Worn battery or too many short journeys?

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Hi, just a quick one to check my reasoning.
Mother's car wouldn't start after sitting for a few days, battery showing about 11v on my test meter. Jump started it, disconnected jump leads and re-checked volts with engine running, now showing 14.5v. Gave it a reasonable run for about 45 mins (at night so with lights on), then stopped it for a bit. It started ok then I drive it another 15 mins. Tested battery again with engine off and it's showing 12.2v.
My reasoning says the alternator is charging ok, so it should have more charge than 12v after a reasonable run, therefore the battery is on it's last legs.
The car doesn't get used much, and only mostly for short 5 min trips.
What's your concensus folks - battery, or too many short runs and not enough time for it to charge?
BTW the same happened last winter after it had sat a few days. It's an 06 plate Focus 1.6 petrol auto with about 50k miles.
 
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New battery time Alan - I would guess its the original?
John :)
Thanks for the reply John.
When it didn't start last year I checked and found a receipt for a new battery, IIRC it was from Europarts, and about 1.5 years from then, so probably 2.5 years ago now. I'd need to check again to be sure but it might be in guarantee. Any idea how the guarantee works, ie give them the battery and wait a fortnight til they decide whether it's faulty etc?
Or do I just bite the bullet and buy a new one? Europarts have a £78 Bosch for £59 at the mo.
Thanks
Alan
 
I'll stick my neck out and say that 2.5 yrs isn't really old for a battery these days, however if the battery has been allowed to go flat just through lack of use then it could well have had it.....Obviously some car systems are always live, causing some slight drain.
The only thing I can suggest is to fully charge the battery and then disconnect it - reconnecting the thing when it's time to use the car. However, you'll lose the radio, clock, et al which is a bit of a bore.
If you have the receipt I'm sure the battery will be replaced.
One more test if you feel like it.....with the battery charged, check the voltage on cranking - it shouldn't drop below 11v, ideally.
John :)
 
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Thanks again John, I'll dig out the receipt and see how old it is first.
 
got start stop by chance?

The batteries tend to knack er quickly.

I'm on my 3rd in my Punto and this is the 3rd year I have owned it.
 
It depends on their use, as John says. Running them flat not many times will kill them, providing they are kept fully charged which a healthy charging system will do they should last 5 years or more but you could have something discharging it when parked. If you have a multimeter, remove the + battery lead when it been parked for a few minutes and connect the meter on the 'amps' range, + connection to the battery and - to the lead, it should read less then 50ma if much more you have something draining it.

Peter
 
Thanks for the further replies guys.
check the voltage on cranking - it shouldn't drop below 11v, ideally.
I put the meter back on it last night after it sat for about 3 hours, it showed 12.2v. Kept it on while the OH started it and I'm almost certain it went to 9.something volts for a millisecond before levelling around 11v.
got start stop by chance?
No mate, no start/stop. It's got auto lights and wipers but she is aware and always switches everything off before getting out. She also believes that turning the heater temp knob to cold helps lol.
remove the + battery lead when it been parked for a few minutes and connect the meter on the 'amps' range, + connection to the battery and - to the lead, it should read less then 50ma if much more you have something draining it.
I did the old-school version of that test, ie looked for a spark when tapping the lead onto the battery. There was virtually nothing so I'm pretty certain there's no drain.

I checked the battery again this morning, it's still at 12.2v.
It turns out she kept the AA patrolman's printout from the last time, 5th Jan 2015, which showed low battery voltage, and cranking amps at 110 where it should be 460, and no drain. The last line said "replace battery". I spoke to Europarts this morning and took the battery in for them to test. Their machine showed charge of 12.3v, and showed cranking at 360. This, apparently, is good and they couldn't replace it under warranty. They recommended charging it and refitting.
Decided to get a new (heavier rated) Bosch battery, which showed 12.5v off the shelf. After a 10 min drive it showed 12.8v. Hopefully it's now cured for a while.

Thanks again for your help:)
 
I would think that should cure it. I wouldn't rely on what the AA say, or at least the garages they send out. We visited friends in Cornwall a few weeks ago and I left the lights on parked at the bottom of a steep slope. They came out fairly quickly but wanted to sell me a new battery, he put his meter on it and it was showing 13.8v with the engine running, I said I would check the alternator when I got home which I did, the battery read 14.4 volts with my Fluke meter. Either he was trying a con or his meter wasn't any good.

Peter
 
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