UPS battery life

I have a battery I bought for an APC UPS about 4 years ago. I bought 2, and used one immediately. I kept the other on the side as I have several UPS's that use basically the same battery. Of course, over time, it has discharged itself. I measured about 4.3V instead of the normal 12-13V. I put it in a spare UPS, which immedialy complains if I try to turn it on. Luckily, the UPS charges even when it is off, but slowly. I measured about 15mA initially, and after about 36 hours, about 7.5mA. It is currently up to about 10.7V.

How much damage do you think was done to the battery? I know it will lose some capacity.

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Reply to
Andrew Rossmann
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Andy, It sounds like it may be at least partially sulphated now. I would turn on the UPS and put a heavier charge rate into it, or, if that is not possible, then charge it with an external 12V charger. If it does take a charge, then cycle it a couple of times [discharge/ charge] and then measure how it performs in the UPS under moderate load. You may have caught it in time, or it may be too far gone. One really good indicator is if the batttery case has bulged so that there is a distinct bulge in the sides and ends between the cell separators, then the battery is definitely 'toast'.

Neil S.

Reply to
nesesu

There's a reason alarm companies change the sealed lead acid batteries annually. Typical life on them is about

2 years. 4 years on the shelf is well, not good.

Keeping them charged up at all times is the only way to keep them (or any lead cell) happy and useful.

Jeff

Reply to
Jeffrey Angus

Next time you buy a spare battery to save for later, buy a dry-charged battery with the acid in a separate bottle/applicator.

The Varta motorcycle battery I bought before the UK VAT increase came with a DIY filling kit so I could store it till I need it, with a bit of shopping around you should be able to find a DIY filling kit SLA.

Reply to
Ian Field

The battery is likely 'toast' now, I'd suggest replacing it. If you have a compatible desulfating charger you could try desulfating it, but I suspect there is little or no hope.

Reply to
PeterD

The battery is physically in good condition. No bulging or anything like that. Given how low the charge rate is, it'll probably take another day or two to fully charge. I've seen this battery for about $14 at Amazon, so it's not that expensive (the shipping is almost as much!) If I can get it to the point where the UPS doesn't scream 'replace battery', I can then test it to see how well it works.

I don't have any other real charging source, or at least something I'd consider safe. The only 12V source I have is an old Radio Shack regulated 12V@2.5A supply, or some wall warts. The charging rate is low, but I assume it's probably safer and better for the battery than trying to charge it quickly?

This all came to a head due to a power outage on Friday. The battery in one UPS (APC Back UPS 725 ES, 7 AH battery, probably 6+ years old) only lasted about 5 minutes powering a cable DVR, VCR, and an RF modulator. I wanted to replace it, but this battery was too weak. Another UPS (same as the other) running my modem and router ran for an hour before I decided to turn it off.

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Reply to
Andrew Rossmann

It sounds as if the battery has become badly sulphated. This is not uncommon if you let a lead-acid battery sit around un-used... the lead plates have become coated with a layer of lead sulphate, in a crystalline form which is both insulating, and difficult to convert back to a soluble form. The battery now looks pretty much like an open circuit to the UPS, as it has a very high resistance, and it will not accept a charge efficiently from the recharging circuit.

To keep this from happening (in the future) it's best to keep the battery fully charged, via a "float-charge" mechanism at just the right voltage (which depends somewhat on the temperature).

There are techniques which can be used to de-sulphate a battery and restore it to at least some degree of usefulness. The techniques vary in detail, but usually involve applying a higher voltage to the battery (with a careful limit on the amount of current available!) to break down the sulphate crystals and allow them to re-dissolve. This is sometimes done via a "pulser" (which generates short high-voltage pulses) and sometimes through a dedicated high-voltage supply.

Whether a badly sulphated battery can ever be returned to a substantial fraction of its original capacity seems to be a somewhat controversial question... some say yes, some say no. It may depend a lot on the specifics of the battery type and the degree of sulphation.

Your best bet is probably to just buy a fresh battery, when you know you need it for one of your USP systems... and check the date code on the new battery before you buy it to make sure it's really fresh and hasn't been sitting on a shelf for several years!

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Reply to
Dave Platt

=A0 =A0 =A0 =A0 =A0 =A0 =A0 AE6EO

r

Usually you need to buy the battery a couple of days BEFORE you discover you need it :-)

At work we had a very large UPS that used 600V of gel-cell 12V batteries each about the size of a largish car battery. In the 15 years or so that it was in use, there were, perhaps, 5 power failures and the UPS failed every time even though all the routine maintenance and testing was observed. Other than the first time when it was only a month or so old and the inverter blew up [linerally] all the rest of the failures were due to battery failure.

