Generic failure in AGM batteries- no safety valves??

lazza · May 2016

HI Forum

Well we've been taught a hard lesson on cheap AGM 12V batteries. We installed about 70, at least 50 of them have failed in less than a year. Supplier doesnt want to know anything about it, and basically having done what we can to respond to our clients, we're having to take the supplier to court to try to recover our losses.

So anyway, examining the batteries and why they've failed I realised that although they claim to be AGM VRLA - I cant for the life of me find a valve on them. They only appear to have 6 screw-on caps. No valve (nor flame arrestor) to be seen. We are hoping to find a laboratory to perform a study that disqualifies the batteries as VRLA and that we can provide as evidence in court.

I was wondering if anyone in the forum is an expert on AGM VRLA batteries and knows exactly what requirements they should meet ? (and particularly to be sold in Europe). Any assistance, greatly appreciated!

Cheers
Larry

ps I've attached photos of the batteries and of their leaky caps!

westbranch · May 2016

Is there any indication of Country of Origin? you should be able to find that through the government offices for the EU including the specifications of an AGM, SLA or VRLA battery... as they are defined.... my bet is ''off shore'' source...

hth

Vic · May 2016

Hi Lazza,

Sorry to hear of this issue.

To me, an AGM battery has a Fiberglass Mat, that absorbs and traps the electrolyte, has plates constructed of Lead-Calcium, and one or two other metals (usually), had a Catalyst, probably in the cap, that recombines any gasses back into water. The cap has a fairly well-controlled vent pressure.

One would also expect that the Absorb voltage would be in the same range as Flooded Lead-Acid batteries, but perhaps on the low end of that range.

The Catalyst is EXPENSIVE, generally containing Platinum, Palladium in some combination, with perhaps some other metals. This recombining Catalyst is very important, as, without it, the battery will need to vent gasses, and these vented gasses are Hydrogen, and Oxygen, resulting from the breakdown of water in the electrolyte, and this water will be lost forever.

In the past, had wondered if some of the generic "AGM" batteries, might really be Gel types. IMO, most Gel batteries have NO recombining mechanism, and their "Absorb" voltage seems to be below Gassing voltage, as a result.

What is the recommended Absorb and Float voltage for these batteries?

FWIW, Vic

BB. · May 2016

Regarding the battery brand, this was about the most information I could find:

http://www.efimarket.com/media/pdf/Upower-UP-SP250.pdf

And regarding using Catalyst vs non-catalyst batteries--Here is an interesting paper:

http://www.tms.org/pubs/journals/jom/0101/nelson-0101.html

It does talk about the ability of batteries to recombine gasses without Catalyst--But the paper also seems to say that the Oxygen and Hydrogen recombination(s) are not a "paired process" (i.e., 2 H + 1 O = H2O Water). Very strange (at least with a quick read).

So--Some questions:

I would guess that a VLRA cap for those batteries should be set for ~1-2 PSI. The spec. sheet says they are "One-way valve regulated system with flame-arrestor"--One Way? Have you cut a cap apart to see if there is any sort of valving mechanism.
When you look through the opening (cap removed), can you see that these are not flooded cell batteries?
Is there any coating used on the cable terminal ends to reduce corrosion (sort of a problem here--Yes, AGM should be much "cleaner" batteries)?
Have you reviewed the charging set point voltages and battery temperature constant (-0.018 volts per degree c)?
AGM batteries will heat up about 2-3 faster than flooded cell batteries--So good ventilation is important, and probably (I would suggest) to not stack batteries touching side by side (better cooling if all sides exposed to air movement).
Have you looked at the actual battery operating temperature(s)? Are they running "hot"? I would say that a battery running over 35C/95F is pretty warm And if over 45C/113F is prone to damage/short life). The above white paper suggests that VRLA batteries running over 37C run the risk of thermal runaway.

If there was a problem "on your side", it would seem to be over voltage / over heating / too high of float voltage. As long as your equipment is in spec. and the ambient temperatures are "controlled"--I do not see how you can have so many "early life failures" that are not a problem with battery design or mfg.

Anyway, my guesses.

-Bill

lazza · May 2016

HI

Thanks for all your replies- in response:

- Made by MonBat in Bulgaria, hence theoretically should comply with EU regs
- Absorption not specified, but float specified on one of their datasheets at 13,8V- we normally put float around 13.5V and absorption at around 14.2V/28.4V (bit lower than normal FLA but to prevent overheating and gassing)
- These batteries falied in autumn, not summer temperatures, hence around 20ºC. No evidence of overheating, only liquid noted leaking out of battery caps.
- No valve present and certainly no flame arrestor- only screw-on caps- no valving mechanism within whatsever (see attached photos)

My theory is that with no safety valve and caps that arent air-tight, the batteries have lost their electrolite through the caps over a very short period- possible?

