Equalizing my AGM house bank

The three 198 aH 12 volt AGM batteries that comprise my house bank have started topping out at less than 100% State of Charge according to my Balmar SmartGauge. After days on shore power with my Xantrex inverter/charger on float, I am seeing SOC values as low as 88% Balmar tells me this is likely due to sulfation and that is consistent with my study and understanding of lead acid batteries.

The previous owner tells me the batteries were bought from West Marine in late 2019. The boat sat on the hard throughout the winter of 19/20 and until we bought it in September 2020. The boat had dubious charge "habits" while on the hard and while I had higher hopes, I saw 0% SOC at one point during the early winter of 20/21 before I disconnect the batteries completely. They did fine holding 12+ volts for the rest of the winter, but the damage had been done.

Through an email exchange with West Marine Customer Service, I get the impression that they do not want to say "yes, try equalization using these parameters..." Is that typical of West Marine? Equalization looks like a safe and smart approach to remove some of the lead sulfate from the plates. What am I overlooking?

Most AGM manufacturers (other than Lifeline) don't recommend equalization. If you pop the vent valves at all during the process, you'll be losing water from the batteries that can't be replaced.

Have they always been used in a bank, wired in parallel? I can't speak to equalization of an individual battery - I think it's of limited use with AGM - but it might be worth equalizing across the three batteries within the pack and/or testing each individually.

Or just put money in the piggy bank for a new set of batteries...

Had lifeline. Did follow SOC and health. Never ran them below 50% in fact very rarely below 80%. After 7 years all still good except starter which was replaced. Had friend on visiting who was much more knowledgeable than me. Told me in spite of the fact lifelines can be equalized they may off gas some. So to not equalize unless necessary. More important to treat them nice. We did do load testing periodically for each individual battery when either he or someone else could loan us the fancy meter. Just carried a simple multimeter

I agree with all of the above. You probably will be better off living with the 88% SOC until the batteries really die. Maybe if they get down to below 75% it might be worth a one shot equalization, recognizing that you may just be putting an arrow through them.

Equalization is designed to agitate the electrolyte to try to put the lead sulfate which is typically resting on the bottom with conventional FLA batteries back in solution. Agitation is caused by off gassing which as noted above will permanently reduce electrolyte if it escapes the valved vent. Also with the lead sulfate not on the bottom but near the plates in an AGM there isn't much value to be had from equalization anyway even if the loss of electrolyte were somehow controlled.

David

Lifeline was mentioned above. I don't know what brand your batteries are (ie. who WM bought them from), nor whether this would apply, but Lifeline has specific instructions all laid out in their excellent Battery Technical Manual (one reason I really like them - they give you all the information). They call it "conditioning," btw. They also have a "deep discharge recovery" procedure which is something like a more serious conditioning.

My 8-year-old Lifeline AGM house bank, I have conditioned once according to their instructions (about four years ago). Nothing vented as far as I could tell, and the bank is still my house bank.

Here is a link to the Lifeline battery technical manual:

https://321166-984045-raikfcquaxqnc...F-Lifeline-Technical-Manual-Final-5-06-19.pdf

Roger that. Thanks folks. This sounds like the winner:

Jeff F said:

Or just put money in the piggy bank for a new set of batteries...

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I just wanted to add something to my post above (past the editing deadline though). May not apply to the OP but perhaps would to a future reader.

When I equalized (Lifeline term: Conditioned) my bank four years ago, I kept close tabs on the temperature with an IR thermometer. No extra heat noted.

The bank is now 8 years old and still trundling along. I would consider going to LFP for the next round, but if I decided to stay with AGM I'd 100% buy Lifeline again. They were not the cheapest when I purchased them, but the combination of excellent technical data provided by them, real people on the phone if I had a question that was not covered, and the long life has made them an excellent value IME.

AGM's can be great batteries, but they are even more "sensitive" than FLA as far as treatment. The only way to "get the most" from any of these battery types is to treat them well, especially not operating regularly with a partial state of charge. Recharge often (daily is best) to a full 100% charge. At anchor it is almost impossible to do this without solar or some other low amperage, longer input time type of charging.
Unless access to the batteries is a problem, and you are looking for "best value" for dollar spent, FLA (golf carts) are probably still best bang for the buck. Looking after them is not a big deal. I spent literally 10 minutes per month checking on them and adding water when needed. To keep them in top form, I equalized them 2 times per year, following recommendations from Rod Collins of marinehowto.com. Having decent sized solar panels allowed my bank to obtain a 100% full recharge almost every day. FLA batteries like this. Full recharge, occasional equalization, and shallow discharge = long life (assuming normal maintenance). AGMs like this kind of treatment also (minus the equalization).

