Battery Drain

Hey Guys and Gals . Just signed up . Got a 06 CaymanS . Bought it about 2 and a half years ago after the previous owner had the car stolen during which it was abused and vandalized . The worste of it was the motor had been blown no doubt due to over reving it . Slashed tires , broken mirrors and windshield , and the body looked like it was pummeled with large rocks . lol Surprisingly the interior ws intackted and in good shape . Im been a mechanic almost 35 years and I decided to take this project on , at which point I became the new owner . Built the motor with al the upgrades starting from a new crank , IMS bearing , studded the heads , etc. Its been running awesome now for 15,000 miles , but since the begining its had a parasitic battery drain issue that I could not determine . I replaced the alternater , checked for excessive current draws , circuit y circuit and finally gave in to installing a power disconnect switch wich I used when ever the car was parked for more than 6 hours. and been living with it that way ever since . It is strange that sometimes it would be fine for 2 or 3 days and at other times it would drain the battery in as short a time as 6 hours . Well I think Im ready to want to eliminate this problem once and for all , if I can with the help of the cayman community . Im not really satisfied having it on a battery minder every night , if possible . So has anyone had this issue before , and what ended up being the culprit , ??? Ive come accross article of others with this problem but nothing i read had a solution to it . If anyone could be of help , that would certainly be awesome . Thanks.

First, you’ve posted this in the wrong forum(you have a 987.2 I think), but maybe the mods can move it. Second, I have not had this problem, but if I did I would put an ammeter on the battery and find out exactly what the draw is. And then I would start pulling fuses until it stopped. That would at least narrow down where the problem lies. Good luck!

Its a long shot, but you aren't leaving the key in the ignition by any chance are you? Lots of guys who keep their car stored safely inside a garage have found this out the hard way, as doing so causes all sorts of things to draw on the battery and will drain it in short order.

If you have a Volt Meter with Milli-volt resolution you could try measuring across each fuse -while the fuse is plugged in- at the two test points on each fuse. You should measure 0.000 volts across every fuse if the car is in the Sleep Mode. Any circuit that is drawing current will show a small Milli-volt drop across that particular fuse especially if it is the kind of current you are describing. A guy on this forum did an experiment several years ago on 987's and if I remember correctly the sleep mode current is about 0.025 amps.

Hi , yes thanks for the suggestion . Actually I have already performed that procedure twice , and both times there was no substantial current draw on any of the fused circuits , which is why I was at a loss at that point . But thank you .

I had a problem similar to this on my '09 Boxster S , although not as severe. The battery would be dead if I left the car more than 5 days. I accidentally discovered the problem at a DE event. I was hanging out with some friends and the car was completely at ambient temperature when the fan that removes hot air from the engine compartment came on. That shouldn't have happened. I replaced the sensor in the engine compartment that turns that fan on and have not had problems since. Of course, there are many other possible causes as well.

Yeah, per screen captures from some unknown source, after 60 minutes a locked car should draw 20mA max. I've pasted the images here - not sure where they came from, but I saved 'em for future reference. I had a mysterious current draw issue in one car that turned out to have something to do with a door switch somehow leaking enough current to drain the battery but not light the dome light enough to see it. I also had a car where the glove box light switch got bumped and did not turn off. Both those issues were in cars in the olden days when things were simple.

https://www.planet-9.com/faq.php?faq=techdata#faq_batterysp https://www.planet-9.com/faq.php?faq=qanda#faq_batteryqa

thanks for rescuing that poor Porsche .... try checking for corrosion on the grounding cable or around the grounding point near the battery .

Maybe it’s superstition...but I always lock my 987.1 with the remote before leaving it sit, and I’ve never had to use a battery tender . I’ve had the car for over 8 years and only drive it on weekends or in nice weather. It frequently sits for weeks without use. My theory is that locking the car that way may help the electronics stay in a sleep state. I also have always run a full-size Interstate battery — and I’ve never let the battery age for more than five years without replacing it.