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Knackered Battery?


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#1 monkey

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Posted 02 January 2018 - 03:34 PM

87 998cc City

So I know a lot of this has been covered before and I have had a search around, but here goes...

Iv has a sluggish starting problem for a while where the engine turns over really slowly. I assumed the battery was good as it was only changed around a year ago so I cleaned all earths and changed the starter relay but no change. Because of this issue I havent been using her much, yesterday I went to her after 6days of not driving her and she wouldnt start. As soon as I attached jump leads from the daily driver the engine span over super quick and started fine. Voltage at battery with engine running was 14.28v, left her ticking over for about 30mins. I turned the engine off and about 30mins later tested the voltage at the battery and it was 12.79v (fully charged?) i have then left it for 24hrs, retested voltage at the battery and its gone down to 12.39v. Would this suggest the battery is knackered? Whilst it is only a year old she doesnt get used much and when she does it all short journeys, so this may contribute to a short battery life?

Thanks in advance and sorry to go over old topics again :-(

#2 carbon

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Posted 02 January 2018 - 04:03 PM

30 minutes on tickover is not enough to charge up a low or almost flat battery. Also using a car on short journeys with lights/heater running does not give it a chance to recharge properly.

 

I would suggest taking the battery out and giving it a proper charge with a decent trickle charger (or charge in situ if the car is in a garage with mains power). The type of charger I have been using cost about £12 from Lidl, has been very reliable. Puts out about 3 to 4 amps, takes up to 12 hours to charge fully.

 

PS. 12.8V immediately after charging is normal. If you put the sidelights on for a few minutes you will probably see it drop (maybe 12.3V) and then recover slightly (maybe back to 12.4V) when the sidelights are switched off.



#3 monkey

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Posted 02 January 2018 - 04:23 PM

Sakura SS3630 Battery Charger, 6 Amp https://www.amazon.c...i_Yc7sAbM75940H

Would something like the above be ok? It says 6amp, never heard of the brand Sakura.

When I first turned the engine off the voltage was higher but I didnt note it down, just over 13v I believe - I flicked the key to quickly spin the starter then left it the 30mins and took the reading of 12.79v

#4 timmy850

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Posted 02 January 2018 - 11:00 PM

You could also take the car (or even just the battery) down to your local battery shop, they can test the battery using the proper gear and tell you if it's just short on charge or has a fault. 

 

I've got a Ctek trickle charger for mine, they are fine to leave connected during storage and will cycle the battery to preserve the life and keep it fully charged. 



#5 minimans

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Posted 03 January 2018 - 02:59 AM

Nothing in your voltage readings suggest the battery is knackered, however the only sure battery test is a load test. As suggested take the battery to your local auto parts shop or call around until you find one that will test your battery properly.



#6 monkey

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Posted 03 January 2018 - 08:04 AM

Hi guys, thanks for your input, it sounds like maybe I am making a mountain out of a molehill as far as the battery is concerned. I have ordered the charger I linked to above, so when that arrives ill give it a good 12hr charge and then see if it holds a full charge. I assumed maybe the battery was knackered due to the voltage drop over 12 hours, but in hindsight it probably wasn't fully charged in the first place!

 

Ill try a good charge, assuming it holds its charge ill see then put the battery back on the car and see if it helps with the charging issue.

 

Thanks again

 

Steve



#7 minimans

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Posted 03 January 2018 - 08:47 AM

A battery will always drop in voltage after charge, It's called surface charge, as it bleeds off the battery should stabilize at a voltage somewhere above 12v your 12.39 would be a good static voltage but does not indicate if the battery has problems under load which when you think about it it's the only bit that matters...................



#8 KernowCooper

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Posted 08 January 2018 - 09:41 PM

After being charged the battery voltage will drop as said above, do the test after 24hrs from fully charged and 12.65v is 100%, remember that a battery thats gone flat will never give 100% again, if your battery voltage keeps dropping then it indicates the battery is sulphated  and this can happen to a newish battery very quickly. In your case I would charge the battery fully with the charged you have on order, let it stand and monitor it over the next 5 days, If you see the voltage dropping as par the % remaining in the battery it indicates the battery is failing and time for a replacement. Its a fact that even new batteries not charged can fail in 12-18months, check yours is not under guarantee? or fit a bigger replacement battery.

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#9 phillrulz

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Posted 10 January 2018 - 10:07 PM

Can always take it to halfrauds and ask them to test it. But think we all know what they will say 

 

 

 

ALSO: The other-day my dads old car sat on the drive at least 5 years took the battery out at 4.5v Charged it for 24hour it revived. good enough to start the car first turn of the key so it could drive the 5metres on to the scrap flat bed RIP. 


Edited by phillrulz, 10 January 2018 - 10:12 PM.


#10 monkey

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Posted 14 January 2018 - 02:13 PM

Cheers for the replies guys, I thought I should update, I charged the battery for 12hrs with the charger i linked to above and its been working perfectly, starting on the button everyday. I think it is probably just a combination of short runs, and cold wet dark mornings putting stress on the battery. I only just saw your last post kernow, if the issu returns Ill follow your advice :-)




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