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Maintaining "Maintenance Free" Sealed Lead Acid Batteries  RSS feed

 
Posts: 55
Location: Valley City, ND.
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I have always wondered what would happen to those throw away, "maintenance free sealed lead acid" batteries if one maintained them much like a normal lead acid battery.  What kind of lifespan can they have if you bought one brand-new and then maintained it like a regular lead battery? 

Well I am going to answer that question with this thread.

I have gotten a hold of a fresh batch of brand new AGM (Absorbent Glass Mat) maintenance free sealed lead acid batteries.  Due to my background as both a manufacturing tech and a systems admin, I found I have had some very esoteric experiences with these batteries and their maintenance. 

For instance, I use to work for a hospital.  Even the pencils seem to have a backup battery attached in a hospital environment- so I have had a LOT of experience with both standard deep cycle, car type batteries and "maintenance free" AGM types.  I further maintain a huge UPS and generator where I work now.  It's got eight hours just in the batteries alone!  Everything except the heat\AC is able to run on the UPS for eight hours before the batteries need charging.  (Generator handles main lighting, AC\heating, the elevator, etc.)  So suffice to say I have some knowledge to give away when it comes to SLA-AGM batteries and standard deep cycle types. 

However, I have stated the above because if someone thinks I am an expert, they will take what I say with a grain of salt.  I am NOT an electrical engineer.  I am NOT affiliated with a battery company and I have NO specific training- other than from the School of Hard Knocks, with a degree in flying by the seat of one's pants.  Essentially, I have a lot of hard won experience with small systems using the equivalent of a car or truck sized battery, as well as the smaller SLA-AGMs used in alarms, emergency lighting and Uninterruptible Power Supplies. 

And let me say that I am a HUGE fan of what I call independent systems.  Those are small systems using a small solar cell or other charging system with a small battery.  I have found that many small systems is far better than one or two big ones.  The obvious reason is that if one system goes kaput, you can quickly swap to another, non-vital system as a replacement.  

And it's a LOT cheaper to learn with!

So those of you looking to do solar, wind, etc, might want to cut your teeth on small stuff like this now.  Otherwise, you could make some very costly mistakes with your off grid projects.  Small starts = small failures = BIG LEARNING.  A 7Ah battery can be replaced for $15 bucks.  A small solar charge controller for $20.  Start small, learn big.  And the small array can charge you electronic stuff during any emergency too. 

Ok, so now that my "credentials" have been established as a first class tinkerer and all around breaker of stuff to learn the hard way expert, I offer my obligatory "Don't kill yourself" warning.

Please DON'T kill yourself!

Batteries of even the supposed sealed type are not really sealed.  They emit hydrogen, which means in rare circumstances, they can explode.  Never seen it before, except as a young man using what's called a water welder.  Essentially, it is a device that uses hydrogen to develop a really hot, but nearly microscopic, flame.  Somebody turned the welder on and then decided to walk away.  They came back and lit the flame on the water welder...  The tip shot off and did an old west style ricochet off a couple of surfaces- and that was a microscopic welder.  So if you try really hard, you can cause an explosion with hydrogen from a battery or break one and spill acid all over the place and you.  If you drop one on your foot, you are looking at potentially some serious medical bills and pain.  So be careful.  But if you simply take a normal amount of care, you won't ever get hurt in any serious way- even by maintaining a maintenance free battery.

WORD OF WARNING!!!

I am confident that if you break the seal of a maintenance free battery, you break the warranty.  So be aware that your mistakes are OWNED by you. 

Ok, so as to actually maintaining a "Supposedly Sealed Lead Acid" battery, I already wrote up how to do that in a post about how to get these batteries for free and then return them to use here:  https://permies.com/t/84194/Salvaging-Dead-Absorbent-Glass-Mat

Check that out for the actual procedure on how to recover them and maintenance them.  The maintenance procedure is the same for new or used SLA's, so not going to repeat that here.

