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I have a 2002 Golf. I put the car on the drive on Friday night and tried to use it on Wednesday and it was dead. No lights, no display nothing. I came home and jump started and it ran fine. No stalls etc etc. About 2 weeks ago the radio stopped working but as far as I can gather all the additional electrical systems are fine...heated seats etc. After the jump the radio was working. Does this point to the alternator not charging the battery and thus a dead battery or a bad battery that needs replacing. Incidently it was below 0F last night.

Thanks,

Follow up to comments.

I don't have enough points to comment back sorry.

  • The radio is factory installed.

  • Can i use the voltmeter on the battery charger if its not connected to the mains to see the change in voltage ?

2/4/2016 I don't have enough points to comment back sorry.

  • got a voltmeter. 12.4v when powered off. 14.4 v running.
  • took car to oreily they tested the battery and alternator said it was behaving perfectly.

So was the issue caused by the 3 days of not driving and the cold ? Is the radio being off a red herring and has nothing todo with my current issues just an unfortunate coincidence ? Its been working for the first time in 2 weeks today since being charged last night.

  • Is the radio stock or aftermarket? – Dee Feb 4 '16 at 2:29
  • You could try with the voltmeter on your charger, it probably won't be all that accurate however. I have also added to my answer. There is no problem updating your question to add more information. – HandyHowie Feb 4 '16 at 8:44
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If you have a volt meter that you can connect to the battery you will be able to check the alternator.

Before starting the engine, check the battery voltage, it will probably be a little over 12v. Now start the engine and turn on your headlights to draw some power. If the alternator is working, the battery voltage should now be between 13.8 and 14.4 volts.

It would be a good idea to clean the battery terminals and the connectors to ensure there is a good contact before replacing the battery if everything else seems fine. Make sure you have your radio security code before disconnecting the battery if you have one.

You could also check that there isn't much current being drawn from the battery while everything is switched off which could have caused a flat battery. You will need an ammeter for that, which you will need to connect in series with the battery. It is possible that your radio had somehow gotten into a state where it appeared off, but was drawing power all the time.

If you haven't got a voltmeter, you can get an indication of whether the alternator is working by watching to see if your head-lights dim a little when you stop the engine running.

If after jump starting your engine and driving you were later able to start the engine without jump leads, this pretty much proves your alternator is working, because it must have put the power to restart into the battery. It doesn't prove that it is providing the correct voltage however.

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