Good points, Firehoser,

I do have solar and due to fairly sunny location, the house bank gets back up to 100% most days. I also have a solar controller that allows me to set the charging parameters exactly as specified by Lifeline, plus an on-battery temperature compensation sensor*

In another, much earlier life, we bought a bank of AGM's without much knowledge of how to treat them (early days, not as much info available online, plus we were total newbs), and killed them within a season. No clue Looking back, we didn't have customizable charging inputs, no battery monitor, and inadequate recharge methods. We ran them until the stereo chirped. They were probably never at 100% after the day we installed them.

Luckily the knowledge available (and my understanding) improved quite a bit for the bank I have now.

Frosty

*I think this is vital. Even though my solar controller is literally mounted right to the outside of the battery box (so only inches away from the batteries), oftentimes during the part of the day that most of the re-charging is occurring (morning for me), the bank is a LOT colder than the controller. Overnight low temps plus lots of mass is what does it in my case (may not apply to everyone). So the voltage the controller puts out is adjusted quite a bit over what it would be if I relied on the controller's built in temperature sensor. The remote temp sensor was an option for my controller (Morningstar) and simply clicks into the controller and then an included (special) ring terminal on the other end goes onto a battery terminal.

Frosty,
I had a Morningstar controller as well. The Tristar 45 version with remote panel. I agree completely with the need for temperature (battery) compensation.
Personally, with over 500 watts of solar, and not using the inverter much, our solar would get our over 600 amphr. bank back to 100% everyday without running the generator (except very foggy days). I am a strong believer in solar on boats.

Frosty said:

In another, much earlier life, we bought a bank of AGM's without much knowledge of how to treat them (early days, not as much info available online, plus we were total newbs), and killed them within a season. No clue Looking back, we didn't have customizable charging inputs, no battery monitor, and inadequate recharge methods. We ran them until the stereo chirped. They were probably never at 100% after the day we installed them.

Click to expand...

Pretty good bet that nearly a year on the hard of unattended periodic charging combined with my newb status did ours in too. Great insights on the external temperature sensor. I'll have to look into our Xantrex inverter/charger to see if that is available.

I am curious as to how the "Smartgage" treats SOC and SOH. If they are not reaching 100% SOC - for a given health - then you'd think something isn't charging them right. I could see the SOH being 80%, but you should still be able to charge them to 100% SOC, expecting only 80% of new capacity. But there is a lot of Magic Juju marketing in the Smartgage that is not fully explained.

I'd be checking the charge voltage and amperage to see when the absorb phase is complete, then do a partial or complete capacity test to judge current SOH. If however they were left for a few weeks at 0% SOC, then probably this is a waste of time which might be better spent shopping for new ones.

Just curious, do you have the "original" Smart Gauge (voltage readings only, plus an algorithm, give you SOC) or the new SG200 which is a combo of a shunt-based monitor and the Smart Gauge?

I have been using the original Smart Gauge for 5-6 years but have not used the SG200. Since I set things up a while back (there was no SG200) I have a separate (Victron) shunt-based battery monitor, so with that and the original Smart Gauge I have both features.

Hmmm, I am not certain. My guess is that it’s the original model.

Yes, that's what I'm calling the original. IIRC it was developed by Merlin, which was a fellow on a narrowboat in the UK. Balmar put their name on it here.

BTW, that's the same one I have. No shunt, it just works by sampling voltage some huge number of times and then using an algorithm.

One note (which may not be appropos to your question) is that it is not at all reliable while charging. Once charging is completed I find that until I use some loads, it still isn't quite right. Once you are drawing power and not charging it seems to be very accurate in my experience.

They do explain that so it's not like a hidden flaw. Just the nature of the beast.

I also have a coulomb counter type meter (shunt used), so I'm able to compare and contrast.

So, if the Smart Gauge is all you have, are you looking at it either while charging or just after but before using some loads (seems to settle it down)?

