Battery question

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mick

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I've had good (boat) battery advice before on this forum so I thought I'd ask a (car) battery question. Four year old car (Focus), original battery, normal use, battery consistently reads below 12volts on a reliable multimeter, engine always starts easily, no other problems. I've charged it using a CTEK charger and it reads 12.2v. Battery and charging system professionally checked - O.K. apparently. Are these voltage readings normal?
 
Sounds like a dead cell. I had one like that on an old Standard 8 (or 10), in fact there was a link soldered across the dead cell terminals. (This was in the days when each cell had external terminals.) The car started OK for a few years.

You would not get away with it on a diesel Focus. Mine was a bugger to start until I got a decent Varta battery from Tayna. The local garage always replaced the dud ones with another that did not last two years.
 
12.2 is pretty low. If measured on a rested battery, ie no charge or discharge for at least 12 hours it would be equivalent to only about half charged.

A fully charged battery and rested battery should read about 12.7 ish

However a battery in a modern car is always supplying a small amount of current so expect the volts to be very much lower than 12.7 except when recently taken off charge.

I'd check the meter I think esp if the engine always starts easily, even in the current cold weather.
 
I'm pretty sure there's something peculiar with the charging system of Ford Focuses and they require batteries that can handle a slightly higher voltage. I seem to recall that calcium (I think) batteries are needed for these cars. A standard battery will not handle the increased charge very well.
 
Wight Dawn said:
Sounds like a dead cell. I had one like that on an old Standard 8 (or 10), in fact there was a link soldered across the dead cell terminals. (This was in the days when each cell had external terminals.) The car started OK for a few years.

You would not get away with it on a diesel Focus. Mine was a bugger to start until I got a decent Varta battery from Tayna. The local garage always replaced the dud ones with another that did not last two years.
Click to expand...

I doubt it is a dead cell. The voltage reading of 12.2v on 5 cells would be equivalent to a rested voltage with 6 cells of 14.2 volts and that would be too high.
I think that the voltage reading of 12.2 is fine and you worry too much. The battery will eventually die sometime in the next few years. However my experience of new Ford batteries has been good in that they last for perhaps 6 years when the replacements last closer to 4 years. That is of course a generalisation.
If you are really worried buy a new battery especially if you can use the old battery in the boat. Or better fit an additional battery and VSR in the car. Ready for the battery failure. or just don't worry olewill
 
SWMBo's batt died on her Yaris two winters ago so i put a new one on, £35 from a not Halfords type car shop, but i put her old one on my boat as it was still reading 12.1 volts as a dedicated engine starter and its been fine even last winter in all the ice.
 
"I doubt it is a dead cell. The voltage reading of 12.2v on 5 cells would be equivalent to a rested voltage with 6 cells of 14.2 volts and that would be too high."

I have two 12 volt 85 Amp batteries for my boat (Yanmar 1 gm 10). Usually, fully charged, they are about 12.6 volts. However, the one I have at home has suddenly dropped to 10.56 volts, and even when re-charged (13 something in), dropped overnight to the same 10.56 volts. I guess each cell is just over 2 volts (12 volts), so one dead cell would be just over 2 volts, hence my 10.56. So I know my battery does have a dead cell. This one battery certainly would not start my engine!

Geoff
 
Mick, some of the Ford Focuses have two sizes of battery recommended. Ours is slightly older diesel version which could take either 75 or 100 AH sized batteries. The original Ford motorcraft battery was 100 AH and failed last year. In desperation the local garage ordered up a new el cheapo battery for me and the supplier sent a Varta Silver 75 AH for the same price. Worked perfectly through the snow last winter.

The calcium thing Saillorbill refers to is true in that since the batteries are sealed you can't top them up so the manufacturers have added lead/calcium to reduce the water loss.

The Barden battery guide would be worth studying:

http://www.barden-uk.com/PDFs/VARTA Catalogue 2008_2009.pdf

Pete
 
Do you mean 12.2V while on charge or after charge and a rest period?
If the former then something ain't right - maybe your voltmeter.
What does it read with the engine running?

12.2 fully charged OCV would imply a specific gravity of about 1.190. It should be (typically) 1.260. Have you topped it up very generously with water? Could just about explain it. S.g. of 1.260 gives a fully charged OCV of 12.6V (all at 20 deg).

Calcium is a bit of a red herring. Whether it's calcium (typ 0.1%) or low antimony (typ 1.5%) the alternator charging voltage should be around 14.0-14.4V. It's not so much calcium needing a higher voltage as the fact that the older high antimony (up to 10%) batteries that nobody makes now needed a lower voltage - 13.8 or less - so as not to gas too much and even go into thermal runaway.

