Squidbert

Ok, I should probably start this off from the beginning.

1. Back in March or so I had a high power stereo system installed into my car (2x12", 600W amp, deck, MB Quart seperates, power capaciter, somewhat mid level, sound quality setup). About a week after, I had a remote start alarm installed (CompuStar).

2. A couple months later, my alternator started to give out. I went to a local rebuilder. They couldn't do anything with the Bosch part, but fitted an AC Delco unit (I know, believe me I cringed. I was hoping for at worst a nippon-denso) putting out 175 amps.

A week after that, I moved to Seattle, but promptly was shipped out of town for a few weeks for work.

I get back, battery is completely dead. Figuring I may have left the dome light on, or a recently replaced trunk pin may have failed, for whatever reason, battery drained somehow. Purchased and installed new battery.

Everything seems fine until a few months later I'm out of town for a couple weeks. I get back and the battery is once again dead.

So, I have all these electric variables, and I suspect one of them may be the source of the problem. What would be a good way to narrow this down? I have a multi-meter and a test light, a battery charger and jumper cables at my disposal.

I think I'll remove the fuse for the stereo system and let the car sit for a few days to see if that may be causing it (the cap has a digital readout, which doesn't shut off after the car turns off. I dunno what prompts it to power off, but perhaps this is causing it?

Another thing that I noticed, even though the volt guage in the dash shows a solid 14-16 volts (it varies, loose belt maybe?), randomly my brake and battery lights will subtly fade in and out together. It also once did this and triggered the abs light as well. Even though it was doing this, the volt meter still read a consistent reading (well above 12v). Perhaps a loose connection with the alternator replacement?

Another factor is that high voltage alternators are "self exciting". At idle speed, they tend not to charge, but charge massively when above engine idle speed.

So I'm at a loss as to how to narrow down this problem. As stated, I do have a multimeter. Perhaps I could measure voltage drop at the battery while isolating seperate ciruits, somehow? Any ideas? May I be on the right track (well, with my somewhat uneducated theories on electronics, that is)? I really want to solve this problem, it's driving me nuts

Thanks in advance, and I'm always greatful for the helpful advice I recieve from all of you guys

Edit: Oh, as a side note, is it OK to charge my battery through the charging post in the engine compartment, and a motor ground? It seems to be working so far. I just don't feel like digging the battery out from under the rear seat

V8QinNJ

Easy.. put a 12V blub inline on the positive battery cable, between the battery and the battery cable.

And then start pulling fuses, when the light goes out, then that circuit is the culprit. And then you can start looking whats connected to that fuse that is staying on.

If I had to guess, they're keeping a relay energized that shouldn't be for the remote start. But what do I know..

You should also let us know what car we're working on ;-)

-Scott

Mister Bally

After trying the usual current draw tests with no results (some mornings no problem, some mornings battery completely dead) ; I waited a few hours after parking the car and then touched the alternator. It was toasty warm. Leaky diode drawing current and heating up the alternator case, which is a heatsink. Replaced alternator and problem solved. At first I thought it was the voltage regulator/brush pack and replaced that. But I still had the problem a few days later and did the touch test and found it warm. We know that the energy to create the heat had to come from somewhere (the battery) and I could not buy the diode carrier and diodes as a service part even though they are shown that way in the service manual so I bought a Bosch reman alternator and replaced it.

SF200TQ

All the above advice is great - put that light inline (or an multimeter/ammeter) and start pullin' fuses...

But when you start testin', pull any radio-related fuses first...

Had the same problem - non-stock radio installed by PO, and (I think) there's something atypical about the way stock Audi radios work, or at least atypical to the majority of radio-installin'-places. It seems (at least in my case) that the line the shop used as the "car is on, turn on the radio" signal line was always hot, rather than keyed on the ignition... so the radio was always on... but just enough to draw down overnight. Pullin' the face plate turned "off" the radio, but it was still drawin', unbeknownst to me.

Pulled the radio, found a keyed-on line, spliced in new signal wire, problem solved.

Might be somethin' else tho, of course - the archives will find many suggestions...

Good luck!

Squidbert

I'll consult the installer of my alarm. He seems like a pretty straight forward guy, hopefully I'll get a good answer from him.

Squidbert

Yeah I noticed on this car (89 200TQ) as well as my 84 4000Q, the stock radios are powered on constantly, unless turned off at the radio. Both cars have aftermarket stereos now, and are wired from an ignition switched lead (I don't care to have to turn my radio off when I turn the car off). Your problems sounds odd though. Even if you turned the radio off, or pulled the faceplate, one would think it should only be drawing enough to keep the radio station memory and clock going. That's odd.

Squidbert

The brake and charging light will come on together. Sometimes they fade in then out, sometimes it's instant, but something's not right. Again, I wasn't excited about a GM part being put into my car. I think my poor kraut ride is rejecting the transplant I'm gonna have them look at it again. I hate dealing with them though. They told me they could rebuild and install the alternator in a tight time frame. When they did, the belt wasn't tensioned correctly and it fell off. They then acted like it was my fault, although they never told me they'd be rushing the job. I would have prefered them to take their time than to rush it and screw it up. Ugh.

itsav8

I agree with Bally...I did the same to my wife's V8..replaced the Alt, problem solved.

1990V85speed

Ron, didn't you do that to my V8 as well?

itsav8

......rite?...LOL.