Time to jump down the lifepo4 rabbit hole

firehoser75 said:

AGM's can be great batteries, but they are even more "sensitive" than FLA as far as treatment. The only way to "get the most" from any of these battery types is to treat them well, especially not operating regularly with a partial state of charge. Recharge often (daily is best) to a full 100% charge. At anchor it is almost impossible to do this without solar or some other low amperage, longer input time type of charging.

Having decent sized solar panels allowed my bank to obtain a 100% full recharge almost every day. FLA batteries like this. Full recharge, occasional equalization, and shallow discharge = long life (assuming normal maintenance). AGMs like this kind of treatment also (minus the equalization).

Click to expand...

You'd like to think so but ours are on their way out after 5 years
Batts only had 20% taken out each night and 2500watts of solar to smash the amps in.

Jeff F said:

Have they always been used in a bank, wired in parallel? I can't speak to equalization of an individual battery - I think it's of limited use with AGM - but it might be worth equalizing across the three batteries within the pack and/or testing each individually.

Or just put money in the piggy bank for a new set of batteries...

Click to expand...

Noting the OP`s agreement with the last para, I`ll add that once you accept replacement as the solution, you are free to try almost anything, there is little to lose.

DDW said:

I am curious as to how the "Smartgage" treats SOC and SOH.

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Just to follow up on this, the OP has the original Smartgauge (I also have one so am familiar with it). It has no shunt and does not report on SOH of the bank. It basically just gives voltage and SOC in percentage. It does this by sampling voltage some huge amount of times (thousands per something), and then using an algorithm to determine SOC. To me it has seemed amazingly accurate over about a six-year period. I judge that by noting the percentage and then seeing how many amps it takes to get through bulk and absorb and comparing the two.

I also have a shunt based meter (Victron BMV), but not sure whether the OP does or not.

It's the new Balmar SG200 that is like a combination of the original Smartgauge and a shunt-based meter. That one apparently gives SOH. (I think the SG stands for Smartgauge though so that's kind of confusing since there are now two different Smartgauges that work differently.)

Simi 60 said:

You'd like to think so but ours are on their way out after 5 years
Batts only had 20% taken out each night and 2500watts of solar to smash the amps in.

Click to expand...

Simi,
Not a total electrical guru or anything, but my guess would be "number of cycles". If I remember correctly, you are a full timer, therefore you would have the 20% discharge cycle daily? Many others probably cycle less than 100 times per year (seasonal use)??
Just a thought. Lots of info about your situation I don't know including battery chemistry, bank size....but battery life is often talked about in terms of depth of discharge and number of cycles.
Sounds like you have lots of solar!

firehoser75 said:

Simi,
Not a total electrical guru or anything, but my guess would be "number of cycles". If I remember correctly, you are a full timer, therefore you would have the 20% discharge cycle daily?

Click to expand...

I, too, wonder why Simi's have lasted such a relatively short time. I can only speak to the brand I have (not sure what Simi has), but I have been "full timing" for the entire eight years with my current battery bank. I would say I cycle down to about 80% SOC on average. Maybe once or twice per month down to 50-60% (string of cloudy days).

Most days I do get back to 100%, so my afternoon's usage comes "straight off the sun," so to speak. But I'm a night owl so the bank gets plenty of use after the sun goes down. On the 50%-60% discharge days it may be two days before I see 100% again - just depends on how sunny it is.

I'm not doing anything special nor am I an expert. I do have the precise charge settings on my solar controller, temp comp, etc. I also never use shore charging (but I bet Simi doesn't either), so they never just sit on a charger.

Simi: When you bought your batteries, were they a "premium" brand? Or just a more basic quality level (I don't mean to sound judgemental as there are good reasons for either choice just depending on situation). Are there lots of batteries in parallel so that "inside" ones don't get the same usage as "outside" ones? (You can wire to bus bars to eliminate that issue though.)

You strike me as the sort of cruiser who treats their batteries well, so I wonder if it was a quality issue from the mfgr?

Good points Frosty, especially about the potential wiring issues. All issues to be considered.

Flooded lead acid batteries will last just as long as AGMs used in the same manner as long as they are not abused. Depletion to 70 or 80%, pretty much no difference in longevity, even down to 50%. Only difference I see is, what, double the cost or more? And Lithium? I'd be dead before I would see any return on investment. Nope, FLAs for me every day.

