Water treatment for over sulfation

mcgivor · December 2016

Came across this and wondering if anyone has tried using this technique and if so, what the results were.
See page 24 section 2.25, of PDF attached.

BB. · December 2016

I don't know if it will work or not... The only possibly dangerous step is re-introducing the new acid back into the cell (do not add water/electrolyte to the strong acid--could cause an explosion. Always add the acid to water).

-Bill

PNjunction · December 2016

On a related note - even though you can't perform this technique on a sealed AGM, it is worth noting that when they are left to self-discharge for a long time, and the electrolyte acid/water ratio becomes more water than acid, some of the sulfate does now dissolve - but into the separators. (along with the normal grid-breaking expansion of the harder stuff).

Upon recharge, when the electrolyte tries to return to it's normal gravity, the once-dissolved lead-sulfate is now in the separator, and turns into a "hydrated short" with much higher self-discharge, or worse yet, a direct short across the plates when recharging is attempted. Once inside the separator, there's no turning back.

This is what a lot of agm trash-reviver's don't know. And why many automatic chargers try to detect cell-shorts either at the beginning or during the whole recharge process. If they don't detect a hard-core direct short, many can miss the hydrated-short, rendering the agm trash-reviver's attempts a fool's game.

softdown · December 2016

My efforts at chemical de-sulfation were an absolute failure. What the heck......what have you got to lose?

There should be a chemical solution somewhere that removes hard sulfate from plates.

Marc Kurth · December 2016

PNjunction said:

On a related note - even though you can't perform this technique on a sealed AGM, it is worth noting that when they are left to self-discharge for a long time, and the electrolyte acid/water ratio becomes more water than acid, some of the sulfate does now dissolve - but into the separators. (along with the normal grid-breaking expansion of the harder stuff).

Upon recharge, when the electrolyte tries to return to it's normal gravity, the once-dissolved lead-sulfate is now in the separator, and turns into a "hydrated short" with much higher self-discharge, or worse yet, a direct short across the plates when recharging is attempted. Once inside the separator, there's no turning back.

This is what a lot of agm trash-reviver's don't know. And why many automatic chargers try to detect cell-shorts either at the beginning or during the whole recharge process. If they don't detect a hard-core direct short, many can miss the hydrated-short, rendering the agm trash-reviver's attempts a fool's game.

I would add that a partial short will develop long before an obvious direct short. It's easy to see by watching the current draw along with temperature rise at abnormal levels. In practical terms, if the case is bulging out - it's too far gone to recover. That is not to say that flush sides mean "no short."

We have successfully recovered substantial capacity for many, many customers with abused batteries. But using the correct approach for the product is critical to achieve any success at all. Call me a "agm trash-reviver" if you wish :-)

For Concorde AGM's, step one for deep discharge recovery is a long slow (24-30 hours) process, using a low constant current with an upper voltage limit of 3v per cell. Once completed, an 8 hour equalizing run at 2.6v per cell is step two - then allow float for at least 8 hours.

If the standing voltage is on target, next is a high load rapid discharge to 1.75v per cell, with an immediate high current recharge at normal absorption voltage. If available, a charging current equaling the battery C20 rate is used. (100 amp charge rate on a 100 amp battery)

During the entire process, current draw and temperature must be monitored.
If current continues to climb unreasonably at the absorption voltage - we probably have an internal short.
If temperature climbs to 130 F, but current draw is steady, we terminate until the battery cools overnight.

Different AGM designs/implementations require different methods. Using the above method will immediately destruct some batteries.

Marc

mcgivor · December 2016

There is always a reason behind a question. In another post I have regarding a lazy cell in a FLA monoblock 12V, I've reached a point where the SG in one cell is between 1.150 and 1.210 and despite repetitive EQ's never rises beyond 1.210, tIme permitting . As a last resort, I was considering the water treatment process. The battery is in system is being discharged every night and the SG of the one cell rises every day, under normal charging, to the 1.210, so it is still somewhat alive, all other cells are 1.270, the battery voltage is about 0.3V lower than its series mate in a 24V series parallel setup, the charge and discharge currents are close. The DOD each night is around 10%, but it is cool right now so loads are light.
Soon I will be able to remove the afflicted battery and treat it on its own, without using it every day. So I suppose as I have nothing to lose, it will be an educational experiment if nothing else.

softdown · December 2016

Marc Kurth said:

PNjunction said:

On a related note - even though you can't perform this technique on a sealed AGM, it is worth noting that when they are left to self-discharge for a long time, and the electrolyte acid/water ratio becomes more water than acid, some of the sulfate does now dissolve - but into the separators. (along with the normal grid-breaking expansion of the harder stuff).

