6 – 10 years from golf cart batteries like mine.
BTW, I had an AGM battery in an airplane once. Airplanes are like cars, they really only need a starter battery, after that the systems run off the alternator. No fancy charging or equalization, but the battery should nearly always be at 100%. Nevertheless the AGM only lasted two years, while we usually got five from a wet cell. That’s been my only experience with an AGM (Concorde brand).
John November 1, 2010 at 8:52 am
Hi Charles,
Thanks for a great comment. Really good point about AGM and wet cells both being essentially the same technology and requiring much the same care.
On the life of an AGM in a constant full charge application: The starter battery on “Morgan’s Cloud” is a Lifeline 4D that is eight years old. Still turns the diesel great. That would seem to suggest that Justin is right about the whole problem with his batteries failing in a year or so being traced to undercharging.
PAUL December 20, 2010 at 9:40 pm
Hi
I have 2x255ah AGM Concord for the past 10 years, living on board for the last 6. (4 POB)
Charging happens in the morning usually every second day. I run a 120 amp dc generator for about 1 hour then let the solar panels and wind generator top the last 10%. This works really well
and keeps my batteries and crew happy.
.
John December 21, 2010 at 12:42 pm
Hi Paul,
Sounds like a really good system. I have long thought that DC generators make a lot of sense for most live aboards. Why make AC just to convert most of it to DC to charge your batteries, as we do on MC?
Who made your DC generator?
Our problem with using solar and wind to top up is that on many, perhaps most days, we are on the boat and using more power than the amount of solar or wind generation we could install would generate.
Having said that, it would certainly help on days we were aboard and provide a good top up on days we were not.
PAUL December 21, 2010 at 8:05 pm
Hi John
I built the generator using a RK60 single cylinder Kubota.
I changed the cooling circuit to run through my colifier and back through a heat exchanger, this gives me hot water and power from the engine run. The motor runs at 2000 rpm and the noise level is 72 db so it just hums away in the background. I can also run a 140lt/h watermaker or a 4 stage dive compressor, so it’s a real little work horse and at about 0.5 lt/h very economical. If you are interested I can send some pic’s.
Regards Paul
John December 23, 2010 at 12:47 am
Wow, it sounds like a great machine.
For those that are interested. Here is a link to a commercial version.
Richard January 21, 2011 at 9:27 pm
Has anyone ever thought of contacting the writer of perhaps “the greatest book” ever written concerning all that you guys are talking about..?? (Yeah— Don Casey, writer of “This Old Boat”).. Or, just read pages 260 to 310 in his book.. Brilliant.. Just brilliant..
Don NZ September 6, 2011 at 11:50 pm
I am involved in my brother’s resurrection of a 50ft steel cruising sailboat. I’m planning a Victron Energy Multiplus inverter / charger, 200A dc main engine, Bosch alternator and Belmar MC 624 reg
6 – 8 x 120 w solar panels and Morningstar mppt controller and maybe a standalone multi role dc genset with another Bosch 200a and Belmar as written about above.
Still deciding on battery type. Currently 1000 a/hr of golf cart looks like a good option. Does Justin recommend AGMs for start also? If so is the charge regime the same? I had thought a separate engine start battery alternator may be a wise choice so do I then run 80 amp and lower the voltage or do the Bosch 200a with a Belmar MC 624?
Do you folks run your dc alternator at around 6000 rpm plus? What have you found works ok noise / efficiency / fuel consumption/ alternator cooling wise?
Boat lives in the tropics ( North Queensland Australia ). Mostly in marina, may go off the grid for a month each year.
Main engine is a 4 cyl Perkins diesel.
John September 14, 2011 at 2:46 pm
Hi Don,
I really can’t speak for Justin, but we have used an AGM as a start battery for years and found that it works fine. Our engine start charges along with our house batteries and while this would theoretically say that it is often being overcharged, it has lasted eight years, so far, so clearly it is doing it no harm.
Yes, a separate engine start battery is a very good idea. We simply charge ours in parallel with the house bank through a relay that pulls when we turn on the engine room fans, which is part of our engine start procedure. All much simpler than cluttering the engine up with two alternators.
