A year and a half ago we installed a new house-bank on Morgan’s Cloud, and embarked on a field test of AGM batteries and the care regime that Justin Godber at LifeLine Batteries helped us develop. We now have some solid results.
Our Usage
First off, let’s put the results in perspective by talking about our usage. Since installing the batteries we have spent a total of six months in a marina with shore power available and the other 12 months out cruising.
When we are in the marina, we cycle the batteries to about 20% discharge once a day (mainly powering our diesel heater) because we turn off our shore power when we go to bed—the hum of the isolation transformer and the whirr of the charger fans is very irritating. A comparatively light use.
Once we get out cruising our batteries get a real work out with at least one 50% discharge every day and sometimes two.
So our batteries have seen some 180 20% discharges and about 400 50% discharges. They have also been abused by three 100% discharges for testing purposes (not recommended).
Results
We just ran a discharge test and are pleased to report that both batteries show just about 90% of their original capacity left, which is a huge improvement on the life we got from the last two sets that both died after about 400 50% discharge cycles.
While there is no knowing for sure, I would guess that, based on this test, we are going to get at least 1000 50% cycles and possibly as much as double that, before replacement—pretty impressive.
What’s Changed?
With the previous two sets of house batteries that failed prematurely, we had done all the usual things that conventional wisdom dictates, including installing a three stage alternator regulator and battery charger, and never discharging below 50%.
This time we took a much more active approach including reprogramming our alternator regulator from the factory defaults, equalizing our batteries once a month where possible, and manually managing our shore-power and alternator charging.
Conclusions
This has been an interesting and rewarding process that we have drawn the following conclusions from:
- The standard wisdom about battery care is flawed and, on a sailboat that spends most of her time far from shorepower, will result in premature failure.
- Most charging equipment, including the fancy three-stage stuff, that claims to automatically take care of your batteries, won’t.
- There is a huge amount of absolute rubbish published and rumoured about battery care, and the “professionals” are often the worst offenders in this regard.
- Most staff in boat yards are almost totally ignorant about proper battery care, but that does not stop them having opinions.
- (There are shining exceptions to the last two points, but distressingly few.)
- You don’t need a lot of highly expensive or complex gear to take care of your batteries properly.
- If you follow our relatively simple “Eleven Steps to Better Battery Life” you will do fine.
- The single most important of the eleven steps is monthly equalization.
- Batteries that can’t be equalized have no place on a cruising sailboat far from shore-power.
- The testing seems to indicate that good AGM batteries that can be equalized can last just as long as liquid-filled, although the latter can probably take more abuse since fluid that has been lost can be replaced.
Comments
If you have any questions or suggestions, please leave a comment. But before you do, please read the articles in the links below. To be blunt, we have done our homework, please make sure you do too, particularly if you are going to challenge our conclusions.
Further Reading
- Eleven Steps to Better Battery Life
- Details on how to equalize and some important cautions.
- The background and reasoning to the Eleven Steps
- Our testing methodology
Thank You
A big thank you to Justin Godber at LifeLine Batteries for providing the batteries and advising us as we tested them.
{ 25 comments… read them below or add one }
I’m glad to hear it’s working out for you, John. For an old and well-known technology, Pb-acid batteries are remarkably finicky. (Just wait until lithium-based cells start getting popular….)
“Most charging equipment, including the fancy three-stage stuff, that claims to automatically take care of your batteries, won’t.”
Anything that claims “install and forget” deserves lots of caution. It’s possible to automate everything, but it involves a lot of money, a lot of customization, a lot of sensors, and a lot of thick technical manuals.
“There is a huge amount of absolute rubbish published and rumoured about battery care, and the “professionals” are often the worst offenders in this regard.”
It does make it rather hard to do things right, when there are so many common ways to do things wrong….
The single most important of the eleven steps is monthly equalization.
This sounds like a lot , is there not signals from the batts that will tell you when you need to do it ?
And are they the same for: Leads, AGM, Gel ?
Geir ove
Hi Geir Ove,
Great question, thank you.
Yes, the sign that the batteries need to be equalized is that the charge rate starts to fall off more quickly than normal. Of course to monitor this you need a good meter with a shunt (step 9).
Having said that, we have found that while out cruising away from shore-power that once a month works well.
