7 years old with total sulfation - testing now

[PNjunction]

Normally I don't play with battery trash, but I brought back a small 34ah agm that was SEVEN years old, new-old-stock and totally sulfated from 7 years of self discharge.

Victim: CSB EVX-12340 agm. Manufactured 8/2008 per sticker and heat-stamp on bottom. Rated 34ah but sitting at 4.2v ocv.

Found in buddies cool garage that never got used for anything, so I gave it a shot. I have a working year-old CSB 12200 20ah for another project, so that started the conversation.

Battery Tender did the classic immediate charge and drop to float - too sulfated.

Noco Genius and Optimate 6 chargers - both detected low voltage and went into higher voltage recovery. Both timed out after 5 successive restarts. This puppy is too far gone. Indications are either total sulfation, or a bad cell.

Battery Minder 2012-AGM. This worked! Battery Minder's do things the slow way with a different recovery method. It took 3 days to get out of intensive care, but finally stabilized as good. All error test led's finally went out after a few automated test/charge cycles. Left on float for 3 more days before minor discharge testing (20% DOD) revealed that it wasn't tricking me and acting somewhat normally.

I won't get into the subject of desulfation frequency sweeps, and whether this helped or was benign. That subject has been covered elsewhere. Regardless of how you feel about that subject, the charger did a great job.

Could I have done the same manually with a bench power supply, and a lot of time babysitting / tweaking voltage and current the whole process for 3 days or more? Possibly, but my time is worth just a little more than that.

I still have more testing to do. A few more days of cycling, and I'll measure the internal resistance (should be about 8 mohm for this model) and do a capacity test.

The CSB's are only rated for an 8 year life in float, so the fact that this thing isn't totally dried-out, doing endless absorb, or sucking down too much current in float is encouraging. Maybe it isn't totally dried-out.

I was expecting a bad cell, warped / shorted plates, dendrites puncturing the separators - you name it. So far so good and it appears that all I have is an undamaged old new-old-stock battery that was just totally sulfated.

I like my other chargers, so this isn't hype for Battery Minder - all I can say is that *under this condition*, the 2012-AGM charger did the trick, and did a very good job of it.

More testing results in a couple of days. I don't buy battery trash normally, but this freebie for testing I just couldn't pass up.

[PNjunction]

Recovery looks good!

Took internal resistance measurements, and according to that, all looks fine.

Using an iCharger 306b, measured the following: (note for new 306b users - the decimal point is not shown in the display, so don't freak out.)

CSB EVX-12340 3.1 mohm < --- recovered victim
CSB EVX-12200 6.3 mohm
Optima D51 Yellow Top 4.1 mohm

The readings for the 34ah CSB are actually BETTER than specification by about 3 times! BUT, depending on how a device determines IR, that can differ depending on instrument, ie Midtronics etc.

Since the readings with the iCharger line up with published specs for Optima, I'm going to assume that the method CSB uses is different, and not get too excited here. I now have a baseline that seems to be within the realm of reality.

Based on that, the 34ah CSB has a lower internal resistance than does my 38ah Optima D51! A secondary experiment has been started to see what the IR is on the Optima after a week or so of Battery Minder treatment. Later on that.

DISCHARGE TEST - I'm now doing the C/20 discharge test on the 34ah CSB, with about 1.75A discharge down to 10.5v. I could use the iCharger, but instead am using the Powerwerx inline power meter - which is actually fast enough to notice the difference in load demand with a dinky 100w msw inverter. The load is actually a 16w LED, and the current varies between about 1.3 to 1.8a very quickly as seen by the powerwerx. Nice.

I'll return in about 20 hours to see how this all shakes out.

[SunEagle]

If you are successful in bringing that battery back to life we may start to call you Dr Frankenstein.

[PNjunction]

It's BACK!

By George, I think I've done it!

I only achieved 25.75ah at the 18 hour mark when the inverter kicked off at 10.55v.