Eight high quality (Trojan T-105s) can be had for about $1,100 or $1,200. An East Penn Group 31 deep cycle 12-volt AGM has 105 amps at the 20-hour rate. To equal the reserve of eight T-105s, nine of those AGMs would be required at about $400 each, $3,600 total. Wow, now there's a bargain. I could have three full sets of FLAs for the cost of one set of AGMs.

What am I missing? Must be something.

catalinajack said:

What am I missing? Must be something.

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Flooded batteries outgas and corrode anything nearby. AGMs (good ones anyway) don't. Yes there are some things you can do but they never seem to eliminate that problem. FLAs are supposed to be in an externally vented compartment for this reason.

The main detriment to longevity for both FLA and AGM is the owner, not the batteries. Most batteries do not die of natural causes, they are murdered by their owners. If cost is an issue, and your are going to murder them, then the cheapest are the best choice.

catalinajack said:

Flooded lead acid batteries will last just as long as AGMs used in the same manner as long as they are not abused. Depletion to 70 or 80%, pretty much no difference in longevity, even down to 50%. Only difference I see is, what, double the cost or more? And Lithium? I'd be dead before I would see any return on investment. Nope, FLAs for me every day.

Eight high quality (Trojan T-105s) can be had for about $1,100 or $1,200. An East Penn Group 31 deep cycle 12-volt AGM has 105 amps at the 20-hour rate. To equal the reserve of eight T-105s, nine of those AGMs would be required at about $400 each, $3,600 total. Wow, now there's a bargain. I could have three full sets of FLAs for the cost of one set of AGMs.

What am I missing? Must be something.

Click to expand...

Those East Penn G31 AGM batts, labeled Duracell, are less than $200 at Sam's.

catalinajack said:

Flooded lead acid batteries will last just as long as AGMs used in the same manner as long as they are not abused. Depletion to 70 or 80%, pretty much no difference in longevity, even down to 50%. Only difference I see is, what, double the cost or more? And Lithium? I'd be dead before I would see any return on investment. Nope, FLAs for me every day.

Eight high quality (Trojan T-105s) can be had for about $1,100 or $1,200. An East Penn Group 31 deep cycle 12-volt AGM has 105 amps at the 20-hour rate. To equal the reserve of eight T-105s, nine of those AGMs would be required at about $400 each, $3,600 total. Wow, now there's a bargain. I could have three full sets of FLAs for the cost of one set of AGMs.

What am I missing? Must be something.

Click to expand...

CatalinaJack,
I agree. I will state it again, the best bang for the buck is FLA (IMHO) and 6V golf cart batteries are a great option due to available AH for the size. On top of that, AGM can be even more sensitive to mistreatment than FLA, so a lot of owners not only pay substantially more for them, but "murder" them even faster than they would with FLA! (Thus adding again to the cost).

I have used FLA's for years and not noticed any corrosion problem in my applications. It could however, be an issue in some circumstances (esp. lack of ventilation or constant overcharging).

The downsides of FLA:
They must be contained in a battery box.
Must be oriented "caps up".
Requires a reasonable amount of ventilation.
Requires some "maintenance" and access to do same.
Self discharges faster than other chemistries, hence need for float charging.

If a boater has very poor access to their house bank, or requires an orientation other than "top up", then a different chemistry like AGM is a more expensive, but better choice. (IMHO)
Using your example (CJ) of costs (pricing), $2400 (extra cost above the FLA pricing) to avoid checking the fluiid level for 10 minutes once per month (and adding water occasionally) is in my opinion a high price to pay to avoid a bit of (easy) work. Over the life of the battery bank (estimated at approx. 7 years) that works out to saving $172 per hour of time spent "checking my batteries".
However, I do realize it is your money (each individual boater), and your choice!!

Frosty said:

Simi: When you bought your batteries, were they a "premium" brand? Or just a more basic quality level (I don't mean to sound judgemental as there are good reasons for either choice just depending on situation).

You strike me as the sort of cruiser who treats their batteries well, so I wonder if it was a quality issue from the mfgr?

Click to expand...