Also, you want to be careful not to leave it too long because the sulphate on the plates thickens and hardens with time. For example, while in Greenland this summer we were not able to equalize for a little over two months. By the time we got access to shore power the batteries were showing signs of pretty severe sulphate build up and it took two back to back equalization cycles to get them back up to charging properly.
If you are in a marina and fully charging frequently, you can probably wait 2-3 months between equalization cycles.
I’m pretty sure that this rule would be the same for liquid filled batteries, however the manufacturers of most Gells and some AGMs specifically caution against equalization, unlike LifeLine who encourage it.
More on Equalization, including some cautions.
In prior discussions I described in detail the very similar experience I had with AGM’s before John got Jason involved . Although I took a slightly different approach to battery management I can report a much improved experience the past 18 mos. My Lifeline banks and two other non -Lifeline banks of 4D’s; service has mirrored that of Johns. I contribute this much improved service to the equalization schedule and procedure recommended by Jason. My take away from this experience; do not trust what you read on battery care! Not all batteries are “as advertised”. Bigger (heavier) is not a good indication of performance. It’s all about quality construction and understanding how to properly care for your batteries in your particular circumstances, beginning with adopting a relevant equalization schedule.
Hmmmmmmmm I must be doing something wrong.
My batteries have averaged 8 years with nothing more than a Balmar ARS 4, Pro Mariner Fly Back and a jug of ionized water.
Hi Gene,
Hey, be happy! Although to make it a valid comparison you need to crank in the number of cycles, how deep those cycles are and how often the batteries are brought up to full charge as percentage of discharges. Without those variables the number of years that a bank lasts is not really a valid criteria.
For example, we have a 4D AGM that we use to start our engine that is 10 years old and still going strong and a generator start battery (Gell) that is 12 years old.
For more on what kills batteries, see this post.
Great information!
Regarding the equalization while cruising, I think you said you were at about once a month with shore power, but there may have been a 2 month hiatus from shore power? How long were your marina visits? How long did the equalization process take during these visits? Did you ever equalize from a generator during this period?
My real concern is that if, as you suggest, equalization is the key, how do you do this on the hook? As I see it there are two components, one.. what do you use to equalize whilst swinging on the hook, and two .. What do you do to segregate the essential systems from the high voltage necessary for the equalization process? (Perhaps you have the same problem whilst in a marina?)
Cheers
Tom
Hi Tom,
You will find the answer to most of your questions in the links at the bottom of the post, and the comments on those posts.
Right John, got that. I had just hoped you had some additional positive data and conclusions in these areas.
The bottom line is equalization demands two days with shore power per month, and constant monitoring for a minimum of 24 hours with at least some one awake, sort of like an anchor watch. If you have been out for longer than a month, say two months, you need to at least double that time. It just can not be efficiently done on the hook or whilst sailing/motoring.
For myself, a solo sailor, this seriously dampens the cost benefit reward for such a regime. While it may make sense for those with crew, for me it means an average of $50 bucks ( my average daily rate based on a weekly stay in a marina) for dockage and shore power or $600 per year. During that one day, I get no rest, and although I can do other tasks, I am completely tied to the vessel.
Currently T-105 lead acid batteries can be had for $160 a pop, about $120 if you have a core to exchange. So every year you could replace about 4 batteries, slightly better than 200 amp hours, for the cost of spending time at the marina equalizing.
I am thinking it makes sense for me to equalize whilst I am in a marina for other reasons, or hauled out, if I choose to spend my time for 24 hours monitoring, but regardless I will just need to accept that every year or so, I will need to replace a part of my battery bank.
Here is hoping you with a better mind on these topics than I can show me the folly of my thinking!!
Cheers
Tom
Hi Tom,
Your analysis is pretty accurate. As I say in my equalization post “hates the face off that”–a Newfoundland saying. Bottom line, I’m not at all happy about needing to equalize either!
You might want to look at solar cells and wind, which, if your usage is fairly modest, will reduce the number and depth of your discharges and also increase the number of times that your batteries are brought up to full charge. All things that will add a lot to battery life.
One thing to keep in mind, if you decide to go the route of cheap batteries and frequent replacement, is that failure from sulphation can be sudden and complete. In other words, you may be left in a an difficult situation far from a source of replacement when your inexpensive batteries, that seemed to be limping along, suddenly fail. And that is the voice of experience.