Upon recharge, when the electrolyte tries to return to it's normal gravity, the once-dissolved lead-sulfate is now in the separator, and turns into a "hydrated short" with much higher self-discharge, or worse yet, a direct short across the plates when recharging is attempted. Once inside the separator, there's no turning back.

This is what a lot of agm trash-reviver's don't know. And why many automatic chargers try to detect cell-shorts either at the beginning or during the whole recharge process. If they don't detect a hard-core direct short, many can miss the hydrated-short, rendering the agm trash-reviver's attempts a fool's game.

I would add that a partial short will develop long before an obvious direct short. It's easy to see by watching the current draw along with temperature rise at abnormal levels. In practical terms, if the case is bulging out - it's too far gone to recover. That is not to say that flush sides mean "no short."

We have successfully recovered substantial capacity for many, many customers with abused batteries. But using the correct approach for the product is critical to achieve any success at all. Call me a "agm trash-reviver" if you wish :-)

For Concorde AGM's, step one for deep discharge recovery is a long slow (24-30 hours) process, using a low constant current with an upper voltage limit of 3v per cell. Once completed, an 8 hour equalizing run at 2.6v per cell is step two - then allow float for at least 8 hours.

If the standing voltage is on target, next is a high load rapid discharge to 1.75v per cell, with an immediate high current recharge at normal absorption voltage. If available, a charging current equaling the battery C20 rate is used. (100 amp charge rate on a 100 amp battery)

During the entire process, current draw and temperature must be monitored.
If current continues to climb unreasonably at the absorption voltage - we probably have an internal short.
If temperature climbs to 130 F, but current draw is steady, we terminate until the battery cools overnight.

Different AGM designs/implementations require different methods. Using the above method will immediately destruct some batteries.

Marc

Charging at 3 volts/cell on AGMs? The more I learn...the less I know.

Marc Kurth · December 2016

It is important to keep the procedure in context as explained above - which is far from simply "charging at 3v/cell on AGM's"

To be clear, during the deep discharge recovery process for Concorde AGM Batteries only :
- The voltage is allowed to rise to that level if required to maintain a constant current of 5% of the C20 rating.
- This is performed in a temperature controlled environment and battery temperature must be monitored.
- There will be gassing.
- This is a slightly destructive process used in an attempt to get an abused battery back up to 85% - 95% of original capacity.

Marc Kurth · December 2016

mcgivor said:

There is always a reason behind a question. In another post I have regarding a lazy cell in a FLA monoblock 12V, I've reached a point where the SG in one cell is between 1.150 and 1.210 and despite repetitive EQ's never rises beyond 1.210, tIme permitting . As a last resort, I was considering the water treatment process. The battery is in system is being discharged every night and the SG of the one cell rises every day, under normal charging, to the 1.210, so it is still somewhat alive, all other cells are 1.270, the battery voltage is about 0.3V lower than its series mate in a 24V series parallel setup, the charge and discharge currents are close. The DOD each night is around 10%, but it is cool right now so loads are light.
Soon I will be able to remove the afflicted battery and treat it on its own, without using it every day. So I suppose as I have nothing to lose, it will be an educational experiment if nothing else.

Sorry to have derailed your thread! That was not my intent in responding to the other posts.
I cannot offer any advice on your weak cell - I'm strictly an AGM guy.

BB. · December 2016

The 18 volts is strickly a Concorde brand AGM battery deal... And follow their process (as Marc says).

The more you learn about batteries, you find out the less you know.

-Bill

mcgivor · December 2016

Marc Kurth said:

mcgivor said:

There is always a reason behind a question. In another post I have regarding a lazy cell in a FLA monoblock 12V, I've reached a point where the SG in one cell is between 1.150 and 1.210 and despite repetitive EQ's never rises beyond 1.210, tIme permitting . As a last resort, I was considering the water treatment process. The battery is in system is being discharged every night and the SG of the one cell rises every day, under normal charging, to the 1.210, so it is still somewhat alive, all other cells are 1.270, the battery voltage is about 0.3V lower than its series mate in a 24V series parallel setup, the charge and discharge currents are close. The DOD each night is around 10%, but it is cool right now so loads are light.
Soon I will be able to remove the afflicted battery and treat it on its own, without using it every day. So I suppose as I have nothing to lose, it will be an educational experiment if nothing else.

