Blackspeedster

I have a 1999 996 cabriolet with a serious parasitic battery drain. Already been to the shop and was told the drain spikes to 82 miliamps draw then goes flat and spikes again, etc. The key remote had died two years ago and the battery is new. They thought it was the ignition switch an spent $500 replacing that to no avail. I took the car back home and pulled every fuse and still it's draining overnight. No lights are on and the front boot light is disconnected. Any advice? Please help as nobody can figure it out! Think it's the alarm system? Convertible top? Do I need a new remote key?

Thanks in advance!

TamiyaGuy

Are you sure it's 82 milliamps? That doesn't like it's enough to drain a healthy battery overnight. At that rate, it should take days. If it was 800 milliamps that would do it.

If it's only 82, is the battery still good? I understand it's new, but you never know as to whether it's holding a charge.

Bijan

TamiyaGuy is right, you need a few Amps to drain the battery overnight.
Can't see the remote key being the cause.
Assume the battery is good? Was this replaced?

Blackspeedster

It maybe lasts 48 hours is there's a full trickle charge. This is the second battery in the last 90 days. Definitely a drain somewhere in the system. No aftermarket parts on the car at all.

Bijan

Blackspeedster,
It is baffling
Since you have pulled all the fuses with no change, this SHOULD have covered the alarm also.
Perhaps worth doing same with some of the relays, in case one is stuck closed? Best I can think of.
(Assume the system is charging OK, voltage well above 13 when engine is running)

smackboy1

There are a bunch of posts about battery drains floating around. Do you by any chance leave the key in the ignition overnight? Do you close the driver side door and then reach inside the window and pull the key out? That can cause a battery drain.

Blackspeedster

AAHH! This is frustrating! Tried another battery - the 3rd. It's NOT the battery so it's still a drain problem. When I put up the power top, the driver's window no longer does anything but the passenger window moves. Maybe I'll pull the Window relay and see if that does it. Maybe the window relay is stuck open?

Blackspeedster

Anyone know which one is the power window relay?

Blackspeedster

I pulled all of the relays and apparently none of them are for the windows. There must be a window relay somewhere? It's not in the fuse box!

I got my remote finally working as the red LED is coming on but it's not locking or unlocking the car. The car doesn't see the remote at all?

Bijan

Blackspeedster,
IMO time to see an auto electrician, preferrably one that has Porsche or perhaps VW/Audi experience?
It is obviously a non obvious issue
Interested to hear outcome

Blackspeedster

Turned out to be the alternator creating a 3amp magnetic draw on the battery!! Dealer nor an independent could find it, it took a specialist auto electrician.

theonlyrobertson

I had that same issue. Couldn't be alternator I thought, it's a rebuilt only 4 months old, but I traced it to the alt. Disconnected it and the drain when to near 0 a. Put this in the portion of your brain labeled, "things it couldn't possibly be".

Bijan

Sign of the times, alternators are meant to give not take

JDSStudios

I never heard the term " magnetic draw".
What was done to fix it?

Bijan

Here's my 2 cents worth:
One possibility is that the Voltage Regulator was "leaky".
The regulator supplies the current to the field winding (rotor) at start up from the battery. Once the output voltage is achieved it switches from the battery to the output of the alternator. By varying the field winding it adjusts the magnetic field to give the required output voltage. Boring I know...
There is also a rectifier in there that converts the output AC to DC then back to the battery.
Hence the precautions in the manual about the procedure of connection and disconnection of the battery, so the regulator electronics doesn't get zapped.