Neil S.

Reply to
nesesu

You can also lower the specific gravity of the cells to prolong life. Of course, only applies to *wet* cells.

Reply to
D Yuniskis

I say maybe. One trick that I've tried, that has worked with lightly to moderately sulfated batteries, is to clamp it in a paint shaker and shake along the axis of the plates. If you can't find a paint shaker, I've used a Sawzall with a custom shaker attachment.

Anything that reciprocates will work. The idea is to get the gel or liquid electrolyte to slosh around, hopefully causing the lead sulphate coating to break off and fall to the bottom. Unfortunately, if the plates are badly corroded, instead of the lead sulfate falling off, the plates will crumble. As a side benefit, you'll get quite an arm massage with a heavy battery. My batting average is about 50% so this is not a reliable method. Still, it has produced a few miraculous battery recoveries.

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Reply to
Jeff Liebermann

There are betters uses of a sawzall.

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Jeff

Reply to
Jeffrey Angus

Per nesesu:

This begs a question that's been bugging me for years: why doesn't somebody make a UPS that hooks up to a 12-v non-vented automobile battery?

Automobile batteries are available at many different price/quality points, they're pretty much a universal standard, the capacity is there in spades, public knowledge about maintaining/replacing them is widespread, and push-comes-to-shove in an extended outage, the battery in somebody's car can be swapped in for a few more hours working time.

I guess there has tb a reason... but what?

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PeteCresswell
Reply to
(PeteCresswell)

Short term vs long term capacity.

Automotive batteries really don't like being a long term power source. You're actually better off getting a Marine battery for that.

And you probably do NOT want "joe Consumer" dicking about with a the current capacity (and capacity for impressive flames and smoke) when he hooks it up wrong or drops a wrench across the terminals.

Jeff

Reply to
Jeffrey Angus

We had a distant radio-communications site that had grid power. It needed battery backup as the grid certainly didn't provide the 100% availability that we required of the radio systems. Because of the distance and the cost of maintenance trips, it was visited annually (unless a failure occurred).

After some analysis it was determined that the best backup battery option was the standard "maintenance-free" auto battery, replaced each year. More expensive batteries didn't stack up economically, and these also were donated into auto use after retrieval, where they gave additional service.

Reply to
who where

Automotive batteries are not well suited to long, continous drains that the UPS would require. Using a deep cycle battery (such as a trolling battery, or an RV battery, would work, but not optimal.)

Reply to
PeterD

Per PeterD:

Is that to say with the first power outage and running the battery to near-exhaustion (assuming there is a means to control how far down it goes) that the battery would be damaged?

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PeteCresswell
Reply to
(PeteCresswell)

In a word, possibly.

The construction of the plates in automotive vs marine (RV) batteries are different. The Automotive battery is designed to deliver large amount so f current for short periods of time.

The marine batteries are designed to for a long term steady and considerably lower) current draw.

Jeff

Reply to
Jeffrey Angus

The 12V batteries made for CATV UPS duty are made for high current and deep cycle loads.

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Reply to
Michael A. Terrell

A charged but unused SLA should retain its charge for months. The battery powered cars the grandkids love (got them on freecycle, not new at $300 each) have 12 volt 10AH SLA batteries and typically get charged twice a year (when the grandkids are here). I use a Black & Decker charger that does 1 or2 amp charging (switch selected) and the

1 amp charge works well. The B&D charger is "smarter" than the original charger which comes with a "do not charge more than X hours" warning. Many UPS chargers are in the same category - they do a fast charge to quickly replenish the battery after use, but there is no "smart" monitoring. I've seen several different brands of small UPS (300 watts or so) kill batteries in a year or less - even if unused. The charging circuit simply cooks the battery.

Forget about using a UPS to charge a battery. Instead, buy a real charger which won't destroy a bettery even if it's left on charge all the time. For most UPS batteries, I would recommend the Black & Decker Smart Battery Maintainer. It uses a switch mode power supply and has LEDs for "charging" and "charge complete". The charger is $22 at amazon.com

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and I've seen it for about $20 at Target and Walmart. If you can find the older version with the 1amp/2amp charge level switch, it's even better on the smaller batteries.

Keep an SLA battery properly charged and it will last a very long time. The electric cars are typically driven until they no longer move, so the batteries get a full discharge at relatively high current (5 amps on level driveway; 15 amps uphill - more if two kids in one car). These batteries have been in service two years and seem to have close to their original capacity.

John

Reply to
news

I think the reason for the long battery life in this case, is more likely due to the quality of the batteries you're using. What is the brand name and model number of the batteries?

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Reply to
Wild_Bill

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