At first glance, this would be slightly under the 80% rated capacity value when most call it quits - especially when the published spec for float life is 8 years as well.

HOWEVER, when I look at the published discharge graphs comparing voltage / current / temperature to time, it lines up perfectly. Got lucky with 62F ambient today!

Since the internal resistance seems very reasonable, I think I'm there. In addition, I'm not sure if the plates are pre tank-formed, and could possibly use a bit more cycling to get them in the best shape possible.

I'm astounded frankly. This is not supposed to happen. I'm going to put it into service and see. My initial thought is that being 7 years old now, perhaps there is only a year left of good service and then natural aging will take it's toll. I totally expected at least some major grid degradation, but it doesn't seem so.

One thing I can say is that the Battery-Minder 2012-agm charger did it's job perfectly whereas the others gave up - which I don't fault since most batteries like this are truly trash and at times unsafe. I got the undamaged shelf-queen, aside from total sulfation.

Prior to placing it back on the charger, I gave it 90 minutes of rest, and the OCV was 11.45v.

Gotta' give these guys some thanks. And nice documentation:

http://www.csb-battery.com/english/03_support/01_support.php

That was fun. Note that this test was done on their deep(er)-discharge model, and not the general purpose type.

[PNjunction]

Recovery leads to further understanding on agm

It wasn't until I re-read the CSB docs that unlocked the last piece of the puzzle for me regarding agm and why a complete charge is so important. It has been oft said that it is better to slighty overcharge an agm, rather than undercharge, and here's why:

1) All vrla agm's are purposely made so that the negative plates are undercharged, while the positive plates are slightly overcharged. This is done on purpose to accommodate the recombination principle.

2) Because of that we are walking a knife edge between negative plate sulfation, and positive plate oxidation / corrosion.

3) This is also the reason that Optima (and some others) recommend a *controlled* constant-current / elevated voltage overcharge at the end of absorption to get the negative plates charged / devoid of sulfation, without burning up the positive. Most consumer chargers don't do that, so your best bet is to do either extended absorb, or a long float. Now I know what Dr Olson at Optima meant by doing this to get the best out of them. But you gotta' have the right gear / charger so as not to totally overdo it. Ridin' the knife-edge.

[LETitROLL]

It wasn't until I re-read the CSB docs that unlocked the last piece of the puzzle for me regarding agm and why a complete charge is so important. It has been oft said that it is better to slighty overcharge an agm, rather than undercharge, and here's why:

1) All vrla agm's are purposely made so that the negative plates are undercharged, while the positive plates are slightly overcharged. This is done on purpose to accommodate the recombination principle.

2) Because of that we are walking a knife edge between negative plate sulfation, and positive plate oxidation / corrosion.

3) This is also the reason that Optima (and some others) recommend a *controlled* constant-current / elevated voltage overcharge at the end of absorption to get the negative plates charged / devoid of sulfation, without burning up the positive. Most consumer chargers don't do that, so your best bet is to do either extended absorb, or a long float. Now I know what Dr Olson at Optima meant by doing this to get the best out of them. But you gotta' have the right gear / charger so as not to totally overdo it. Ridin' the knife-edge.

So I have a small 7ah agm that I also got free, it had been sitting at least 3 or 4 years but did still show around 11v on a voltage test. My smart charger checks it out for a minute then says "FULL". I read something in your thread that made me think I may have another option, I have access to a bench power supply with adjustable voltage 12~15, it has big panel meters for V and I, I should be able to hook it to that and play with the voltage and watch current flow? (babysit, as you said). I can discharge it some, and then do I try and adjust charge voltage until it accepts c/10, or because it is old and may also be sulfated should I be looking at something else as far as charge voltages and current rate?

[PNjunction]

Well, the simplest way to do this is to set the bench power supply to 13.6v.
Set the current to no more than C/100, or in this case 70 milliamps. .070A

Have voltmeter sitting on battery terminals. Watch for it to rise. When it seems to stall in voltage at the battery terminals, raise the current again just a little. Perhaps to 100ma. Watch for stall at terminals. Raise current again to maybe 150ma. and on and on. At some point later, raise the voltage to 13.8v and try again. We're talking hours to days of babysitting fun.