BB. · May 2016

I cannot tell from the picture if there is a valve or not--Just wash the cap out in water and try blowing through it (use a rubber/plastic hose?) to see.

I am wondering if the "one way" valve (if it was present) would be to keep atmospheric oxygen from getting into the battery cell--And oxiding the lead past/grid/etc...

It appears that internal battery components are very sensitive to presences of oxygen--Which tends to combine to whatever is available--Flooded cell batteries, the electrolyte appears to lessen oxygen contact/circulation with the lead plates/grids--And AGM/GEL/Starved electrolyte batteries in VLRA configurations use the ability of the battery plates/components to recombine the oxygen from charging--H2 may simply seep out the case wall?

-Bill

lazza · May 2016

HI Bill

Yeah tried all that- there's no vent at all (i've tried to take a photo with the white part taken out of the cap to show that there is no vent)- the only way gasses can escape would be through the grooves and red rubber "seal" of the caps

Vic · May 2016

Thanks lazza, for the additional photo.

There simply MUST be a venting mechanism. There appears to be a gap in the lower black area of the cap, at the bottom of the latest photo, where there is that raised rectangular red area.

BB Bill did ask about weather there appeared to be liquid electrolyte that you can see, when a cap is removed ... is any electrolyte visible in the vent well? If so, how much -- a lot, like Flooded batteries, or a bit, etc??

And, regarding the systems that use these failed batteries, What are the Charge voltage and time parameters? Are there parallel strings of batteries?
Are RTS/BTSes used on each charge source?
Where are these placed on the batteries?
Have there been any indications of battery issues, before the ultimate failure?
What is the battery model number/s?

Battery damage often occurs over an extended period of time, particularly, if that the battery is not being horribly abused .... and so on.

Thanks, Vic

Dave Angelini · May 2016

You installed batteries for clients that were unknown to you? Sounds like one of the ways to fail a business.

lazza · May 2016

No, never really had big battery problems before. With 12V FLA had some early failures, but normally after a year or two because the client didnt replace the water or over-discharge. Yes there was some liquid in the caps similar to a FLA, yes you can see a bit of liquid above the spongey white substance between the plates. Definitely no vent in the cap.

The replacement batteries that we installed both AGM (other, more expensive make) and FLA are functioning perfectly in all installations- we also know of many other distributors/installers that have had exactly the same depressing experience all across spain with this model of battery.

So basically, to not waste anyone's time, we know the problem is in the battery design. What I'm trying to find out is exactly what- hence me trying to draw on the experience in the forum.

BB. · May 2016

Yes, does sound like battery problems.

Just to clarify, no vent (no air passage), or no valve (one way air flow/over pressure relief valve).

I am not sure I understand which these caps are (no air passages, or open air passage).

If there are no air passages, I have seen batteries start to inflate like a balloon (the sides start bulging out when charging).

-Bill

Vic · May 2016

BB. said:

Yes, does sound like battery problems.

Just to clarify, no vent (no air passage), or no valve (one way air flow/over pressure relief valve).

I am not sure I understand which these caps are (no air passages, or open air passage).

If there are no air passages, I have seen batteries start to inflate like a balloon (the sides start bulging out when charging).

-Bill

Agree Bill, there is probably a semantics issue.

There does need to be some intentional venting device, otherwise, in an emergency condition, the battery will often eventually vent from the weakest point in any given battery. There simply, MUST be a venting device.

Ideally, there would be a pressure valve venting device.

But, this is probably too fine a distinction.

lazza, would guess that most of us here have never dissected any of their Renewable Energy system batteries.

If you are very serious, you might have to hire some Lab or consultant, skilled in the art of batteries, to analyze some of these failed batteries, and generate a report of findings. It would be best, if any such expert has a well-known reputation. In the USA, this person might be called an Expert Witness in Court.

If there are many disappointed customers/distributors/installers, perhaps you all would have influence on asking for some compensation for any early failures, and so on.

Good Luck, Vic

zoneblue · June 2016

From what i have read an AGM battery that has no catalyst will fail in about 1- 2 years. When a catalyst is present the vent is set to allow the pressure to build up somewhat. The AGMs here dont have any kind of user removable cap.

mike95490 · June 2016

AFIK, VRLA batteries do not have removable caps, they are flat top cases and the vents are integral in the top.

They likely tried to stuff glass mat into the cells and add a regular cap. If some batteries got low, adding distilled water may recover them.

westbranch · June 2016

Au contraire:

AFIK, VRLA batteries do not have removable caps, they are flat top cases and the vents are integral in the top.

My first AGMs, an older Absolyte IIP, have removable caps, with an integral 'pad' of some porous material and NO catalyst,
my second set C&D's,have a removable cap with the caveat that removal VOIDS any Warranty......and the manufacturer does NOT recommend using a catalyst, ... which makes me believe that they already use a catalyst..