Harvey November 11, 2011 at 4:39 am
After I had to replace on my Swedish Regina35 three 100AH LEOCH AGMs after only 3 years of useful life ( they are charged by a MASTERVOLT charging and monitoring system as well as a small solar charger), I spoke to a MasterVolt rep in the Bay Area, CA, about possible problems that may have lead to the batterie’s sudden death. He pointed out that often people don’t think to turn off the solar charger several hours before charging, which leads the controller to believe the batteries, showing higher voltage from the solar charger, are much fuller than they actually are which leads to undercharging. Another issue was the fact that we had to leave our boat after a cruise without fully charging the batteries, so the solar charger had to trickle charge them over days, and a third reason seemed to be the setup of the cables, which weren’t at the terminals at opposite ends of the 3 batteries in parallel. In the end the LifeLine Dealer tested my Leochs and found one in pretty good condition (80% capacity), the others, interestingly the ones further away from the pos and neg terminals where the main cables were positioned, in pretty bad condition. My LifeLine rep said they had tested different setups of connecting batteries in parallel and found that charging and discharging caracteristics wer quite different depending on where you connect the main cables to the terminals. We will see what comes out of my new LifeLines I just installed 3 weeks ago.
Thanks for your great posts!
Harvey
John November 12, 2011 at 1:00 pm
Hi Harvey,
Thanks for the very interesting comment.
My guess is that a very slightly poor joint at one of the cables, rather than the position of the cables themselves, was the culprit. A very small elevation in resistance caused by just a bit of corrosion will cause a surprisingly large difference in the charge voltage at each battery, and that in turn will result in the battery on the far side of the bad contact being constantly undercharged.
A good test to prevent this is to discharge your batteries to say 50% and then check the voltage with a high quality digital meter, at the positive of each battery against the common ground point while the charger is on. A difference of over one tenth of a volt (.1) is a problem, and less than one twentieth (.05) is worth striving for by cleaning all the contacts.
I don’t believe that the elevated voltage caused by solar charger is meaningful. Whether or not the battery will accept charge is a function of its own internal resistance, which is in turn, an indication of its charge level. The solar panel will charge it to what ever level it achieves when it is connected. When the AC charger comes online it will take it the rest of the way. In fact, it would make no difference to leave the solar panel charging in parallel with the AC charger. All of this assumes that both the AC charger and the solar panel are properly regulated and those regulators are sensing the voltage at the battery.
Harvey November 12, 2011 at 6:40 pm
John, thank you for your very helpful tip about checking the connections during a bulk charge for voltage differences to find problems with the cables, etc. I sure will make use of this with my new LifeLine batteries. Regarding your suspicion of a weak link in the cables I don’t think this was the case because not only did I check the cables and connectors, they also were in a like new condition: no corrosion or layers whatsoever, tight connections at the srcrews as well, threads shiny and clean. I don’t really know what to say what was the culprit if not the solar charger. I understand your point and I have to say: regarding battery issues there seems to be about as many different opinions out as there are people commenting – and pros obviously! Nevertheless, I am learing every day a little more
Harvey
John November 12, 2011 at 7:15 pm
Hi Harvey,
Glad it was of use. On the contacts, when you are dealing with low voltages and high currents (amps) just because they look nice and shiny, does not mean that they are without resistance. A contact that looks perfect can have just enough oxidation to cause enough resistance to unbalance the batteries. The only way to know is to measure with a high quality meter.
On the varying opinions. Next time you are trying to decide on the veracity of an opinion, ask the person opining to quote ohms law and explain what it means in one clear sentence and how it should be applied to the problem at hand. I don’t mean to be facetious here, or arrogant, but the sad fact is that I would venture to guess that some 50% of the “professions” in the marine electrical field would fail this test horribly. They simply don’t have the basic understanding of the underlying physics to adequately evaluate a theory about how to wire a boat. So what they do is take a popular myth and repeat it as fact to sound knowledgeable. That is why a good 50% of the “common wisdom” about batteries is just plain wrong.
On the bright side, most all of this stuff can be explained and understood using high school physics. I was fortunate enough to have ohms law banged into my thick scull be a very dedicated teacher some 45 years ago.
Harvey December 6, 2011 at 6:41 pm
John,
If it only was this, there are so many little issues that I don’t understand in spite of knowing that one very well. For example: My old batteries had a full load resting voltage of 13.0V. My new Lifelines have a fully charged resting voltage of 13.1. In terms of life expectancy and fine tuning, would you think that I should adjust the float charge accordingly, of course within the recommended limits (lifeline suggests 13.2 to 13.4), so stay at the upper limit?
a good test- ohms law
Greetings, Harvey
John December 6, 2011 at 8:51 pm
Hi Harvey,
I really would not worry about a tenth of a volt. Lifelines, in our experience, are just not that picky. Just follow the protocol that we have outlined, including regular equalization, and they will do fine, as ours are.
Don NZ December 6, 2011 at 7:15 pm
I wonder if a more accurate test might be to apply a load say around 50 amp. It’s value not critical it’s consistancy is . Every test use the same load while measuring the voltage ?
Regards Don
Don NZ December 6, 2011 at 7:19 pm
I use zero water vasaline or petroleum jelly on the terminals once cleaned and during cable assembly and have found it slows up the rate of corrosion.
Regards Don