voltage problem in 84 scirocco

Aug 27, 2003 2 Replies
P

I just had to replace my battery in my 84 scirocco hoping it was just the battery. I checked the old battery with a votmeter and it read



12.55v with the car off. As I tried to start the engine the voltage dropped to about 4.5v and the engine wouldn't turn over. After replacing the battery I got a somewhat higher reading before starting, it dropped to about 10.55v while starting. I am blabering on about nothing. I guess the important part is that with both bateries new and old the alternator only uped the voltage to 13.23v with no electronics on and 12.86v with al the electronics on. I wonder was it really the battery? Or time for a new alternator? Peter
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N

12.8 is very marginal - it will keep the car running but will barely charge the battery if at all. I'd check first your battery cables and the harness going to the alternator - probably some corrosion on the battery cable ends and the harness to the alt. can burn up when it gets old (really! It happened to me!) if all that checks out try new brushes and if that doesn't work might be time to consider an alternator.

Oh... if your alt. light doesn't come on when you turn the key on, the alternator won't get excited properly. That's the "blue wire" that plugs into the alt. - it gets +12V from the battery when the key is on as a reference/exciter for the alternator. If it doesn't see that - no charge. (as an added bonus, since the light isn't hooked up, you won't get any warning until all your lights go dead and the car starts sputtering.)

good luck,

nate

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