Lead acid battery mystery.

On 18/11/2017 21:34, T i m wrote:

That has been my point in this thread. You don't expect a good battery to gas when charged by a well suitably controlled charger.
Batteries can go without topping up for years. Hence the OP's experience is out of kilter with mine.
I can assure you it isn't due to recombination catalysts.
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I'm not sure that is true. I've just bought 3 traction / cyclic spec 'gel' batteries (not wet / flooded) that are VRLA and gas whilst being charged during the balance phase (you can hear them doing so quite clearly).
It is good that stationary flooded cells gas to some degree when in the last phase of their charge to prevent electrolyte (and therefore charge) 'stratification' as the rising bubbles help mix the electrolyte.

I agree. My EV didn't have recombination cell caps and so did require regular distilled water adding and when left unattended for a long time, most of the cells dried out to some degree. ;-(

Cells do gas not only when charged but when being discharged and that includes when they are self-discharging. If the OP's battery is only 25% of it's original capacity and whilst it is still functioning, I wonder if it's self-discharging more than the other batteries he's comparing it with? <shrug>
Cheers, T i m
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On 18/11/2017 22:20, T i m wrote:

Complex charge regimes usually have an equalisation charge phase where the intention is to 'overcharge' the battery so it gasses, hopefully undoing some of the sulfation and mixing the electrolyte. It's done as a separate process to absorption and float charging.

Given the quantities of water the OP says the battery has been consuming, even a complete self-discharge wouldn't cause 50ml to disappear from each cell.
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<snip> >> It is good that stationary flooded cells gas to some degree when in

As do the most basic transformer based chargers.

That would be a big *hope* IMHO.

Yes, that is a positive side effect of 'overcharge' gassing.

Yes, if you break down the phases logically with say a 'Smart' charger but still happens with a basic charger (to varying degrees, depending on the terminal battery voltage and the charge / current and voltage etc), during the end of the absorption phase (the last 10% of the charge).
<snip> >> Cells do gas not only when charged but when being discharged and that

I agree. The 8 x Crompton 6V x 200Ah traction monoblocks I was running in the EV would take that (each) and more if I left the checks for a bit too long (weeks rather than days) but I'm not sure even they would lose that (each) when the car was not being used. However, when left for a couple of years unused, even these large and fairly new (compared to the OP's battery) batteries lost enough electrolyte to expose the plates. If I checked them again now, all the cells are probably bone dry. ;-(
Now, that is either from evaporation or the plastic battery cases being gas-permeable to some degree (as is much plastic) and it's (the water) simply leaving as gas (H2O)?
Cheers, T i m
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On 18/11/2017 21:52, Fredxxx wrote:

*My* point is that while I understand perfectly that overcharged batteries will gas during (over) charging, mine appears to be losing electrolyte while *discharging*.
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newshound wrote:

Is this battery in open in bright sun oran enclosure that gets very hot?
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On 17/11/2017 23:24, FMurtz wrote:

No.
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On Fri, 17 Nov 2017 19:24:05 +0000, newshound wrote:
====snip===

Even assuming a capacity of 20AH, that's still only 25% of its original capacity.