This thread is about making SLA's last as long as possible with some simple maintenance- is that even possible?  I will post my results here and share with everybody just how long I can make them last.  I have never done this with new SLA-AGM's, but I have with their brothers known as "low maintenance" batteries, car batteries, deep cycle, etc.  So this should be an interesting thread.  It's going to take forever and I will post my data here for everyone to see as we go along, but this is potentially really import to off grid users and people wanting to build homebrew power systems.

To start, I have four brand new 7Ah batteries.  They are the standard alarm and UPS batteries one sees in common systems.  They are cheap to buy- compared to a $150 car battery.  Retail auto part stores like O'Rielly's sell them for $30, but you can get them for $15 on the internet or even less.  It's the shipping that kills these things though.  Here's a picture.


Now I realize that many know what an Amp Hour is, but many are just starting out.  So here is the definition of what an Amp Hour, expressed as Ah, is.  Using the 7Ah battery, we can get one hour of use at seven amps from this battery or seven hours of use at one amp.  It's not perfect and you will get less than stated, especially as the battery ages, but it is at least a recognized standard for rating capacity.

IMPORTANT

Don't misunderstand that a 7Ah battery is a particular shape or size- it is a power rating only.  It refers only to capacity.  A 7Ah battery might be round, square or rectangular.  That's important if you are replacing your UPS battery.  The slots are made for only one size that matches a particular set of dimensions.   

I will have these batteries in a system with a 20 Watt, 12V solar panel and a 12V solar charge controller.  (Incidentally, this same setup can be used to charge anything that runs off your car battery.  Many small systems built to the 12 Volt system of a car will charge in this setup.  In an emergency, you can charge your phone, etc with a small mod of this system.) 

I will be posting the voltage of each battery after a full charge on the same charger brand new from the factory.  They will be "unsealed" and water levels checked and filled before they are charged, so I know I am starting with a good battery and not one that's dry already.  (Not a good thing for AGMs or any battery.)  I will let each battery sit until the voltage is stable too.  (Batteries will lie to you about their voltage when they are hot off the charger.) 

I will soon have four of the identical SLA-AGM batteries to test and I will record their voltage levels pre and post charge after making sure water levels are good.

Then out into the garden they go for a month on identical systems. 

I will then bring them back to the bench, check them for pre water voltage, then add water if needed and charge them again with the nifty little charge I have.  We will keep going like that all through Spring, Summer and Fall until the systems are brought indoors. 

That means this thread will be updated every so often with findings.  My theory is that  I will get over two years out of these batteries and they will still be going near new. 

Why?

Because when battery makers test their batteries and claim a two year lifespan, they don't actually do two years of testing.  And they don't break them open to see if they need water during the test, because they are maintenance free.  Further, they don't actually test them for two years.  They set them in a test rig and do a bunch of charge\discharge cycles that simulate two years of real world usage.

Now before anyone thinks that a conspiracy is to be found with maintenance free batteries, let me say this.  Yes there is a conspiracy and no there is not.  SLA-AGMs are made to be used and then tossed.  So all those emergency lights you see with headlights on them in stores and businesses and such, get replaced by law every two years.  That's a lot of batteries!!!  They build them as maintenance free - and they are.  So they break down at around two years of use.  I suppose the "conspiracy" is in the fact that the maker does not want you to crack these open for any reason whatsoever.  But they did bill these as maintenance free...  And there are some really good reasons why they don't want you to try and maintain them either.   

First, you might kill yourself and your widow will sue.

Second, the whole point is that maintenance people don't have to visit these batteries once every three months to add water.  They are MAINTENANCE FREE. 

Third, the battery companies are happy to sell you new batteries every two years.  I don't think that's evil.  They bill them as maintenance free and they are.  But I do think it's expensive- but not wasteful.  Here's why. 

The recycle rate on any lead acid battery is really high, likely way above 98%!  That's what "core charges" are all about when you replace your old car battery with a new one.  So there is really not a conspiracy here.

But there is in my opinion a way to save a LOT of money with just a smidge of time now and then.  Time spent taking the batteries out of use and filling them up with water, giving them a good charge and then back into the field.  I suspect that with correct use, proper sizing and just a little bit of care, one can easy get five years out of a SLA-AGM battery.  And one can repurpose them as they age for smaller and smaller things, like maybe running a night light for chickens, lol. 

