Battery draws down when my car stands for a few days

Get out your multimeter.

Remove the Ground strap from the battery.

Set meter for Milliamp range (a high range). Connect the meter Red lead to the ground strap. Connect the meter Blk lead to the battery Neg post.

Make sure the Interior light and any other accessories are off.

If you read on the order of 50 milliamp or less, there is no significant drain.

If you read something like 500 milliamp or more, then there is a real problem. In that event, try removing fuses to narrow it down. Finally, take the big Red/Wh lead off the Alternator B+ terminal.

Post back findings.

Speedy Jim

Crazy question. Can i pmail you a picture of my multimeter? It has more functions than i know what to do with, and I know how to use the ohms setting and Volts........not sure about the amps. I will check this out today.

BTW, I dorove the vehicle yesterday, and the volts gauge never got above 12.5 during the day with no accessories on.......fan belt is not slipping........

If you e-mail a JPG attachment, check the file size to see that it is under 100K Byte.

Speedy Jim

Sorry for delay. I found a website that explains multimeter, and will get into that tomororrow. But I went to the VW shop yesterday, and tested the battery, with load and with out, and the charging.

without load 12v. With load it drew down under that. When the car was running, it was maximum of 13v, with no accessories on. When i added lights, etc, 12.8v. So, looks like starting place is the alternator, would you not agree? Get the charging system up to par. I have replaced the brushes in a different alternator years ago...In your experience, if doing this in the 1-wire alternator, would it solve the problem?

Then I will get to finding short tomorrow.

I doubt brushes are the problem. First, try another meter to be sure of the voltage readings. Put the meter right on the big B+ terminal on the alternator to measure.

If voltage at B+ is still low, possible that the internal regulator is bad/out of calibration. This would be really rare.

Jim

I will check today.....and post findings. I definately want to be sure with the price of a new alternator what it is.

Make sure the grounding strap is clean and correctly installed on the transmission. Also make sure that the alternator is grounded well also. That might improve the charging voltage.

Also check for drains on your system with the engine off. Do you have an alarm on this vehicle? Possibly a relay causing the drain while vehicle sits for a few days. Possibly alternator is causing all of your problems, so I would probably check for electrical drains with it connected and disconnected.

JMHO

In my opinion, a battery that shows an even 12 volts with only a meter hooked up to it, and draws down below 12 with a load, is a bad battery. The alternator may be trying to put a lot of work into a battery that has sulfided, or has a shorted cell. If you can, I'd try a different battery. Or, to try and rulle out if you have something draining it, charge it up with a battery charger, and measure the voltage every day or so and see what it does. Do not hook it up to the car. The first day it might show high just from the charge. You're looking to see how much it decreases over time. A healthy battery should show about 12.6v at rest.

I am going to pull the battery today and have it tested. It is an Optima, so they should replace if bad........

My battery checked out fine........so my quest for a reasonable price on a Bosch AL82 alternator begins.........

If your battery "draws down" when you let it stand for a few days, tell it to have a seat and stay awhile.

Rich

FINALLY got a chance to do more testing. I fully charged battery, and reinstalled. Started car....voltage at B+ is 11.97 V..........thus I believe alternator has a short in it or something.

I have ordered one, and when I reinstall I will test again........and look into whether there is a short in a circuit as well.

why not install new brushes or regulator?