[s-cars] Battery update, C4 A6

[Fred Munro]

Kent;

Good process list. I went through this with my S4. You'll want to have the
doors closed when you are checking the amp draw - I used a meter with a
large display and set it beside the battery where I could see it through the
rear door window.

A normal draw on my S4 was 100 mA for the first 30 seconds after the alarm
is set, dropping to 10 mA with a spike to 20 mA every 5 seconds.

The culprit in my case was a failed auto-close relay in the power window
circuit.

Remember to pull the circuit breakers in the relay box under the hood as
part of your check process. Not everything is protected by the fuses in the
fuse panel.

Good luck!

Fred Munro
'97 S6




-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Kent McLean
Sent: December 30, 2008 9:58 PM
To: s-car-list at audifans.com
Subject: Re: [s-cars] Battery update, C4 A6


(this bounced, so I'm trying again)

Lee Levitt wrote:
> Now, if I can figure out why my RNS-E is killing the battery in my
> C5 A6, I'd be a happy camper!

My 20V200 TQA has a slow battery drain (kills the battery over 2-3 weeks).
I need to go through the debugging routine. If anyone wants to correct me
on this, please do.

Finding a battery drain:

1. Disconnect the + cable at the battery.

2. Connect a DVM between the + terminal and the + cable.

3. Set the DVM to measure milliamps (and don't try starting the car).

4. Note the amperage you are starting with. (If it is less than X ??? ma,
there
is no drain. The radio (memory) and alarm system? will produce a minor drain
on
the battery. We are looking for a bigger drain that kills the battery in a
week
or two.

5. Pull one fuse at a time. Note the change in amperage.

6. When you pull the fuse that makes the amperage approach 0, you've found
the
drain.

7. Replace that fuse and keep going; you may have a 2nd drain on the
battery.

8. Determine which loads are protected by the fuse identified in step 6 (or
7).

9. One at a time, remove each load to see which one is causing the drain.

10. Repair or replace the problem found in step 9.

Comments and corrections welcomed, especially the minimum value that is an
acceptible drain.

-- --
Kent McLean
'99 A4 Avant
'91 200 20V Avant #3
'94 100 Avant, sold
'91 200 20V Avant #2, up in smoke #2
'91 200 20V Avant #1, recycled
'89 200 10V sedan, up in smoke