So this will be a real experiment, even if it is a small one.  As I mentioned, I suspect one can seriously double or even triple the life of a SLA-AGM battery with this method.  Granted, it's a tiny sample.  But it is as far as I know, the first experiment of its kind.

And I will add more batteries as I get them.

If you have anything you would like to add or questions about SLA-AGMs, just let me know or post to this thread.

JR
 
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I have an absolute crapload of those small batteries and I tried to charge them with a conventional battery charger with little luck.
I'm going to the market to convert my pennies and nickels into an amazon voucher and order the charger you suggested right away.

I got the batteries from scooters where I planned to use the 24 volt motors for a variety of projects.

To date have not done a single one.
 
Jeffrey Rush
Posts: 55
Location: Valley City, ND.
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kevin stewart wrote:I have an absolute crapload of those small batteries and I tried to charge them with a conventional battery charger with little luck.
I'm going to the market to convert my pennies and nickels into an amazon voucher and order the charger you suggested right away.

I got the batteries from scooters where I planned to use the 24 volt motors for a variety of projects.

To date have not done a single one.



Make sure you have read the post on how to lovingly restore these before you try to charge them.  That's over here:  https://permies.com/t/84194/Salvaging-Dead-Absorbent-Glass-Mat

Follow that guide and you should be able to save some of these batteries.  But if any show as "CONNECTION BREAK" they need to be recycled. 

Remember what Obi Whang always says:  "The Charger is wise and powerful.  Use the Charger Luke." 

Honestly though, a lot will likely come up as bad if these have been sitting a long time.  But that's not all bad- recycled batteries bring big money at the scrap yard.  One tip though:  If you plan on buying new batteries retail, they will likely want an old one in return for the new.  Otherwise you will face a core charge.

If you watch the internet close, you can find a deal now and then on new ones- shipped free to your door and no core charge.

Lastly, make sure you get a multimeter.  You won't really know up from down otherwise, though the all wise charger can certainly tell you what the resting voltage is.  When you first hook up, it will display the voltage for a second or two, then begin charging. 

Best of luck and even if they all end up on the scrap heap, you will know they are ready to pass on and rejoin Obi Whang in wherever those glowy guys from Lucas world go to...

JR 
 
Jeffrey Rush
Posts: 55
Location: Valley City, ND.
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Brand New AGM Battery Low On Water


So I cracked open a brand new AGM battery last night, because the solar charge controller I was hooked up to showed it less than full.  That worried me, because I just bought this battery and charged it with this awesome little smart charge controller, the SKYRC iMAX B6 Mini, available from Amazon for $38.  I wondered why it was not showing as fully charged...  I continue to marvel at the small scale solar setup I put together.  I assure you it was something I stumbled upon- just dumb luck and a small budget, lol.  I was looking for a cheap system to pair with my vertical gardening system, which I will shamelessly link to here:  https://verticalfarmmechanics.com


Here's a picture of the SKYRC charger which I can't say enough good about.  It will be the base, "off system" charger to see how well that batteries are doing comparatively.  I will eventually be doing a set of AGMs without any maintenance as a control group too.  I have seen these for as low as $16 on EBay.  I paid $38 for mine on Amazon.  Whatever you pay for yours- it's worth it.  

SKYRC iMAX B6 Mini: 



Here's the link to the one I bought on Amazon:  https://www.amazon.com/gp/product/B018VP8P4S/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1


The "on system" charging device is a 12 Volt charge controller called by the generic name of "Solar Charge Controller."  Model Number: CMP12-10A.  Or "Anself Charge Controller."  They can be found as cheap as $6.50 on EBay- if you don't mind waiting a while for them to ship in from China.


Here's  the link on Amazon for the one I bought for $9.98US: https://www.amazon.com/gp/product/B007VLMRP2/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

So as I mentioned, the on system Anself solar charge controller showed the battery at less than full charge.  That bugged me and I wondered, "Hmmmmmmm, maybe this battery is older than I thought?"