"Sealed maintenance free" (not SLA/AGM) batteries are not all lead-calcium, many are lead-antimony, not sure which the Varta Silver (excellent batteries) is but antimony I think.

Calcium or antimony is just the alloying element used to give the plate grid strength. Silver is another alloying additive used in addition, not in place of. The active paste is made from lead only.
 
In the summer I was fitting an Mp3 player to my 6 year old diesel Jag, to find the voltage was 11.9 volts.The car has always started perfectly. As the battery is 6 years old I replaced with new, and after 4 months the new battery is reading 12.3 volt, way below what I expected, but the car starts perfectly.

The old battery charges and still holds charge and is currently running extractor fans ( old PC PSU fans) on a timeswitch and is connected to a 80 watt solar panel to keep it topped up. So far so good.

Perhaps we are being a touch sensitive about battery voltages?
 
Seems low.
I have a similar charger ( to be truthful, similar technology - mine is from Aldi :-( ) and it also tends to knock off early when charging. This is most pronounced when doing 6v motorbike batteries but that, as they say, is another tale.
I have a spare battery in the boot.
 
Just been round and checked them all

Car 1 EXIDE. Probably last used in September but battery charged from time to time. Only load is the clock. New 2005. 12.32 volts

Car 2 HALFORDS. Last used about a week ago. Clock and Radio Memory. New 2003. 12.35 volts

Car 3 WHATEVER RENAULT FIT. Last used Wednesday. Clock, radio and remote locking. Original 2004. 12.23 volts

Boat battery HALFORDS LEISURE. Charged from time to time since September. No load. New 2007. 12.68 volts

Note the boat battery is maintaining 12.7 volts, is the only one with no load at all .. but is the newest ........ pity the fecking case is leaking!
 
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pappaecho said:
In the summer I was fitting an Mp3 player to my 6 year old diesel Jag, to find the voltage was 11.9 volts.The car has always started perfectly. As the battery is 6 years old I replaced with new, and after 4 months the new battery is reading 12.3 volt, way below what I expected, but the car starts perfectly.

The old battery charges and still holds charge and is currently running extractor fans ( old PC PSU fans) on a timeswitch and is connected to a 80 watt solar panel to keep it topped up. So far so good.

Perhaps we are being a touch sensitive about battery voltages?
Click to expand...

There is some truth in that.

First, a vehicle battery in typical use is unlikely ever to be more than about 85% charged, it simply doesn't get enough charging time. If you don'tuse the car much it could be well down on that. That will itself lower the voltage.
Second, if it's a few years old (the OP's was 4 years), it will be degraded and that will lower the voltage again.
Third, starting an an engine in good condition only takes typically 5Ah or less. The battery can be very degraded in terms of Ah capacity and still give that short burst provided its internal resistance is still low enough. Grid corrosion is the main thing that raises internal resistance and modern batteries with improved materials are much better than they used to be for that.

However if you capacity test your old battery I bet it will be well down on Ah. It may have started the engine OK normally - but it probably wouldn't if you'd had parking lights on overnight.

You can't read too much into voltage except when a battery is in perfect condition, but if it's getting down towards 12 after fully charging with a mains charger (as indicated by the OP), it's near the end of life or something else is wrong.

Your new battery voltage looks a bit worrying unless you do very little mileage, in which case an occasional proper charge will extend its life.
 
mick said:
I've had good (boat) battery advice before on this forum so I thought I'd ask a (car) battery question. Four year old car (Focus), original battery, normal use, battery consistently reads below 12volts on a reliable multimeter, engine always starts easily, no other problems. I've charged it using a CTEK charger and it reads 12.2v. Battery and charging system professionally checked - O.K. apparently. Are these voltage readings normal?
Click to expand...

Even a dud battery may show over 12 volts under no load using a multimeter. So don't rely on a multi meter reading as a test. But if the battery has been professionally tested and pronounced okay, and if its performing okay, why worry?
My wifes 04 plate Ford KA had the original battery in it when we traded it in March 2011.
 
Hi Ashking, you have just revived a very old thread. I see you are located in India. The brands of batteries available there are probably different to the ones in the British Isles, where most of the contributors to this forum are based. Perhaps someone from the subcontinent will read this and give some advice, but be careful what you buy; I have seen, on a television documentary that in India, old batteries are dismantled and rebuilt in backstreet workshops.
 
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