Do you have a monitor system like this on the Morganscloud?
http://www.argusanalyzers.com/index.php?id=31
Hi Carlo,
We have a Link 2000 battery measurement systems that uses shunts to accurately measure the amount taken out of the battery in discharge and the amount put back in charge. Also, this is the only accurate way to determine when a battery is fully charged.
See the links at the end of the post for more on how all this works.
Having said that, the “Large Pulse Resistance” technology sounds interesting and I think makes sense in theory, however, I would not trade my Link for it since it is not measuring actual use, which can only be done with a shunt.
Hi John,
Very interesting reading. I purchased 4 Sonnenschein GF-06-180v gell cells last year, and they were very expensive, so I would want to keep them for a long time. Their manual states a maximum charging voltage of 14,1V. There is no mention of equalisation or the effect of higher voltages once every time to return the cells to their optimum state. I am quite anxious to try this out and maybe throw away the equivalent of $1800!
Also, when moored (which is 80% of the time) I keep the batteries topped up with a small 20W solar panel. Would this have an adverse effect on the quality/lifetime of the batteries?
Kind regards,
Erik
Hi Erik,
On no account should you exceed the manufactures maximum voltage. If you do, not only are you risking wrecking the batteries, but there is also a risk of fire or explosion. As far as I know, most, or maybe all, gell batteries are not capable of being equalized.
And, as far as I know, as long as the solar panel is equipped with a quality two or three stage voltage regulator, a small panel like that should not harm the batteries.
Hi John,
Thanks. I will charge them as I did before. And yes, the solar panel is equiped with a quality regulator. I am going to upgrade to 3 20W panels, but I guess that will make no difference as the total capacity of the set is around 400Ah.
Kind regards,
Erik
Hi Erik,
Sounds good. I like your idea of adding more solar. Since you can’t equalize, it is going to be really important that you get as close to fully charged as you can after each discharge. See this post for why.
To me your batteri Lifeline seems low-quality. Allready 1980 UK manufactors said their AGM would last 10 years. Your equalization seems neurotic to me. On my expeditions shorepower is normal only after 60 days. I buy used AGMs, more than 10 years old, very cheap. There are hundreds of radio masts in The Arctic and they change batteries after 10 years. This batteries are cheap, but often ok. I only buy 2 volt batteries more than 5000 cycles. 12 volt batteries are not so good. With charging carefully at low volts they last for many years more and give plenty of power.
Batteries may fail and every expedition boat should be able to start main engine on compressed air or by hand. Sperre has a small hand driven compressor, its hard work, but takes no 12 volt.
Change to 2 volts and compressor and your problem is over.
Hi Svein,
Well that’s one approach! Neurotic? Me? I prefer anal retentive.
Seriously, I’m not surprised that very heavy duty industrial 2 volt batteries would last longer. In our case, like many other sailboats, we just don’t have the room for a bank of such batteries with the capacity to support our rather heavy electrical usage.
I also suspect that your boat may be a motor vessel, or at least a motor-sailor, that motors most of the time. If so, you batteries are getting fully charged after every discharge and are probably not being cycled very deeply.
The point being that when comparing battery life, usage changes everything. See this post for more.
Hi John,
I am sorry, I do not read much Freud. I have seen a German boat with 10 ruls how to pump the toilet, but 11 rules how to charge the battery is a record. I think your problem is that you have a big boat and small batteries. Big 2 volts last for 15-20 years, but they are big. Your ship is probably a masterpiece inside and has no room for big batteries, and you can not take the ax and make space. My sailboat is only 33 foot, but I make the space because I do not like the noice of a generator. My windmill is a plague. I now test new blue blades from Portugal. They are better.
My little sailboat has made 200 000 nmiles most of it north of the arctic circle in summertime. In summertime the wind is gone from that latitude, less wind for every 10 degree North. So engine makes 50% of the miles. That helps charging. I have also a motorboat that has made 120 000 hours. Modern motorboating is hard for batteries because people stay longer periods at anchor thanks to diesel prices. At Koster, Sweden you may now only stay 2 days at the same anchor spot. I am thinking of a generator for the motorboat.
You have good generator. Start it every day or sell it to me. I can give you some big batteries to put in the empety hole. (You must sail across.) . A wood fire helps, there is timber all over. Have you tried fuel cells? The Germans say it is very good: It makes no noice and batteries are always full. I do not know, but it could be the solution.
