Battery not charging
 

I have a 1990 Audi 80 which has been sitting around for about two years because it needed a new starter.

Well I finally got around to installing the starter. When I cranked her over it started slowly but ok, figured it was due to the long time sitting. Next time I tried to start it, car would not start. Probably bad battery right, replaced with new battery. Ran fine for 2 days then it died again. Battery appears not to charge. Replaced the alternator, same thing happens. Voltage at battery does not change (go up) when the engine is started.

Now I am kind of stuck. What else could cause the battery not to take a charge considering a new battery and alternator? Could the new starter installation in any way affect the ability of the alternator to charge the battery?

Anyone have a troubleshooting checklist for this kind of problem or any suggestions at all?


Thanks

Check your voltage regulator .........
 

and all wiring to and from it. Test the Alternator to see if it's putting out the correct voltage and if it is then check the voltage regulator next.
Then report back your findings.
good luck

check your grounds, from engine to frame, frame to battery

Your battery sitting for 2 years has sulfated and can no longer hold a charge. If you have a voltmeter check the battery, if it's <12V it's stone dead and most likely will not take a charge. Spiral cells like optima can sit for much longer but flooded batteries cannot. Good change your battery if between 10.5-11.0 is beyond reconditioning.

If your going to let a battery sit for 2 years you must have it on a trickle charger like batteryminder that also pulses the battery to clean it.

I've improved batteries but "cleaning" them.

Look for Ctek chargers on Amazon, great charger. I bought the top of the line and I am very happy with it.
Ctek chargers turn off once the battery is topped off and only top off once it loses a few volts to always keep it full.

If you bought a reman Bosch starter it would come with a new voltage regulator.

I second the grounds, you can remove the main battery cable and sand off any tarnish and reinstall.

New battery [if that battery is good] and alt it should not have this issue.

well, he replaced the battery, so that's not part of the equation anymore. but the charger that you mentioned is a good idea if you are letting the car sit for too long.

If you suspect a current drain disconnect the negative battery cable and connect a multimeter common lead to the negative battery cable and the other lead to the negative battery terminal. Set the multimeter to milliamps and if there is a drain it will read on the multimeter. Start pulling fuses to isolate the circuit. When the drain stops you have the correct system. This is per the Fluke 88-V multimeter manual.

Well, my bad, alternator cable not attached
 

I want to thank everyone for their suggestions I certainly learned from them. In this case it was mechanic error. I began to check voltage drops across battery and alternator and found an open circuit from Battery + to alternator B+ terminal. Turns out the alternator has a separate cable going to the starter then another from the starter to the battery. Since when I took the old starter out I was working blind (starter is buried under the engine you can't even see it until its out) I must of missed the separate cable from the alternator.

After taking everything apart again, and connecting the alternator cable all is well. As the saying goes, there is never enough time to do something right but always enough time to do it twice.

Thanks again to everyone.

LOL

That would do it, the starter is grounded by it's base, the hotwire has to be attached.

Least it's not as bad as you thought, you have a new battery now too. Just make sure to take care of it if you want it to last many years.

Decent batteries are expensive these days with an average 100 bucks for top tier companies and 160 or so for orbital/spiral cell varieties.

Alternator
 

so did you replace your alternator with an after market one or did you get an original Audi alternator?