Are lead acid batteries made equal in quality.

[eveares]

I need to get two new 7ah 12V Lead Acid batteries for my 1000va Belkin UPS as they are shot after 3.5 years of use.

They clearly need replacing as the UPS just shuts of immediately on power loss and the batteries are very hot and slightly swollen out. Ones even resting around 6V. They are wired in series to give 24V @ 7ah.

The thing is though, are lead acid batteries all made equally as good. Thinking about picking two up from TLC/Yes Electrical. Just wondered how they compare to batteries of the same type and rating what cost twice as much?

Also, what brand is better out of Deta or Honeywell Security when it comes to Lead Acid batteries?

Regards: Elliott

 

[ericmark]

I have found the valve regulated lead acid battery either the gel or the glass fibre mat do not normally last more than 2 years when under 20 Ah. The larger ones can last well, got a pair on mothers mobility scooter now 10 years old, but the small ones be it an alarm or hedge cutter, or chair lift, rarely last over two years.

I do think likely down to chargers used. I would think an alarm or UPS where in the main just sit on stand-by the voltage for a 12 volt battery should be around 13.2 however found quite a few at 13.4, also it seems not being used also makes for shorter life, stair lift used every day by dad batteries lasted around 3.5 years, now used once in a blue moon by mother batteries fail after 2 years.

I got replacements from screwfix, think you need to buy from someone with a high turn over.

 

[JohnD]

the batteries are very hot and slightly swollen out.

I would be very suspicious of the charging voltage pattern.

In my burglar alarm, the SLA should get changed under contract at five years, but was missed and was in perfect condition at ten.

Yuasa have a good reputation.

p.s.
My commercial premises have a central emergency lighting pack with big batteries, given a one-hour test every month. IIRC the first battery failure was at about 20 years.

 

[bernardgreen]

Quality varies enormously. Stick to reputable suppliers and avoid low cost Internet sources.

I used 10 Ah and 7.5 Ah batteries from both Rapid Electronics and RS Components for the lighting at my daughter's wedding, most were bought new for the event but some were from February 2013 or before. These "old" batteries ( from Rapid. Brand Haze ) had not been cared for, some had been cycled a few times and some just left on the shelf but they all had capacity very close to the rated capacity after a re-charge .

 

[eveares]

I am ideally wanting to pick two up locally for £30 total. Any idea's?

The old brand of batteries was "Ultramax", can't remember where I sourced them from but it was online.

I would be very suspicious of the charging voltage pattern.

Well they have been fully drained and recharged a few times in the last few months.

 

[ericmark]

I have also found some old batteries which have not been charged for years spring back into life. Which is why I blame the chargers rather than the batteries for short life. I have removed the tops and valves (rubber cap) and added a few drops of water and they have also sprang back into life, again pointing to the charger being set too high.

I fitted a pair of these screwfix batteries to mothers stair lift, the old batteries I took home and they will power a small 12 volt bulb for hours, but will not deliver the current required by the chair lift without going under the voltage at which the stair lift switches off. I am sure if I was able to cycle the batteries a few times they would come up again.

However in a stair lift a real pain when they go as always parked at top of stairs at bottom there is an extending arm which blocks the hall when down, so you can bring the chair to bottom OK, then you can't get it back up. Winding by hand really takes and age, so ended up pushing the chair while powering to reduce load and inched it up 6" at a time. So not worth playing with old batteries.

The write up for the glass mat valve regulated lead acid talks about the problem of the acid concentrating at the bottom of the battery, with a normal lead acid the liquid naturally circulates but with the glass mat that's not the case. But at £18.45 is it really worth messing with?

Back in the 1980's I came across some larger VRLA fitted to Chev cars, these were to be fair far better than the normal lead acid, they behaved very like Ni/iron batteries in that they would give full power until nearly the last, no slowly cranking slower and slower it cranked full speed to last then died. Even in the heat of the Sahara desert they seemed to do well. Same with the larger batteries fitted to mobility scooters. But the small ones fitted to alarms and chair lifts seem to dry out.

Stair lift and mobility scooter got around the same time, scooter on original batteries, stair lift on fourth set now. I have considered fitting a diode to reduce charge voltage I am sure it's the chargers which are simply set too high for intermittent use.

 

[bernardgreen]

Eric

Have you thought of fitting a "jump lead" socket to the stair lift.

A four pin plug (1) battery + (2) battery - (3) chair + and (4) chair - with a free socket linking (1)-(3) and (2)-(4) for normal use.

The emergency battery with a lead and socket with e battery + on (3) and - on (4). Socket on the emergency lead so there are no exposed pins with 12 volts on them. The perfect solution would use a mix of male and female contacts.