The Catalyst market is/was a big improvement a few years ago, selling each cap for $25 per cap or more depending on the maker and AH rating.

mike95490 · June 2016

Now I know different.

lazza · June 2016

HI Guys,

Thanks for your replies. Yes that is exactly what we plan to do. Get some laboratory tests to demonstrate that they have no valves- if additionally we can prove they are dangerous, that would be an added bonus to get compensation- but we'll see.

This is the first I've heard of catalysts required in the caps- i suppose that's not obligatory- but i'd have thought valves are- there surely must be some saftey regulations that require some kind of venting??

westbranch · June 2016

here is a little reading for you on VRLA's
http://www.battcon.com/PapersFinal2008/DeMarPaper2008PROOF_7.pdf

Vic · June 2016

westbranch said:

here is a little reading for you on VRLA's
http://www.battcon.com/PapersFinal2008/DeMarPaper2008PROOF_7.pdf

An interesting read. Thanks westbranch. Vic

vtmaps · June 2016

Vic said:

westbranch said:

here is a little reading for you on VRLA's
http://www.battcon.com/PapersFinal2008/DeMarPaper2008PROOF_7.pdf

An interesting read. Thanks westbranch. Vic

Whenever I want to read that paper, I go back in time and click on the link here.

--vtMaps

Vic · June 2016

vtmaps,

Thanks for that Link. Kind of forgot about that one. Thanks again, Vic

mike95490 · June 2016

This is what I've always heard in the past
" The Absolyte batteries are some of the best batteries you can get. I had a set that were 9 years old when I sold them 3 years ago and they are still working fine for the people I sold them to. The Absolytes are sealed and never need watering. Do not try to open them or you will ruin them."
And the cases of the airline transportable sealed AGM batteries have no knurled caps, the top is flat and must be pried loose to reveal the sealed caps below it.
So I guess there is a new breed of AGM that has a removable & resealable pressure valve/Cat cap, and I would suspect it is not air transportable.

westbranch · June 2016

Mike, I'll try to remember to get a snap of the caps on the old Absolyte....it took a special tool (needle nose pliers also worked) to unlock the cap as it had 2 little holes on the surface, to insert the tool into... 1/2 turn or so and them remove..

lazza · June 2016

HI- just to let you guys know that i've found the safety valve system. It's in the caps, there is a small rubber cap on top of the white part that only lets gases go one way in theory. It then passes through the small hole in between the red rubber seals above and through channels in the battery top to a small vent on the side which looked like part of the plastic molding, but in fact is a vent. (no flame arrestor present though)

So, all i can think to explain the catastrophic failures in these batteries, is that the red rubber seals dont do their job as seals properly. It's interesting that the main seal at the top of the thread doesnt rest completey on a lip for a perfect seal. It just rests on the sides in two places as you can see from one of the pictures. Thus under working pressure it could be that although the valve performs its job, the gases bypass the valve escaping through the first rubber seal ?

Makes our court case harder to prove that the batteries are faulty unfortunately, but we have to keep trying.

BB. · June 2016

OK--That makes sense on the cap... I don't think that the cap is a major issue unless the batteries are drying out (possibly, you can do a quick check on a scale between a new/good battery and a failed battery and see how much electrolyte is "gone").

I think your answer is going to be found with a knowledgeable laboratory analysis of the failed batteries. But, even then, it may be difficult to prove in court that the batteries have a design or manufacturing fault (is there contaminated materials, leaking battery case tops, or simply poor quality/design leads to a short cycle life, etc.).

The other way may be specific performance. If you have some written material from the reseller that these batteries will have 1,500 cycles when discharged to 50% and they only had 100 cycles--And similar batteries in your care do last >1,500 cycles--Then they did not meet their specifications. And it would be up to the mfg/reseller to "prove" that your systems/actions caused damage to their batteries (signs of over/under charging/excessive current with warped plates/etc.).

-Bill

Dave Angelini · June 2016

One in ten chance you will win (my guess) if they were a reputable company. You would need data logs for the whole period they were charging/discharging. Even a good lab would have trouble helping you because their findings can be supported by multiple causes.

As most everyone knows, AGM's are very sensitive to overvoltage, only use the best offgrid if you have to. Only buy from a large reputable dealer!

lazza · June 2016

Yes, that kind of trial would be great, but I imagine incredibly costly- we have a expert report on our installations that they are optimally designed and the only possible cause of failure is the batteries- confirmed by the fact that all the systems are working perfectly with the replacement batteries. May have to go with that report alone.

The batteries were manufactured in a supposedly "reputable" company, Monbat in Bulgaria- turns out last year or two, alot of companies have been having issues with their batteries- but this is hindsight. Impossible to know beforehand- it's like Toyota or Hyundai producing dodgy cars- you dont expect it.

Generic failure in AGM batteries- no safety valves??

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