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Old 07-23-2021, 11:09 AM   #1
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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?
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Old 07-23-2021, 11:25 AM   #2
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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.
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Old 07-23-2021, 11:50 AM   #3
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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...
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Old 07-23-2021, 12:16 PM   #4
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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
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Old 07-23-2021, 12:20 PM   #5
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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.

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Old 07-23-2021, 12:29 PM   #6
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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-raikfcquaxqnco...al-5-06-19.pdf
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Old 07-23-2021, 01:15 PM   #7
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Roger that. Thanks folks. This sounds like the winner:

Quote:
Originally Posted by Jeff F View Post
Or just put money in the piggy bank for a new set of batteries...
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Old 07-23-2021, 04:07 PM   #8
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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.
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Old 07-23-2021, 04:27 PM   #9
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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).
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Old 07-23-2021, 04:58 PM   #10
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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.
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Old 07-23-2021, 05:28 PM   #11
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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.
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Old 07-23-2021, 05:33 PM   #12
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Quote:
Originally Posted by Frosty View Post
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.
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.
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Old 07-23-2021, 07:19 PM   #13
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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.
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Old 07-23-2021, 08:38 PM   #14
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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.
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Old 07-23-2021, 09:07 PM   #15
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Hmmm, I am not certain. My guess is that itís the original model.
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Old 07-23-2021, 09:48 PM   #16
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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)?
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Old 07-23-2021, 10:05 PM   #17
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Time to jump down the lifepo4 rabbit hole
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Old 07-23-2021, 10:08 PM   #18
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Quote:
Originally Posted by firehoser75 View Post
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).
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.
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Old 07-24-2021, 12:21 AM   #19
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Quote:
Originally Posted by Jeff F View Post
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...
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.
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Old 07-24-2021, 04:10 AM   #20
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I am curious as to how the "Smartgage" treats SOC and SOH.
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.)
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