Most definitely Yum Cha brand bought from the big Victron dealer when we got the new inverter charger.
They reckon they had a good run with them so at $350 each we went for it (Full River, Victron, Lifeline all over $1000 each here)
They are still working, if you weren't looking at the gauges and putting a multimeter on them you would have no idea there is an issue.
Interesting that the "TBB Brand" can't be bought anymore or much if any info even found.

The boat really was a spur of the moment "Johnny on the spot" purchase
Whilst we were going to end up on the water at some stage, we hadn't planned for it to happen that week or even that year so cash was a bit limited at that point in time.
A bit more organised and a bit more liquid now. (-;

Are there lots of batteries in parallel so that "inside" ones don't get the same usage as "outside" ones? (You can wire to bus bars to eliminate that issue though.)

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There quite possibly is, I had a midget do the job so am not sure.
New batts (LFP) will be on the other side of the bulkhead back in the old coldroom with the inverter and MPPT, much more space there.

firehoser75 said:

Simi,
Not a total electrical guru or anything, but my guess would be "number of cycles". If I remember correctly, you are a full timer, therefore you would have the 20% discharge cycle daily? Many others probably cycle less than 100 times per year (seasonal use)??
Just a thought. Lots of info about your situation I don't know including battery chemistry, bank size....but battery life is often talked about in terms of depth of discharge and number of cycles.
Sounds like you have lots of solar!

Click to expand...

According to the Victron battery monitor
1 cycle
1184 synchronisation
Average discharge 0.2kw
Discharged energy 1366 kwh
Charged energy 4112kwh

Simi,
The term "cycle" I was referencing is each discharge then recharge is a "cycle". For most, that is one or two (2 means AM and PM generator run) "cycles" daily. Being a "dock queen" (constantly on "float") will affect the number of cycles (but I know that is not you). All things being equal, depth of discharge for each cycle will greatly impact the expected number of available cycles. According to most battery manufacturers there is a finite number of cycles in the expected "lifetime" that will decrease in number as the consistent depth of discharge increases. I am not familiar with the Victron monitor, but maybe your "synchronizations" is the actual number of "cycles" I am referencing???
Just found this interesting post on sailboatowners.com by Rod Collins of marinehowto.com. He is very good with all things boat esp. electrical:


Rod: "We recently capacity tested a bank of Trojan T105's and the batteries are 9 years old (March 2010). When new we commission charged them in parallel, then EQ'd them, and carefully matched them for internal impedance at our distributor during pick up. (I know not everyone has this capability). Today the are still producing 78.4% of the original rated capacity or 176.4 Ah's. While this is technically below the 80% industry standard threshold for end of life, it is darn good compared to most batteries we test at just two years old. How you use, charge and care for them can make a difference. This owner is pretty darn picky.

Usage Data:
This owner cycles them to no more than 35% DoD / 65% SoC (bank was specifically sized for this) and he has a fully gourmet charging system with all charge sources temp compensated and carefully programmed.

The batteries started out on a LINK 10 battery monitor but the owner added to a Smartgauge when they came out. FWIW the Smartgauge, before the batteries were removed, had them at 97% SoC and when we tested them here in the shop they wound up actually being at 95.8%. Pretty good SoC accuracy for 9 year old batteries.

Absorption voltages are; 14.7V (solar) & 14.8V (alternator) & shore charger. Float voltage on the solar is 13.6V and float on alternator regulator is 14.1V. Minimum absorption duration for solar is 120 minutes (due to the low charge current) and minimum absorption duration for the alternator is 240 minutes (due to the higher charge current) with a "high float" at 14.1V. Alternator rarely runs long enough to get to float though.

The batteries have been equalized for approx two hours, every four weeks in season, and then once before fall lay up for 4 hours, and again in the spring at 15.5V - 16V for two hours (temp dependent). The batteries reside on-board the vessel all winter 100% disconnected from each other and the vessel.

Charge controller is a Morningstar TS-MPPT-45 with temp sensor and full custom programming through MSView. Alternator regulator is an older Balmar MC-612 with battery temp sensor and programmed using full advanced programming menu. The rarely used charger (boat is on a mooring) is a Magnum inverter-charger which is also custom programmed.

The batteries also have Water-Miser caps. We will pull these from service, for coastal cruising, when they drop to about 65% of rated capacity. If he was going to Newfoundland again, we'd likely swap them now even though they are still fine for coastal use.

We find the difference between 5-6 years and 7-12 years is in the use, charging and care details...."