Battery Help

[lewisheywood]

So a new headunit I installed was faulty and drained battery flat, friend jumped it and he accidentally put the terminals on the wrong way round on his car so when I put them on mine it sparked quite bad.

Charged the battery over night, started the car, let it idle for an hour to charge, drove to work turned it off. Turned it back on again to check and yet again battery flat.

I'm guessing something was fried (like the alternator), dead battery or fuse blown ???

Anyone able to help, need the car for work and garage can't take it in until next week.

Thanks

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[Cuprabob]

If the alternator wasn't charging the battery light would be on. You can double check by measuring the voltage across the battery with the car idling. It should be in the region of 13.8 - 14.4V.

It could just be that the battered is fecked and not holding charge. If you charged it over night then even if it wasn't charging in the car it should still have enough charge to start the car a couple of times, especially as it's not too cold at the moment.

[lewisheywood]

Thanks for the response Cuprabob,

I need to get my hands on a multi meter but I have a USB charger that displays the voltage and that showed around 13.8 , not sure if that's anything to go by.

I had the same thought after posting. Was on charge for at least 11 hours. My old MK4 golf would last 3 days when charged over night with no working alternator. Fingers crossed it is the battery then.

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[Cuprabob]

Based on that voltage displayed on your USB charger, it looks as if your alternator is working OK.

[Tom1964]

My battery went down all of a sudden a week after buying the car. There was no indication before it happened. Had the battery tested at my local battery supplier who insisted it was indeed the battery. Most likely out was the original. Head it changed and everything was okay. But beware, in my case the car suddenly would not rev above
4000 in normal drive. Back to a diagnostics centre who tested the alternator which was fine but because of the battery problem it indicated a low voltage and had put the roc into limp mode. Attack clear of the fault codes and reset and car was back to normal.

[lewisheywood]

Thanks Tom , I'll bare that in mind

I did clear all of the codes created from the flat battery so fingers crossed will not being having any issues.

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[blower]

If the battery is OEM and over 3 years old, then one deep discharge and its toast.
You can charge it all you like, it won't hold and will keep loosing charge.

People don't realise that in modern cars with their high current drain, batteries are lucky to last 5 years - usually all it takes is one cold winter and even a battery that's 3 years old can die....permanently.

[lewisheywood]

Thanks Blower, I too was under the impression that they lasted longer nowadays but what you say is understandable.

Just replaced the battery with a Yuasa 096 Silver, with more than double the starting power and a higher AH value than the standard one.

The car turns over a tad faster now which is nice. Hopefully that's the end of my issues, reading 13.9 when idling and 11.8 with engine off. Expecting to see those numbers rise a tad once charged.



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