+ 1 probably, exasperbated by a weak battery.

 

Please note that many trickle chargers usually needs minimum 8 volts to even start charging. Most trickle chargers cannot wake a dead battery to life. Then you need a normal more powerful charger.

 

There is a simple, inexpensive test for parasitic draw. (The battery must be fully charged) First loosen the one of the battery cables but do not remove it, then clip the alligator clip to the clamp part of the battery cable. Take the pointed end of the test light and apply it with a little force to the battery post, when you are ready carefully lift the battery cable up from the battery post making sure not to loose contact at with the test light connections. The test light should not light up, if it does you have a parasitic draw, or did the test wrong by momentary loosing connection of the test light. If it passes this test and the charging voltage when running is over 13.2V, I would replace the battery. These 2 test should take you less than 5 minutes, and at the very cheapest $18 for a test light and throw away volt meter.

 

Cross Thread is right at 13.2. I mis - typed 13.6 earlier. Disregard that please. Figure 2.2 volts per cell on a lead acid battery.

With all the computers and security features on modern cars (and especially the 911 which seems to be a battery killer) will you not see some parasitic currents anyway? These would need to be pretty high to drain the battery as you filled up with gas. And if that was the case, the trickle charger probably would not have created enough charge to start the car in the first place.

Remote diagnosis can be very tough to do. Fortunately a battery & starter is fairly simple to track down. Remember, the 997.1 was notorious for slow cranking due to poor cable crimps. Back to connections ... It's too bad the cable is such a bear to change.

 

Apologies ... just realized the original post was battery drain (September) while I have been referencing my comments to the recent post on the Targa. Two different problems with two different approaches.

 

Re parasitic draw... not zero. 997s draw (by design) about 45mA when shutoff. More that that would be an extra load.

And... a functioning charging system develops more than 13.2V across the battery terminals - 13.8 to 14.2V is typical.

 

100% correct on the functional, but ever charge a failing battery? No excessive draw, charging at 13.2 volts, and battery goes dead in a few days. Hmmmm

Did not want someone chasing their tail when it is as simple as replacing the battery. During my 17 year career of turning wrenches I saw it happen on numerous occasions.

 

Update: replaced the OEM battery. When starting the car turns over crisply and does so after driving for long periods of time.

Looks like the battery had reached its end of life (after several years of use).

Thanks to everyone for your feedback and troubleshooting tips.

Cheers!

 

I'll add this just in case someone uses the search history for this thread.

I recently did some troubleshooting on a parasitic drain. the source was a recently installed ODB Bluetooth device. It was not shutting down. Whether that is by design or not, I do not know.

This was not a Porsche, but maybe it will help someone else.