 

[ericmark]

Had the battery drill not also failed I could have used that to return the chair home. But I hope with new batteries it will be a while before I need to do it again. I was surprised, I thought the batteries were for back-up, but it transpired the batteries work the chair which is then re-charged at any of the three charge points, one at bottom which can't really be used, one on first bend, and one at top. Even the leg is battery operated, and the fixed controls are also battery operated RF link to the chair. I can see point that in a power cut chair still works, but in real terms there have been more 24 volt DC power cuts than 230 volt AC so the thinking is rather flawed. Not even any kind of battery meter so first one knows is chair has failed.

Lucky I was using it to move stuff other than my mother on the stairs, to have an amputee stuck half way would be fire brigade job, idea of getting between her real and false leg to wind it down manually does not bare thinking about.

 

[eveares]

Had the battery drill not also failed I could have used that to return the chair home.

Mains hammer drill? (with the hammer function turned off of course.)

to have an amputee stuck half way would be fire brigade job

I take it in such a scenario there is not room to safely carry her down/up from the middle.

 

[ericmark]

She may be 91 but not what I would call frail she is a fair weight. But really only talked about it because of the batteries.

My son worked for an alarm company and he said also how to get much more than two years out of small VRLA is rare. And yes they did try different makes, be it 2.3 years or 2.8 years it is hard to tell if that is due to make of battery or just natural variations. Because one odd battery lasts 5 years does not mean that was a good make, it may not have even been a good battery, it could have just as easy been the charger was set 0.2 volts lower than normal.

 

[JohnD]

I would be very suspicious of the charging voltage pattern.

Well they have been fully drained and recharged a few times in the last few months.

I meant, "intelligent" chargers are supposed to charge up to a target, then reduce to a "float" voltage, at which hardly any current is taken, just to keep the battery topped up. If the batteries get hot, and bulge or gas, they are overcharged.

The time, current and voltage pattern varies with battery type. You will remember with old trickle chargers for cars, you had to charge overnight, then take off charge, not leave them connected for long periods, but you can now get much more expensive chargers to be used with vehicles laid up over winter, some of them include a "conditioning" cycle. A UPS is going to be connected for very long periods.

Telephone exchanges have stand-by batteries in great numbers but I don't know what life they expect.

 

[Adam_151]

You will remember with old trickle chargers for cars, you had to charge overnight, then take off charge, not leave them connected for long periods

I did an insurance job for a chap once, who had a big posh house (six bedrooms each with en-suite, about four livings rooms, big fountain in the driveway that you drive around like a mini roundabout, etc, etc)

The garage was massive, all plastered, painted, tiled floor (like they have in car showrooms). Anyway this chap had put a car battery on charge, and forgot all about it, until he came home one sunday after a trip out, about 3 weeks later and saw smoke coming out around the garage door. The outcome was that the battery had slowly been boiling dry and then had set on fire

 

[bernardgreen]

The old "fish tank" lead acid cells in telephone exchanges were planned to have a 10 year life span. Originally the exchange was supplied from one of two batteries. The battery supplying the exchange could not have the charger connected due to the mains hum the charger would put onto the supply. While one battery was running the exchange the other would be on charge. If a cell did start to degrade it was then a relatively simple process of drain out the acid, remove the plates, wash out the tank, install new plates and fill with fresh acid. I seem to recall the repaired cell would be conditioned on its own before being connected back into the battery.

Voltage regulation involved counter cells. This is one description based on USA exchange technology

Counter Cells

Counter-E.M.F. cells are used in telephone power plants to reduce voltage for a tap or feeder and also to control the voltage on the battery bus bar while charging. Their function is similar to that of a series resistor except that the voltage drop in a countercell averages 2.to 2-1/2 volts per cell and varies little with changes in current.

The cell container or jar is filled with an alkaline solution over which there is a layer of neutral mineral oil. Plates are suspended in this solution and connected in series with the battery. The voltage drop in the cell is the voltage expended in forcing the current from one group of plates through the solution to the other plates. The plates are all of the same material (nickel or stainless steel which contains nickel) so that the plates can be connected to either polarity. There is practically no storage of charge in the plates so that cells in a working circuit can be shorted with safety. The disadvantage of their use lies in the fact that energy is dissipated in the counter cells, produces heat and the decomposition of water, which results in a large amount of gassing. The gases are hydrogen and oxygen which form an explosive mixture. There has been a number of explosions of counter cells in the Bell System and in a few cases have resulted in physical injuries. Today the use of these cells are not looked upon favorably and their use is decreasing.

 

[JohnD]

I'm surprised these batteries have such a short life. All the car batteries I've replaced recently have lasted over ten years. One was a Varta silver-top rebranded with the car maker's name, at least one of the others was made by Varta, so I've bought them. Surely car batteries have a harder life, and are more likely to be neglected, than SLAs in an indoor device? Unless the device has a badly designed charging circuit?

 

[eveares]

Well this 7ah 12v Lead Acid battery from Yuasa is supposed to have up to a 10 year life span: http://www.hardwarexpress.co.uk/rew45-12-yuasa-rechargeable-battery-3209-p.asp

Data Sheet: http://docs-europe.electrocomponents.com/webdocs/07bd/0900766b807bd5d3.pdf