battery or altenator fault ???

Smirky

Registered User
Ok so my car decided it didn't wanna start luckily 1min from work so got it going off a battery booster, battery was Def dead is there a way of telling if it's the alternator ? Dunno if it makes a diff but had esp fault come up and a little steering wheel light up on the dash both have now gone
 

fouryoghurts

Registered User
Can you get a volt meter on the battery after starting via a good battery? If you see battery voltage only, you alternator is gubbed. You want to see 13-14volts from a good alternator.

If jumping, remove key when making connections and use engine for earth.

ESP light likely due to under voltage. Should disappear upon driving with good voltage.
 
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Smirky

Registered User
I haven't got a volt meter would u not get a warning light on the dash if alternator is screwed ???
 

Sayam

Well-Known Member
VCDS Map User
The warning light you would get is battery discharge which is the same one you'd get for a flat battery if it was knackered.

Best way is to grab a multimeter as has been said. With engine started should see a healthy up to 14 volts. Alternatively (no pun intended) you could charge the battery fully and see if it goes flat again, indicating the alt.
 

Smirky

Registered User
Well I drove home turned off the engine ,tried restarting it straight away and it went just been out again now plugged bluefin in to see if I could do a scan and I can't :( but while was out there warning came on the dash saying battery level low will recharge when driving which is leading me to think the battery isn't holding any charge ?
 

Sayam

Well-Known Member
VCDS Map User
You can't assume mate from what you're describing and there could be tens of fault codes logged when all the different sensors have their brain farts due to low voltage so that won't help.

I'm sure you can ring around and get your hands on a multimeter? Or buy one (they're quite cheap) and then keep it?

With engine started anything 13 volts or higher means its battery and if its less than 13 I'd suspect alternator first. Where are you based? You can swap batteries with me if you're local...
 

Smirky

Registered User
I'm in Southampton but thanks for the offer I'll pop out tomorrow and pick up a multimeter ,what do you put it on the battery terminals?
 

fouryoghurts

Registered User
I'm in Southampton but thanks for the offer I'll pop out tomorrow and pick up a multimeter ,what do you put it on the battery terminals?

Yes. Positive to positive, negative to negative.
Positive = red;
Negative (ground) = black.
 

Smirky

Registered User
Getting over 14 volts when the car is running so assume the alt is fine ,also someone at work pointed out that the battery has a bit on it that's green when the battery is ok and red when it's not and mine was red ,
Cheers guys
 

NHN

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VCDS Map User
TBH I would try charging battery with a ctek 1st, then see if it drops by itself quickly.
 

Sayam

Well-Known Member
VCDS Map User
I'm in Southampton but thanks for the offer I'll pop out tomorrow and pick up a multimeter ,what do you put it on the battery terminals?

Sorry for being late with follow up. I'm in West Yorkshire so that would have been a mission lol

Reading further down you need a new battery so just swap it and see how you get on
 
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