So I cracked the top off- and was shocked to see the glass mat was dry....  I could see right down into the cells.  My experience has led me to determine that when water is less than just covering the cells, than performance is impacted.  Impacted as in the system is not using the entire surface of the system to retain charge and discharge current. 

So I filled it to the point that the cells were just barely covered with water and put it down for a gentle, 1/2 Amp charge.  How much water did it take to fill the battery?  Look at the picture below.


That entire glass was near the brim when I started and it took nearly all of it to fill.  Worked out to be 12 or more CCs PER CELL!  That's a LOT of water! 

Now there are those that say they know clawing at their eyes and screaming, "It's a maintenance free battery you idiot!  It's not supposed to have loose water in it!!! 

Well, that's not entirely true. 

These AGM batteries MUST be properly flooded in order to reach their full capacity.  And when the water is fully absorbed, there should be very little left free in the system.  Trouble is, how do you know where that point is.  You don't.  So filling it to just barely above the glass mat in the cell and letting it sit a while is the only way to know.   

So that's what I do.

It does leave just a smidge of free water in the system, which some people think is a sin.  But we will see.

I went back to the local auto parts store and asked them about the giant sticker on the battery that says: "2\18"  

I assumed that was the manufacturing date. 


Nope.  That was the last charge date.  Apparently, the shop keeps them topped off by occasionally charging the batteries on the shelf.  They scrape the old sticker off and slap the new one on- so it's really hard to know how long the battery has been sitting.

The moral of this continuing saga is, don't assume a new battery is actually "new."  It may have spent a good amount of time sitting on a shelf, losing water in the cells and therefore life in the battery.  I figure it can't hurt to top it off.  We will see, as I compare off the shelf, unopened, AGM batteries in identical, real world scenarios to ones I am maintaining.

But I find it a spurious argument to say that a really small, 7Ah battery needing 12 CCs of water per cell, was "full."  Even if it was a maintenance free battery, it's obvious it lost a lot in transit and sitting. 

As I mentioned, we will be comparing a set of maintained "maintenance free" batteries with identical types, that were used in an identical setup and never opened.  Stay tuned for our exciting conclusions! 

JR   
 
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Thanks for the amazing info on how to treat those batteries. Have a bunch in shed for some tests like this. Will report in future when I start on them.

Maybe I can add some info here too, about the charging process:
If you charge a lead-acid battery, it gets usually not enough time/voltage to fullfill its conversion from water to H2SO4. Most chargers are voltage-controlled and do not go higher than 14 to 14.5v. If however, if you use a current controlled (maybe a solar-panel that can match your batt-charge-current?) charger and you monitor the voltage you will notice that the voltage going first to a peak (dependent on batt but in the 15.5 to 16.2v range) and then settles somewhere in the lower 15v (with the charger still attached). This peak is very important as that is the moment that all sulfur is converted back into the h2so4, making the battery new. Needless to say that this is the reason why lead-acid batteries not last very long. The sulfur cristals building up over the lifetime and acid getting weaker and weaker. So if you build a charger (older ones with a transformer and a big rectifier did this too) you might create a double or even triple lifetime out of your battery bank.

Have done this type of charging with 2 9ah batteries (glassmat) with a solar panel and a relatively new car battery with an old type charger. All 3 batteries showed the peak. To my estimation you should do this to your car battery at least once a week to keep it in top condition (car charging-systems never go higher than 14.5v)

Probably does not work with old batteries as the bottom buildup of sulfur cristals/dust will be not easily be activated.

Please be adviced to only experiment with this in a safe manner. Acid is involved and can be dangerous if you are not know how to handle it
 
Jeffrey Rush
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Hello Tommy,

That's an interesting point.  I am far more on the practical user\maintainer side, sort of the Chief Cook and Bottle Washer of electrical systems in general.  That allows me to often test what is accepted electrical theory with real world experience.  Essentially, I am ignorant of theory and want to prove it myself.  Sometimes that leads to making discoveries that my brother, who is an Electrical Engineer ten times over, swears can't be right.  (I really don't know how many degrees he has, lol.)

