[928uk] Another Battery Question

[Nick Carrington]

Ah yes, in theory. However, as we all know:

In theory, theory and practice are the same thing, but in practice they are completely different.

My battery drains in about 2-3 weeks. My interior lights are all set to permanently off. I have an alarm but rarely activate it (certainly never in the garage). My seats have no memory. I have no fuel computer. My rear window demist does stick on, but that drains the battery in hours, not weeks (as I've found out to my cost before). One day I'll go through all the pain of a current leak detection exercise (you can't expect to test individual circuits separately and easily find the cause because everything in the car shares a common earth), but for now I flip the battery isolator switch and reset the clock when I go out in the car next time.

Best of luck Owen.

Nick C

-----Original Message-----
From: 928uk-bounces at 928.org.uk [mailto:928uk-bounces at 928.org.uk]On
Behalf Of ukkid35 at breathe.com
Sent: 01 April 2004 15:17
To: 928UK
Subject: [928uk] Another Battery Question



I am always puzzled by these battery drain queries. The battery in a 928 is 
larger than just about anything you find in a petrol engined car, from 
memory 72 Amp Hour. This means it should take a month for a current of 50mA 
to half drain the battery, which should still leave enough to start a 
healthy car on a winter morning. I'm guessing that a properly installed 
alarm/immobiliser should drain less than half that. However to be sure I 
will check and report back what the current drain is on my car which has two 
immobiliser/alarm systems fitted (one by Porsche? and a Laserline system by 
a PO), both which need to be deactivated to start the car. 

I honestly believe prevention is better than cure (lesson learnt from my cam 
belt experience) so if your battery can only last a few days before failing 
to start the car, you need to know what is draining it. As Kingsley said 
http://www.nichols.nu/tip800.htm is a good place to start. 

Possible canditates also include sticky Rear Window Defrost relay, as well 
as bizarrely the memory seat function (perhaps this is because the servo 
can't find the right position and keeps trying to correct). Also check that 
none of the interior lights are set to permanently on. 

I really can't see why a battery conditioner should be neccessary unless 
either you live in Alaska or only drive your car very short distances at 
night once a month. 

Paul 

87 S4 Manual
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