Thing is, I'm not much into reviving trash manually, so I'll let the smarter chargers do all the knob-turning internally for me. A battery minder 1500 / 1510 might be fun.

[PNjunction]

Getting a tad warm with 2012-agm model

Battery Minder 2012-AGM might be a bit too agressive for ups-style agm's ...

While the 2012-agm model brought back my decrepid CSB agm without any drama, or too much heat, NOW that is has been revived, it seems this model is a tad too agressive in normal use. Absorb voltages run up to about 14.8v, (temp compensated remember) and even though the CSB and most ups-style batteries like it have specs up to 15v, the battery is just getting too hot and possibly doing way too much recombining and not enough real charging.

Not uncomfortably so, but definitely noticeable at about 20F higher than ambient. This also occurs on my relatively new 20ah CSB, as well as an 18ah well kept Amstron.

Followup tests with the model 1510 do not get quite so hot, and the absorb voltage there is reaching a max of 14.5v at my temp right now. Batteries are just *barely* warm.

So - I think in the case of standard ups-style agm's like the CSB, Amstron, Powersonic, etc, the tamer model 2012 and 1510 are a better match for these general purpose types of agm's.

[Rainwulf]

Well, the simplest way to do this is to set the bench power supply to 13.6v.
Set the current to no more than C/100, or in this case 70 milliamps. .070A

Have voltmeter sitting on battery terminals. Watch for it to rise. When it seems to stall in voltage at the battery terminals, raise the current again just a little. Perhaps to 100ma. Watch for stall at terminals. Raise current again to maybe 150ma. and on and on. At some point later, raise the voltage to 13.8v and try again. We're talking hours to days of babysitting fun.

Thing is, I'm not much into reviving trash manually, so I'll let the smarter chargers do all the knob-turning internally for me. A battery minder 1500 / 1510 might be fun.

Would it be bad to just start at say 1 amp?

[PNjunction]

Would it be bad to just start at say 1 amp?

If totally sulfated, you'll know pretty soon from heat, as the current is too much for what in all practical purposes, is now a 1ah battery due to the medium to hard sulfation covering up what is available.

So that's why you start slow - at about C/100 and work your way up over time. It is a slow process, otherwise you'll just be emulating your smart charger that gives up the ghost real fast. And if you do it too fast for too long, the heat builds up enough that you start to warp things internally, possibly causing a short, or expanding the grids. In other words, the cure can be worse than the symptoms!

But go ahead and try it - as long as you are around to stop the process if it goes rice-crispy sounding, vents, or gets too hot. Go to a hardware store, and pick up a handheld infrared thermometer with laser-pointer, and point it all around the battery looking for hot-spots.

In fact, my revived CSB has a small hot-spot that may be the result of hard-sulfation. I'm still working with it, and each successive charge the individual cells are getting cooler during absorb - but this one spot may be impossible to get rid of. I'll be testing out the battery-minder desulfator to see if I can make more progress in this area.

[PNjunction]

FAIL - it died.

Although I brought it back, that hot spot in one cell never went away, and after successive cycling, it got worse to the point that when left unattended for a few hours (still within earshot), it never came out of absorb, accepting full current (less than 0.3C mind you), and went thermal. Too hot to touch and after 12 hours outside, it is still warm.

I should have known. It is already 8 years old, and sitting well below 6v for too long a time - totally past dead, and chemical nastiness going on inside. If I was there to get to it asap, that might have been a different story, but discharging well below 6v for a couple of years?

Kind of a waste of time trying to bring back trash, but I learned something. Can't blame the charger(s) in this instance. The Battery Minder did a valiant job bringing it back, but in the end, the Optimate was right from the get-go. I like them both for different reasons.