Hi Svein,
Oh no, we only have one rule for the head: you block it and the skipper will string you up by your thumbs!
Seriously, you are absolutely right, our battery bank, at 460 Amp Hours in too small for our daily usage, which, mainly because of this site, is around 200-300 am hours a day at anchor, and about the same at sea.
In a perfect world, we would have at least 900 amp hours and better still 1200, or four times our daily use. And in a perfect world we would have 500 gallons of fuel instead of 280…and so it goes. What the eleven steps do is allow us to manage with the batteries and the space we have at daily cost that we can live with. Just another compromise.
Yes, we do have a generator, and we run it every day at anchor, but that does not solve the problem. See this post for why.
Hi John, very nice talking to you! I also think a 1000 AH big 2 volts would do it.
To day it is cold here and I heat the ship with wood fire oven. That is charming and uses no el.. I still wonder about the Fuel cells, look at Efoy.com Have you got any experience with this tecnology? I am very curiose about this new metode of producing el.
Best regards Svein and greetings to your wife and your good ship
John
Thank you for posting your experience with your AGMs – I consider your Morgan’s Cloud report as so reliable I will be making my battery decisions based on it.
Focusing on your points of “regular full charging” and “monthly equalization”, I find that an onerous regime, especially since I do not have/want a diesel generator.
So I have decided on LiFePo cells as a house bank, the main attractions being:
a) Never needs to be equalized
b) Never needs to be fully charged (apparently 80% is enough)
c) Higher charge rates than lead acid (so when you charge, you can really pump it in)
d) Can routinely discharge down to 20% (as opposed to lead-acid’s 50%)
e) Can be left at rest, on its own, for 6 months, with low self-discharge
f) Half the size and weight of an equivalent lead-acid bank (friendlier than the 2volt 1000AH back strainers mentioned above).
The main downside (I currently understand; I’m no expert) is that you rely on an electronic cut-off device to ensure voltage remains between an upper and lower limit at all times. This high/low cut-off protection may not be dissimilar to keeping a Gel battery between upper and lower voltage limits, except that the voltage range is smaller, so the cut-off sensing must be more accurate.
You also have to keep an eye on inter-cell balance, but reading boat forums where LiFePos are used, it seems this can be monitored easily, and if re-balancing is required, is possible to do simply and manually.
So what do you pay for the above benefits? It seems that when you compare similar usable AH, perhaps in the region of two to three times as much.
(You can buy non-premium LiFePo at around $5.6/AH, but factor in that you can cycle 20%-90% as opposed to 50%-85%; also depends on the price you use for lead-acid, since there is quite a range).
Now, I do not have these installed yet, so it will be at least a couple of years before I could report on my real life experience, but we humans are ever optimistic.
Hi John,
I just wondered how you managed a typical days recharging while at anchor. Is it done through the generator and does the generator do other tasks each day as well, for example making water or running the fridge.
So for example, run the generator in the morning for 1 hour while making water, then in late afternoon again for another hour making a total of 2 hours a day.
At the end of the final generator run, how full would the batteries normally be?
Hi John,
When our batteries reach 50% discharge (no specific time) we run our AC generator charging the batteries through our three paralleled TrueChargers at 120 amps (12 volts). When the battery acceptance rate starts to fall off (about 75% charge), we turn on our DC holding plate refrigeration system that takes about 60 amps and runs for about an hour in 24 hours. When the fridge finishes the batteries are at about 85-90% of charge and we shut down. This whole routine requires about two hours of generator running. We would only run the generator again that day if the batteries reached 50% discharge again.
If I was putting together a boat from scratch, I would look at DC generators as well as solar power.
We don’t have a watermaker.
My Lifelines have done 4 seasons. Kind use with a 4 week vacation every year. The rest has been weekends and then back to the marina and the shore power. This year will be 6 month cruising. Much more demanding.
Honestly I do not expect the Lifelines to last longer than the Golf Carts open ventilated. Every battery expert that I have talked recommends open ventilated Golf Carts, if value for money is the only parameter. (Experts that offers both alternatives:-) )
I feel that the higher acceptance rate of AGM is only valid if you charge at the same voltage, 14.4V. Open ventilated can be charged with 14.8V which compensates for the lower acceptance rate. 0.4V makes a big difference.
But it is sure nice, not to have to deal with acid. Also it nice to know that the self discharge is low when you leave the boat in some odd place.