Lumpyd

Here I go again on my 98 A4 2.8.

On my way home from work the other night, the battery and brake lights on my dash started to dimly light up. The alternator had been making a high pitched squeaky sound for a while and so I had it replaced this past saturday. The battery is only about a year or so old. When I woke up sunday, the car was dead. Thought I left something on. Jumped it, and drove it throughout the day. Woke up today (Monday) and it was dead again. Jumped it. drove it about 30 or so miles and on my way home, the same 2 lights turned back on. And I was running no accessories or lights. Everything was off. And the indicator on the battery says it's fine.

Any thoughts on what to check next?

Kris Hansen

I'd consider checking the actual battery cables if the new alternator checks out as actually working.

twentysevenlitres

Check voltage at the terminals with the engine running.
Should read between 13.7 and 14.5 Volts.
Check this against battery with engine off - should be between 12 and 12.5 Volts.

That will verify the alternator is working correctly.
If the alternator is brand new, sometimes the brushes need to "bed-in" to the slip ring to make constant contact. I recently installed a new alternator on My girlfriends Ford BA Falcon (Australian model), this took a few weeks to charge consistently at idle (was fine above 1000rpm, but gave the battery light at idle). Operates perfectly now though.

Next check is to grab a multimeter and check for a "parasitic voltage drain".
How you do this is to shut the car down completely. All lights off, all doors shut, ignition off...
If your bonnet (hood) has lights, you need to rig the switch to think the hood is closed, or disconnect the lights so they're off.
Ensure you have any relevant radio codes etc...
Now, disconnect the negative terminal on the battery.
Switch on your multimeter. Set the function switch to Amps in the range of 10-20Amps at the upper scale (lower and you risk damage to multimeter circuitry if there's a power spike). Ensure the multimeter plugs are in the correct sockets for Amps - some need the positive terminal moved between voltage and amperage sockets.
Now connect the multimeter in series with the battery negative terminal and the negative lead (in series means you put the one lead (-ve) of the multimeter on the negative lead of the car, and the other lead (+ve) of the multimeter on the negative post of the battery) and ensure the cars negative lead does not touch the negative terminal of the battery.
**Under no circumstances should you turn on the ignition or attempt to start the car with the multimeter connected in this fashion**

To read the situation, you need to wait a minute or so, as reconnection of the battery (even through the multimeter) may restart certain functions of the car which may need to cycle through before settling back down.
After a minute or so (give it a few to be sure if it doesn't settle quickly) the amperage should read no more than 0.5amps. Even 0.5 is high, but it won't flatten a battery overnight.
For an example, my S8 pulls 0.22amps when everything is shut down - and this has an internal motion sensor running whenever it's locked (plus the usual alarm, radio memory, clock memory, trip memory, flashing LEDs etc). I've had it sitting for over a week and started no problem on the new battery. On the old battery, I didn't even get 3 days! And that was supposedly replaced last October...

If your car pulls 1 or more amps, you have a parasitic drain. Post back here and I'll go through the diagnostic procedure to find it.

If it pulls amps around the 0.2 area (or less), this is perfectly normal.
In which case, despite it being "only 1 year old" the battery is stuffed - sorry!

Lumpyd

Thanks so much Marty. I'll try that over the next day or so. What I have done to this point, is to check how it is charging while the car is running, and it is at about 12.5 with no accessories on. The battery and brake lights are brighter while at idle and dim when over 1000 RPM. But, even on the highway, they don't turn off. I charged the battery for about 4 hours last night and it started fine this morning. Which is a good sign. But the lights continue. I'll try this and get back to you ASAP. Also, what about the voltage regulator? Easy to check? could that even be the problem?

Lumpyd

Nope. No drain. I was at a .23. I don't get it. It's doing the exact same thing as before. New alternator, didn't seem to do a thing. I would think that even if the battery was crap (BTW, when I disconnected it, it was holding 12.5 amps or so) wouldn't a new alternator charge at 14.5 or so? It should turn the lights on the dash off I would think. They get dim, but don't go out completely.

twentysevenlitres

It sounds like its not charging to me, or is having trouble if it is.