Sorry to have derailed your thread! That was not my intent in responding to the other posts.
I cannot offer any advice on your weak cell - I'm strictly an AGM guy.

AGM are still lead acid so there is relevance, interesting the high voltage, been using an inverter to center tap a 24V string, 2×12V, credit to Bill who suggested a light bulb to divert current, but needed more load, can get 15..45V across the one battery but thought 16V would be more effective, my array can't quite get there , it seems so close to breaking that 1.210 SG which it reaches every day. Perhaps I'm too optimistic, but nothing ventured nothing gained, or lost whatever the case may be, but once the gas is out of an AGM it's gone forever.

softdown · December 2016

Marc Kurth said:

It is important to keep the procedure in context as explained above - which is far from simply "charging at 3v/cell on AGM's"

To be clear, during the deep discharge recovery process for Concorde AGM Batteries only :
- The voltage is allowed to rise to that level if required to maintain a constant current of 5% of the C20 rating.
- This is performed in a temperature controlled environment and battery temperature must be monitored.
- There will be gassing.
- This is a slightly destructive process used in an attempt to get an abused battery back up to 85% - 95% of original capacity.

5% of the C20 rating is really low charging. What might be a typical current?

PNjunction · December 2016

Sorry guys - I think I'm the one that derailed the thread with the agm comment...

Marc - you aren't what I'd call an agm trash-reviver. There is a big difference between those that pop the tops, and those that apply a controlled charge / monitoring revival according to manufacturer recommendations...

I guess my point is that flooded or agm, once you pull back the veil of sulfation, there are secondary issues to deal with that make the battery unfit for original purpose. We are assuming that the battery was just left to discharge, and wasn't already gassed out by abuse beforehand..

1) The abandoned battery left to sulfate may have *already* served it's useful cycle life.
2) Revival, even if gentle and done properly, as we've seen, takes it toll on capacity AND cycle life down the road.
3) If the grids / cases themselves aren't swollen / broken by the hard sulfation, grids sitting around in low-gravity electrolyte corrode badly.
4) Initial test results may seem ok, BUT normal charge / discharge currents reveal localized "hot spots", making the battery unsuitable for what it was designed for in the first place, but may be ok with trivial low current loads.

I have performed so-called revival with either controlled charge currents like you do, (or even using Pulsetech products like the xtreme-charger and/or PP-12-L), but once the veil is lifted, the issues listed above make them unsuitable for serious consideration. Hot spots are what get me the most - the handheld IR meter makes it obvious if my hands don't pick it up early on.

(Note - the use of desulfators are covered in another thread - so I don't want to start it all over here. I'll just say that I'm using the *original* circuitry by Pulsetech, and not the horde of copy-cats or internet benchtop hacks that later followed with no lab proof, x-ray diffraction, microscopy photos etc). See that thread if you really want to go there. Basically I use it to help keep healthy batteries healthy, although I have revived badly abused stuff, only to reveal the earlier issues.

AND, my success in revival has proven more effective with "pure-lead" agm's, like Optima, Odyssey/Enersys and the like, over standard lead-calcium.

In the end, be it flooded or agm, the question to be asked is it REALLY worth your time to do all this, or just bite the bullet, start new, and treat it properly?

mcgivor · December 2016

Interesting stuff, and as @PNjunction mentioned is it worth the effort, it is educational if nothing else and since it seems nobody, here at least, has attempted the water treatment, or if they have, they're not talking, I'm going to give it a try and see what happens.The battery in question uses glass matt separators and is a lead antimony type and as mentioned, the cell not dead but will be if nothing is done. Got loads of time which would otherwise go to waste.

softdown · December 2016

^^^ I made a pretty serious effort at chemical de-sulfation with absolutely no positive results. Having been a biology assistant, the rules were followed pretty closely. One of 12 cells showed a slight increase in SG, most others went down a smidge.

Marc Kurth · December 2016

softdown said:

Marc Kurth said:

It is important to keep the procedure in context as explained above - which is far from simply "charging at 3v/cell on AGM's"

To be clear, during the deep discharge recovery process for Concorde AGM Batteries only :
- The voltage is allowed to rise to that level if required to maintain a constant current of 5% of the C20 rating.
- This is performed in a temperature controlled environment and battery temperature must be monitored.
- There will be gassing.
- This is a slightly destructive process used in an attempt to get an abused battery back up to 85% - 95% of original capacity.

