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98 9-3 Flattens Battery for no apparent reason!

Hi Saab Dudes

My 98 9-3 has an unfortunate habit of flattening its battery for no apparent reason. I've replaced the battery and checked that all the ancilliary lighting goes out (glove box, boot etc). The only other thing I could think of is the interior temperature sensor, which has a small fan fitted to it and usually stays running long after the car has been locked.

For now, I've disconnected it, but I wondered if anyone knew how long the thing is supposed to operate for after the car is stopped, why it needs to run on and if anyone has ever had problems with these devices.

Many Thanks

Steve

Reply to
Steve Shuttleworth
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Shut the car off. Wait a few minutes for the interior fan to stop. Disconnect the battery positive cable and put an ammeter in the line between it and the battery. Look for a current draw. There will be a little at all times, but not much. Someone here can tell you how much is normal. Your's will likely be higher. Start pulling fuses until you find out what is drawing current.

Reply to
still me

hi, i`ve had a similair problem. the alternator charges fine but when left overnight it flattens the battery, if the rest of the electrical sysytem is ok , then more than likely a diode in the alternator has failed, they are devices which allow electricery go one way only , if they short , thay can flatten the battery., mark k

"Steve Shuttleworth" wrote in message news:_bSLi.50280$ snipped-for-privacy@newsfe5-win.ntli.net...

Reply to
mark krawczuk

"Steve Shuttleworth" wrote in message news:_bSLi.50280$ snipped-for-privacy@newsfe5-win.ntli.net...

Yes, it is.

I don't know why... but they can clog up with crud, which makes the AAC think that the car is much warmer than it really is, then subsequently freeze you whilst driving along. :)

Reply to
DervMan

Normal is less than 50mA. If you find a current of 200mA or (in your case probably) more, measure the current that flows through every single fuse (while battery connected and car shut down) to find out which circuit is affected.

Looking at the manual you'll then have an idea which components might cause the faulty current.

/T.

Reply to
targa

Sorry, didn't read properly. Pulling fuses will do as well but might be a bit more inconvenient. /T.

Reply to
targa

Actually, I like your approach better than mine.

Reply to
still me

Thanks for all of your help guys. I tried all of your suggestions but to no avail. I have a strong suspicion that the little fan thing for the air conditioning has an intermittent fault and very occasionally doesn't shut down at all. Sometimes it runs for 20 seconds, sometimes for 20 minutes and sometimes for several hours.

As everything seems to work with the fan disconnected, that's the way it's going to stay.

Once again, many thanks.

Steve

Reply to
Steve Shuttleworth

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