Quite frankly, I think, at a mere 25% of capacity, the battery is well and truly "Shagged". I used to run two banks of 'revived' ex-pabx batteries[1] for about a decade before the cells finally became too thirsty to justify the cost of distilled water and the energy to keep them charged.
Although there was plenty of space beneath the plates, the paste in the plate grid structure had eventually disintegrated enough to form a significant layer of debris in the bottom of the cells where it could no longer provide its original function as plate anode material and, if not actually shorting the plates, it was certainly increasing the self discharge leakage rate (hence their thirstyness). I'd had a good ten years worth of service out of 'My Freeby' by then so finally decided to call it a day and weighed them in for scrap (along with a collection of similarly buggered SLAs and car batteries).
One thing to note with SLI batteries is that they're totally unsuited to use as UPS battery packs. It took 3 expensive lessons before I finally realised this. Mind you the first lesson was over ten years prior to the last two and only involved a single car battery connected to a 4A rated 13.8v CB radio mains PSU rather than the strings of 4 used with an APC SmartUPS2000 just a few years ago.
It seems that the continuous float charging 24/7 at 13.8v per car battery is what does them in after just 6 months or so of UPS service.
When used for their intended purpose (Starting Lighting Ignition), they thrive quite happily on their regimen of 14.2v intermittent charging and brief bursts of 100 plus amps starting loads along with the various accelerations associated with accelerating/braking and sideways G forces generated when negotiating corners and tight bends. It seems the 'rough mechanical handling' keeps the electrolyte nicely stirred up and homogenised preventing a deleterious density gradient in the electrolyte that otherwise builds up when wet cell batteries are used in a fixed location.
I reckon there was still more than 50% capacity in those car batteries by the time they became a maintenance liability and an unnecessary drain of charging power demand on the UPS. I have a theory that by sacrificing some some 5 or 10 percent of usable capacity by reducing the float charging voltage to 13.5v per car battery instead of the "standard 13.8v" normally used by APC UPSes, I might be able to get a better than 5 year service life. However, I haven't had the heart to put this to the test so it remains just a theory.
Getting back to your 'battery mystery', I'd say you're simply dealing with a battery that's long gone past its Best Before Date and is well and truly ready to be weighed in.
[1] When I discovered them in a decommissioned PABX, the battery had been disassembled into individual 125AH Tungstone cells and simply left standing for Ghod knows how many years. I picked the best 12 cells out of the 25 that had been left in a completely discharged state to haul back to my basement radio shack and connected each one to a basic 4A 12v battery charger via a current limiting 21W 12v indicator lamp until the almost pure water finally became reactivated with the electrode bound acid and the lamp started to glow before rigging a string of 6 at a time to let me connect them directly to the battery charger (doing this for two bank's worth).
Having revived them sufficiently to be charged as 12v batteries in the conventional way, I then rigged up a dummy load made up of three 0.3 ohm 100W resistors in series and boiled a few bucket's worth of water discharging them after each charge or reverse charging cycle until I was satisfied I'd restored them to as good a state as I could. It seemed I'd managed to get the capacity of each bank to circa 100AH at the 200 hour discharge rate - just over a week's worth running the 1.05A load from my VHF packet radio station setup.
--
Johnny B Good

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On 18/11/2017 01:56, Johnny B Good wrote:

Yes it is certainly shagged from an automotive viewpoint, but it gives me a month or so of "free" lighting at the stables. And of course unlike a UPS this isn't in any way a critical application, I normally have a spare ready to go.
<interesting stuff snipped>
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On Sat, 18 Nov 2017 01:56:26 GMT, Johnny B Good wrote:

APC "Smart" UPS's do cook their batteries. I only have a little one (750 VA) and it used to kill a pair of 12 V 7 AHr SLA's in 3 to 4 years.
The last failure was of the "What's that funny smell?" "Seems to be under the desk" "Ouch the UPS is rather hot":
https://www.flickr.com/photos/allsorts-60/16591022171
I then reduced the charge voltage and fitted a fan. UPS now reports around 30C internal temperature instead of the 40 odd before. This was in Mar 2014, We've had a few short mains glitches recently that the UPS covered, previously that sort of thing would have alerted me to kanckered batteries. Guess I need to give it a real test though, may be later.
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Cheers
Dave.
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On 19/11/2017 11:08, Dave Liquorice wrote:

Voltage is everything in charging a Lead Acid battery. Also, the higher the temperature the lower the ideal float charge voltage.
Anything more than 13.8V continuously applied is going to shorten the life of the battery.
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On Sun, 19 Nov 2017 12:31:09 +0000, Fredxxx wrote:

Some ought to tell APC. I dug out the datasheet for the batteries, the charge voltage was way above what it should be for the temperature of the batteries, for bulk rate let alone float!
Not that APC UPS chargers have bulk and float rates...
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Dave.
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APC are well-known for overcharging their batteries.
--
Today is Prickle-Prickle, the 32nd day of The Aftermath in the YOLD 3183
Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.
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Huge wrote:

People are also well-known for stuffing UPSes into tiny, unventilated places, then wondering why they all die in August.
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On Mon, 20 Nov 2017 10:32:56 +0000, Andy Burns wrote:

Yes, there is that factor too but, in my case, that can't explain the short life of SLAs and the even briefer life of two sets of cheap 36AH SLI batteries with the APC SmartUPS2000 acquired 2nd hand without a battery module (it's a split design and I only got hold of the inverter half sans battery case). The unit was set up in my basement shack, wired up to a set of four 12v SLAs in parallel with a set of four car batteries on the shelving below the UPS itself. The basement temperature rarely got above 18 deg C in summer and no lower than 8 to 10 deg C in winter.
Excessive temperatures are a proven deleterious stress on batteries of every type, primary and secondary cell types alike but is even more so with LA batteries subjected to an unremitting constant voltage float charging regimen. However, in my case it seems an unremitting 13.8v per 12v SLA and/or car battery alone was sufficient of itself to shorten battery service life. Excess temperature simply didn't apply in this case.
--
Johnny B Good

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On Mon, 20 Nov 2017 10:04:41 +0000, Huge wrote:

As well as overcharging *for* their batteries. :-(
In my limited experience of other, admittedly old brands of UPSes, the use of 13.8v per 12v battery pack was a universal practice. Today, I would hope a more intelligent charging scheme other than utilising the dumb constant 13.8 volt charging of SLAs is being used with the current crop of UPSes.
Although the likes of SmartUPS2000s and SmartUPS700s have extremely complex circuitry with microprocessor control of the sinewave inverter and its mains conditioning for over/undervolt events as well as dropouts, the battery charging circuits are about as basic as you can get (essentially a constant voltage supply).
It seems there's ample opportunity to improve on the basic battery charging management system of old with today's modern UPS kit. Whether an extra percent or two of the total manufacturing cost has been diverted to battery management with modern commodity UPSes to improve battery life or not, is something I'm not aware of since I've not shopped for new UPS kit ever.
It might pay me to check out the adverts for new UPSes to see whether any models are boasting of such improved battery care. I might get a hint as to whether reducing the classic 13.8v setting to a mere 13.5v would be the best way to go with my existing UPSes.
My experience with charging a 2nd hand 12AH SLA just once a year to maintain it in good condition by leaving to sit at its 12.7 volt resting voltage for over 11 months of the year, rather implies that a setting of 13.5v per 12v SLA would provide an improvement with just a small reduction in autonomy compared to a brand new, not yet shagged, battery that's slowly dying a death from being relentlessly subjected to the full 13.8 volts typically used by APC and others to maximise their advertised autonomy times on a brand new set of not yet shagged out batteries. It pays to keep in mind that advertising is the art of lying by omission.
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Johnny B Good

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Dave Liquorice wrote:

They can but not always. I can't help feeling they would help themselves if they ran the fan at low speed to increase airflow, even when there wasn't a mains problem.

A couple of years ago I posted a very similar photo of a Yuasa Y7 battery bulging after being used in an APC UPS
<
http://adslpipe.co.uk/photos/APC_UPS_battery.jpg

However the Y7 range are designed as alarm panel batteries, they produce NP7 batteries for UPS type applications.

I found the "secret" commands to adjust the float voltage (perhaps with hints from you or someone else here) and set out to adjust mine, only to find they were already bang-on.

As noted above, mine has a fan, but only uses it when it's covering a mains problem. Quite annoyingly it runs it for the daily spikes of a couple of seconds around midnight when "something" at the substation adjusts for over-voltage.
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On Sun, 19 Nov 2017 13:44:55 +0000, Andy Burns wrote:

My little one doesn't come with a fan. I hi-jacked the SNMP(?) card slot space and fitted a PC slot exhaust fan along with a speed controller.

Complain to your DNO. Ours (Electricity North West) takes complaints about the supply quite seriously, especially if you have data to back up the complaint. A regulator shouldn't spike as it changes and "around midnight" (*) strikes me as a bit odd as well. I wouldn't expect load variation to be that consistent, weekday/weekend being different at the very least.
(*) 2359 +/- 20 mins?
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Dave Liquorice wrote:

OK, it's not a spike, rather the times of day that the UPS goes into and out of buck mode, due to over voltage.

I plotted a chart in a spreadsheet of the time of day the overvoltage starts and ends over the last year, the main periods are roughly 6am to 9am and 9am to midnight. I didn't look at weekday/weekend variations.
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wrote:

When I was a datacomms guy we had some X.25 kit in a remote site that seemed to be regularly 'locking up', roughly the same time each Friday.
Long short, we put a mains voltage monitor on it and found a large spike on the cabinet PSU and that coincided to when the cleaners came in and plugged 'Henry' into the cabinet power strip. ;-(
Cheers, T i m
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