5% of the C20 rating is really low charging. What might be a typical current?

Concorde states that 20% is minimum for repetitive cycling applications going to 50% DOD or more.
Technically, the maximum charge rate is 500%, but in reality that condition would only exist for about 5 minutes before the battery started drawing less current. In practical terms, 50% to 100% is more manageable because of temperature rise in common conditions. (Obviously not on a large battery bank!)

Your Fullriver batteries will happily accept 30% to 35%, but don't appreciably exceed 40% for any length of time.

Marc Kurth · December 2016

PNjunction

Yes indeed! Remember that my comments were based on trying to recover capacity from relatively new batteries (2-4 years old) that were accidentally allowed to sit at low charge levels for whatever reason. Typically this can only buy the customer another 1-3 years.

Marc Kurth · December 2016

@mcgivor - I am curious to see what happens too.

PNjunction · January 2017

McGivor - were those batteries new to you, or used / old stock? ...

In another thread, I think I've identified this battery as an "EFB" or Enhanced Flooded Battery, which uses the fleece surrounds to help in retaining the active material from falling away under heavy cycling and improve PSOC - typically found in vehicular batts like Varta / JCI's EFB line, or Yuasa's own EFB / EB line.

What may be a problem here, is a problem related to AGM's left to self-discharge too low - the "hydrated short" as discussed above.

This is really interesting - while you get kind of a cross-hybrid between flooded and agm (although not exact), you may also introduce some cross-hybrid problems, like the possibility of a hydrated short. Hmmmm..

mcgivor · January 2017

PNjunction said:

McGivor - were those batteries new to you, or used / old stock? ...

In another thread, I think I've identified this battery as an "EFB" or Enhanced Flooded Battery, which uses the fleece surrounds to help in retaining the active material from falling away under heavy cycling and improve PSOC - typically found in vehicular batts like Varta / JCI's EFB line, or Yuasa's own EFB / EB line.

What may be a problem here, is a problem related to AGM's left to self-discharge too low - the "hydrated short" as discussed above.

This is really interesting - while you get kind of a cross-hybrid between flooded and agm (although not exact), you may also introduce some cross-hybrid problems, like the possibility of a hydrated short. Hmmmm..

They were new to me and are a new line offered by Yuassa, of the 4 12V monoblocks all cells are perfect except one, and yes it was a over discharge when I was away during the hottest period. Seems according to the logged data the low voltage was 21.2 for several days, I'm guessing fans were used all night as the temperature was in the mid 40 deg.C overnight. This coupled with having the wrong panels, 60 cell as opposed to 72, meant the VMP during the day was not enough to charge with PWM, the mistakes we make and the lessons we learn. Yes I'm getting an MPPT CC to match the panels, before it gets hot again, during winter at 25 deg.C max it works ok.

As of now the SG rises and falls each day, cycling, but still on the low side, at one stage it wouldn't budge but after reptitive EQ's it improved but not to where I would like it to be . So just a few hours ago I set up another CC and will try this method without them being in cyclical use.

During the EQ there was at first, a hot spot on one side which would indicate a short, hydrated short? but that has since gone away. Would like to see a higher voltage 16v across the monoblock and can achieve it, but thought it best to take it out of use to deal with the process. So tomorrow it will begin and we'll see how it goes, for good or for bad, either way it will be educational. Oh yes, @PNjunction you are very far from my blast radius should anything go wrong...lol

mcgivor · January 2017

So day 1 of the water treatment for 1 bad cell
Start SG, 1220 @ 25 deg C fully charged
Recuced SG to 1050, EQ for 1 hour checked SG 1230 not temperature compensated
Reduced SG again to 1050, continued EQ 1 hour, SG 1220
Reduced SG again to 1050, continued EQ 1hour, SG 1150
Reduced SG again to 1050, continued EQ but ran out of sun after 45 min SG 1060, battery end temp 34.6 deg C

The cell was very active, gassing vigorously in a foam of small bubbles with occasional burps, as each hour ended the gassing had slowed but as soon as the electrolyte was further diluted, the action started again. So tomorrow I'll EQ to see if there is any more rise in the SG and if not, will begin the reversal process. My assumption is that as the cell was not completely dead, the time taken is less than a completely sulfated one, but something took place to raise th SG in each step, hope it is just the sulfated material.