Like rescuing an AGM before water levels get too low.  My brother said that was impossible.  But when I returned to life 3\4ths a stack of AGMs my brother certified as dead, he was willing to walk back from that conclusion.  (I have done something like that twice now, because I simply don't know what I don't know.  Therefore I try things that are universally accepted as "patently ridiculous" among those who should "know.") 

Often, I think the educated people in any field buy what they are told, because hey, they paid to be taught by the experts!.  And it may well be that the battery people themselves believe it too and not some sort of rip-off conspiracy.  Being as the battery people don't have a big incentive to investigate making their battery last too long, maybe nobody ever did the research?  So that's where absurd people like myself come in.  I call them "technical bumblebees."  We don't know it's impossible so we do it anyway.    

On the other hand, I have learned a LOT from the professional, highly educated guys and battery companies too.  There is most certainly something to be said for both ends of the spectrum.  Just be sure to keep an open mind and realize that what one is taught may have been learned a long time ago and accepted as truth- without a physical basis in reality.   

And it sounds like that's right where you are at.  The corner of theory and experience.  Your point might be dead on- and I am ALWAYS looking for ways to protect and further my system. 

Should any one of several disaster scenarios happen, I want to know I can make these systems last.  (like getting laid off!  Seven times in 10 years!)  Half of surviving any crisis is getting enough clean water to bathe, flush and drink and enough food to eat.  A battery system helps with all of that.

I have a lot of real world experience, but not a lot of "battery theory."  I refilled these AGMs initially because I had zero to lose- and could not afford a new battery!

But to your point, the charger I use for all my new batters initially and all my recovery work is an awesome "RC Hobby" charger.  It does every type of battery out there with special algorithms unique to that battery.  The "PB" (lead) setting runs real time showing the drop in amperage, but the rise in voltage.  At the end, it really trickles, like one tenth of an amp.  (1 mA.)  The voltage is surprisingly low to start, like around 10 volts sometimes, and surprisingly high, like 15 or better towards the end.  So I think what you are saying has some real world, practical applications.  I have often wondered about the "end game charge" hearing from many that this is the most delicate part of the charge.  Further, that because of this lack of finesse at the end of a charging cycle, most batteries don't die- they are murdered.  That's especially true of car batteries.  For 25 cents in components, car makers could fix this issue. 

My charger seems to be doing exactly what you suggest.  That being, converting the last bit of matter into energy storage. 

So perhaps I stumbled upon what you just said by accident- without ever realizing it until your post. 

I really can't say enough good about that little charger and it sounds like what you said is exactly what it is doing.  Refer to my other posts on the Sky RC charger for more data.  It's an ideal unit to have, as it can use any 12 to 24 volt power source, even another battery, to recharge phones, RC batteries, lithium, NICAD, and every other I know of, from 3 to 18 volts or better.  it works straight from a solar cell too!  (I am working to see if I can mod it for recharging disposable alkaline and standard disposables.  Yes, I know that's dangerous and the battery companies put cigarette level warnings on the battery that we should never, ever, do this.  But in a real crisis, how valuable would it be to have your neighbors pool their used up batteries for recharge?  Who cares if some of them fail at that point?  An alkaline battery at 80% recharge is better than an alkaline that you can't replace.  You would certainly be of immense value in your neighborhood at that point!) 

Another angle on this point, I stumbled across a great little solar setup.  You can read about that over in my vertical gardening posts.  I use the setup to water my vertical gardens.  A $25 epoxy coated, wickedly rugged solar cell for 12 volt systems and a $9 solar controller seem to do exactly what you say.  That is, they seem to know that a lead battery has a delicate end game charge.  I really need to wire that up to a volt meter and watch.  That would be sweet to see that solar setup treating batteries as they should be.  Normally, this small scale stuff tends to be slapped together, but the setup I stumbled upon is really well made.  It's been in the yard here in North Dakota for over two years now.  Thunderstorms, torrential Midwest rains, nearby lightning strikes, you name it, this little setup has seen it.  And it's going like new still.

Thanks Tommy for your input here.  I am going to start monitoring the end charge more closely.

And remember, batteries don't kill batteries, people do!  Take some time to care for them and they will last much longer. 

Anyone out there with more to add, please do!
 
 
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