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Parasitic drain possibly found

A

Avon

Trainee
Joined
12 Mar 2016
Messages
79
Fellow battery drain sufferers...

Battery would struggle to last a week. Today discovered the engine compartment light (had no idea it even existed!) And it wasn't lit when engine cover open.

Bulb appeared fine, tested ok with multimeter and connectors were giving 12v... then noticed that the bulb wasn't seating correctly in the holder and the design is such that it is easy to short circuit the terminals if the bulb isn't in correctly. Reseated it properly and now it works.

Hopefully this works! However I do wonder if it would matter because the circuit would close when engine cover is down? Any ideas folks?
 
Im a little dubious to be honest .. great if it is that though .

I had a quick look at an early 996 wiring diagram and the boot switch gives the earth to the light as well as the control unit ( alarm ) , the feed again comes from the alarm control unit , boot closed and no earth .

I would have thought that if a short to earth happened on the feed to the light then the alarm cu would stop the feed .

It may be a different wiring setup on your car but thats how it works on the early ones .

To find a drain you need to either pull fuses with an amp meter connected or use an amp hound .. dont pull any alarm fuses though .

996 and the majority ive found have been on the audio system or the glove box light staying on .
 
Mine ran 24x7 and drained the battery, due to a fault in the switch element. Bulb now removed :)
 
Demort said:
Im a little dubious to be honest .. great if it is that though .

I had a quick look at an early 996 wiring diagram and the boot switch gives the earth to the light as well as the control unit ( alarm ) , the feed again comes from the alarm control unit , boot closed and no earth .

I would have thought that if a short to earth happened on the feed to the light then the alarm cu would stop the feed .

It may be a different wiring setup on your car but thats how it works on the early ones .

To find a drain you need to either pull fuses with an amp meter connected or use an amp hound .. dont pull any alarm fuses though .

996 and the majority ive found have been on the audio system or the glove box light staying on .
Click to expand...

Thanks for the insights but I think you're right - unfortunately - as it doesn't seem to have changed the drain rate. Oh well time to get the multimeter hooked up and start taking yanking fuses...
 
A battery drain happened to my 2001 996 a couple of years ago. Turns out the ignition switch was on all the time. As i live in London and don't drive for maybe five ti ten days at a time, I kept going back to a dead car. Three visits to the garage before it was diagnosed.
 
Battery Drain

Hi Guys, whats a typical drain reading with alarm off?
 
On a 996 then it does a lambda burn off for around 30 mins so it will read around 1 amp or so for this time .. it will then drop to around 40 milliamps depending on just how long you leave it and keep checking it.

Rule of thumb i work by is as soon as i see less than 0.1 of an amp then im pretty sure theres no discharge when looking for a flat battery fault .

The car will go to sleep wether alarm is on or off and the readings will be the same .. it just takes longer .
 
Yeah thanks DeMort that's what I got 40milliamp. Just trying to find reasons why my Bosch silver battery died, but don't know how old it is, but it wouldn't hold a charge anyway so replaced it with a uasa silver from halfords,good price with trade card £92😁
 
You can get intermitant drains .. a tracker battery for example gives a pulse discharge every 40 - 60 seconds of 1 amp for a few seconds when its faulty .

You might have a weak alternator .. check the output with the lights on main beam , blower on etc etc and read off the value .. it should be above 13 volts if all good.

Batterys when they do go totally flat Really dont like it .. the Porsche ones often used to die at that point but basically a totally flat battery is not good for it reguardless of the make .

BTW .

Your the first person that has ever said my name correctly even though its not on my avatar that way .............. De Mort :D :thumb:
 
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