If the alternator is brand new, I would be checking connections. Odds of a failure on a new alternator are pretty low (not impossible mind you).

Best place to start is the Earths.
On B5's, the negative terminal goes straight below the battery and bolts to the body on the bottom of the plenum chamber. That is the only earth from the battery, everything else earths to the body.
So check that. I'm not sure if it uses a captive nut - I expect it does, but could be worth checking somehow in case you loosen it and cant tighten it again! But loosening it, spraying some sort of contact spray or WD40 or something and tightening back up will ensure good contact.
Same goes for the alternator. Can't remember exactly how that goes, but I think it does a similar thing, earths to the engine and/or body from the alternator housing. Then there will be another earth strap from the engine to the body.
Make sure all the bolts are tight and not corroded at each end of the earth straps. Any dodgey straps replace them (generics from an auto parts store, or an auto elec can make them up reasonably cheaply).

After that, you need to check continuity of the live wire from the alternator to the battery. On the battery positive terminal, there should be the thick wire for the starter, and a thinner wire attached on the side. I stand to be corrected here, but the thin wire should come from the alternator (it could be the main accessories feed though).
Your multimeter should have a continuity tester - I think it looks like a diode (something like "") and will beep when you touch the two probes together. simply put one end on the positive terminal at the battery (well, preferably the lead, but you'll achieve the same result) and the other at the positive terminal of the alternator (you may need to rig an extension wire). If it beeps you have continuity of the wire.

If the earths are good (you can continuity test these too, alternator earth to battery earth) and the postive wire from the altenator has continuity to the battery positive terminal, then there's no reason it shouldn't charge - thats all the alternator needs to work.

Replacing the voltage regulator is a possibility. They're cheap enough and available at a few places (I bought one at FCP Euro I think). I'm pretty certain removal of the alternator plastic back plate is necessary for fitment though, so you'd have to remove the alternator to do it. I would only go here if everthing else checks out. But the smarter move at that point (as you'd need to remove the alternator anyway) is to have an Auto Elec test the alternator - as a new alternator will have a warranty.

If that checks out, the only option left is to replace the battery - however, it seems to be accepting charge from your mains charger, so it should accept charge from your alternator...
If the cells are all producing voltage, you will get 12.5 volts (or thereabouts) when you chuck a volt meter across it. However, that tells you nothing about the condition of the battery (other than all cells are basically functioning). You need a load tester, which isn't a simple thing, or an electrolyte testing kit (condition of the electrolyte tells you quite a bit about the condition of the battery overall). An Auto Elec can do both, or you can rig up something like a car headlight bulb and see how long it take to flatten - a few hours at least...
By the way, running your battery this way (discharging and recharging) isn't good for it and can lead to premature replacement.

Lights on the dash (should just be the battery light) are set up to be a charge indicator. I'm not sure what triggers them, but probably something like less than 13 volts in the system...

Lumpyd

OK, before I dive into trying all of these suggestions, is it possible that a small amount of oil from a leak could have gotten inside the alternator and is keeping it from doing it's job correctly?

Lumpyd

Went to Auto Zone and had it tested. Voltage regulator. Gotta take the car apart again. UGH.

twentysevenlitres

Oil getting in alternators is very common at causing failures.
My GF's Ford Falcon (Aussie model) recently had the alternator fail. It was the direct result of a leak in the power steering pump, which was mounted directly above it. The leak was fixed, but within two weeks the alternator was totally shagged.

If you know there's an oil leak in the vicinity, either fix it, or (as a mate of mine suggested) rig a shield over the alternator to keep the oil out. Not as silly as it sounds when you see the set up on the Falcon!

wankel7

On my 2000 A4 with just over 200k on the clocks stopped charging. We pulled the alternator out and pulled out the brushes. All worn past the spec...5mm?

Anyways found a good article...

http://www.myturbodiesel.com/wiki/al...oting-vw-audi/

Ordered these brushes...


After a little frustration the old brushes got desoldered and the new brushes in.

On ticks the 200000 mile alternator!