[V8] Battery draining possibilities?

[dsaad at icehouse.net]

How are they measuring the current load? You will need a good meter to measure
accurately in the milli and micro amp range. I am not really sure what a
"normal" load would be, but I would guess less than 100 microamps.

1/10 of an amp is 100 milliamps. This is a significant load and will drain a
battery over time. This works out to about .012 watts, or about one standard
incandescent instrument panel light bulb. Not enough to drain a full battery in
a day, but a few weeks maybe. A small leak like this tends to keep the battery
discharged enough that the alternator has to always work hard to pump it back
up, causing both the alternator and battery to work hard and wear out.
I wonder if you are using the correct battery? Your usage seems to be quite
high. These cars take a pretty high capacity battery so if you are using too
small a battery, the normal alternator charging current may be killing them.

The usual method to locate the current leak is to disconnect the door switches
and set the car into its shut down mode - meaning the retained power system is
off, interior lights off, etc. Then measure the current draw and start removing
fuses until you find the leak.

Dave



Quoting Karl Middlebrooks <coalblacksmith at gmail.com>:

> V8 #1, which started eating batteries (went through 3 or 4 in the course of a
> month) in December finally got towed to the shop yesterday with what I
> thought would be problem(s) with the alternator, voltage regulator, or
> charging system.
>
> The folks at the shop got the car up and running after blowing carbon gunk
> out of the valves to get compression on the cylinders again (proof that the
> V8 hates just sitting around with nothing to do for a couple of months),
> recharged the battery and found no problems with the alternator, the voltage
> regulator, or the charging system. Amperage was great, and with the car off,
> it's pulling less than 1/10th of an amp, according to the mechanic. They
> weren't able to find a short or anything else that might explain the original
> problem.
>
> Anyone have any ideas what might be going on here? When the car started
> eating batteries, it would work fine one day and then less than 24 hours
> later, the battery would be dead enough that sometimes the central locking
> system wouldn't even work. A jump start would get it running again, and then
> one day, it wouldn't jump any more. I'm absolutely vigilant about turning off
> lights, stereo, and other doodads that could draw power when I get out of the
> car (e.g. car phone charger).
>
> I'd like to have the car in good working condition. It's been pretty well
> taken care of, and I hoped to get it up to at least 300,000 miles before
> thinking about doing something drastic with it, but if I can't figure out why
> it might have been acting up, I'd have to look at parting it out.
>
>
> _______________________________________________
> Audifans V8 mailing list
> Send posts to: mailto:V8 at audifans.com
> Manage your list connection: http://www.audifans.com/mailman/listinfo/v8
> Have an Audi V8 question?  Check the Audifans Knowledgebase!
> http://www.audifans.com/twiki/bin/view/Audi/V8
> Have a V8 answer? ... Please help others by adding to the KB ... all
> contributions welcome!
>