mcgivor · January 2017

Day 2, SG @25 deg.C 1150
Diluted SG to1050, started EQ
SG still 1055, very little activity after 1 hour
increased SG to 1150, continued EQ for 3 hours, termination as batt temperature @40 deg.C, SG 1220, not temperature compensated.
Will start day 3 with SG reading @ 25 deg C

The addition of electrolyte SG 1300, in stags has reduced the gassing to small bubbles, nowhere near the amount of the electrolyte dilution stage, will see what happens tomorrow. Seems like I'm punishing the remainder of the cells for the sake of one, but so be it.

mcgivor · January 2017

Day 3, SG 1020@25 Deg C, start
EQ for 3 hours, temp 36 deg C, SG 1024 not temperature compensated
Put back into bank for regular service
Will see how things progress and wether cycling changes things.

mcgivor · February 2017

Been a little over a month since the water treatment, the results are positive, added a little more acid to bring the SG up to normal readings, the battery voltage is <0.1V of its partner in the string, was >0.8v before. The cell SG is close to the other cells in terms of readings taken when fully charged, evening and morning readings 1.270-1.240. The cell responds to charging in a similar manner to the others, gassing vigorously during EQ and the minimum daily bank voltage reading is consistent, the string charge current is close to ballance with the other string, so overall it was successful albeit how long it will last is another question.

Would I recommend doing this? Yes, if there is nothing to lose, you have the time, the ability to EQ for long periods and patience. Sun and temperature have been on my side throughout the process, the ability to isolate the battery from daily use was another. It was an interesting journey, if attempted don't try to rush the process, especially the last stage, it takes time for the SG to level out. Follow the instructions in the OP pdf if attempting to do this, my figures may not be 100% accurate.

westbranch · February 2017

How did the high local ambient temps affect the out come? slower temp recovery (drop) from the EQ sessions?

mcgivor · February 2017

westbranch said:

How did the high local ambient temps affect the out come? slower temp recovery (drop) from the EQ sessions?

Being mid winter the temperature of the battery in the morning would be in the low 20degC range, ambient outside temperature is lower but the concrete room remains stable, so this definitely helped as did the cloudless cooler days.

PNjunction · February 2017

Wow - thanks for documenting the results of your followup!

Glad that it worked out. I think a key issue here is that you got to the sulfate in time before it expanded and did physical damage to the plates / grids. Heh, just so dumpster-divers don't take a good thing too far.

Thanks for sharing that experience.

mcgivor · February 2017

PNjunction said:

Wow - thanks for documenting the results of your followup!

Glad that it worked out. I think a key issue here is that you got to the sulfate in time before it expanded and did physical damage to the plates / grids. Heh, just so dumpster-divers don't take a good thing too far.

Thanks for sharing that experience.

The cell was never completely dead and my thoughts are this may work on a battery with a known history, over discharged once, or as in my case a weak cell, attempting to restore a dumpster find would be an exercise in futility.

mcgivor · May 2017

Another 3 months have passed, the cell in question is performing well, pulling it's weight in the string of a parallel bank,, SG is good, voltages and charge/discharge currents equal. Overall it was a learning experience, something to seriously consider if there is a sulfation problem in one or more cells, but be forewarned it takes time, lots of it, having an alternate source for charging, other than the solar needed for daily use, would be hugely benificial. The battery is going to be replaced and put on lighter duty, a backup with light daily use, sort of a retirement, whilst I further evolve into something larger.

jonr · May 2017

I had success with recovering a functional but unbalanced battery with < 1% constant current for days.

mcgivor · August 2017

Whilst I understand this subject seems of little importance to the general member, I thought an update may be of interest to those who arre. The cell which was for all intense and purpose dead is now a non issue, it has been 6 months now and the SG is perfect, the battery as a whole has been assigned a light duty of supplying water pumping and lighting, also as a standby should my new system encounter any problems, which so far is no the case.

My most important finding is ,sometimes it's better to think outside the box, do something unconventional, have a single cell in a mono block that is in need of attention, or is not responding to regular charging? you might want to consider the water treatment, although tedious the rewards are encouraging, I took the risk hopefully to benifit not only my own situation, but others too, often I read of the one cell failure ruining a battery when the the other 5, or2, are still good whatever the case may be.

Water treatment for over sulfation

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