View Full Version : Possibly a Bad Alternator...!

01-29-2017, 08:20 PM
I have been having an annoying issue with Battery/Alternator since i bought the car 4 years ago.

When i bought the car the battery wouldn't hold the charge if the car sits for couple days even if it was fully charged, and the needle on instrument cluster would stay around 12v whilst the car is running especially with the headlights on/ or A/C. So i replaced the battery and no longer an issue with charge but sometimes the needle sits just around 12v and if activate the window switch (see below video) it would jump around

Also when the car sits for 8 or more hours, i put the ignition on and the battery needle is around 9v and never starts immediately without couple cranks on the first twist of the key.

So my question is, does this sound like a bad Alternator...


2001 Audi A4 B5 V6 2.8l 30v


Sent from my iPhone using Audizine (http://r.tapatalk.com/byo?rid=87676)

01-29-2017, 08:52 PM
Charging should be around 14v when the car is running and battery should be at around 12.4v resting, looking at your guage it's fluctuating which it should not be doing, mine just stays at 14 and moves only tiny bit when switch on loads. It looks like a bad voltage regulator to me

01-29-2017, 08:56 PM
You either have a bad alternator, or a bad voltage regulator (built into the alternator) from what you have described. While the car is running, the car shoupd be very close to, if not exactly on 14 volts. 9 volts is barely enough for your starter to cooperate with you. So I would take the alternator somewhere to have it tested, even like Autozone can do it. Or you can do it yourself if you have a load tester. Basically the hook up the battery to this tool, and it seeks any problems in the charging system. If you alternator or regulator is the problem, I would just replace the whole alternator. You could find one cheap from a part out if you don't want to buy new.

Edit: definitely one of the two I mentioned. You can expect a little fluctuation when adding load, such as using the headlights, but your needle should never move that much. The issue really isn't that your battery isn't charging. It is that it isn't receiving enough charge. Should always be around 12-12.5 volts after running the car.

01-29-2017, 10:49 PM
What brand should i go with and would a Remanufactured OEM be ok..

01-30-2017, 03:56 AM
Remanufactured should be okay as long as it is tested and has a warranty. Valeo is OEM. Not too sure who else builds these. http://www.audizine.com/forum/showthread.php/358309-DIY-5-Alternator-Fix-replacing-brushes-(Valeo)

I'd check this post out before replacing the alternator though.

01-30-2017, 04:15 AM
Most alternators you get from advanced auto, napa, places like that have lifetime warranty. And my guess is it's a bad alternator. My car sits around 14.2V when running, only dips a little, maybe halve a bolt when adding load, then it goes right back up.

01-30-2017, 05:59 AM
Don't buy autozone, first time I got shipped the wrong one. Second time I got the right one but it's barely better than my old bad one, still have problems with it and it makes a weird droning noise too.