Manual, page 255:


Load switch-off after 2 hours
If key is removed loads ....in standby mode...are automatically switched off to save battery

My take is that (since they later talk about what happens if you don't unlock the car within 7 days) they mean to indicate that "loads on standby" which otherwise would stay on and cause drain are shut off 2 hours after car is locked.

A little something lost in translation maybe.

 

If you leave the hood open or the engine compartment cover open the lights on the hoods stay on...but load management kicks in after about two hours and will shut the lights off. If you leave the hoods open and arm the the alarm you'll get the fault beep on arming but the lights will go off after about 20 minutes.

 

Even with car closed up there is circuitry that remains "on standby" as per manual. They specifically mention lighting systems and radio. These apparently go to sleep 2 hrs after car is locked up.


These are complex machines. Is there any one here who has not sat in their shut down car and wondered about the clicking and whirring that goes on?


In an unrelated post Mac has taken the position that there are no "ghosts in the machine" I'm not so sure.

 

If you check the manual, it states that is does not matter. The only thing involving the key that affects battery drain is if you leave it in the ignition.

 

Somewhat related, if you want to leave either hood open but fool the car into thinking it's closed, flip the hood latch to the closed position. A screwdriver held sideways works well here. Be sure to place a rag or painters tape over the latch it to remind you not to close the "locked" hood. This is a convenient way to keep the hood in the open position for whatever reason you need without battery drain issues.

When you are ready to close the hood, first unlatch it either from the key fob or interior switch to "open" the latch, then close the hood normally.

 

Too much work - easier to just arm the alarm and the lights go out in 20 minutes - not enough time to drain a battery.

 

OK, so OP asked whether locking door increases battery drain. Turns out I and others who had believed it does are wrong. I did read pg 155 in manual but to me it was not clear as to the question. Fahrer read it differently than I and said it doesn't matter. Well...


I refer you to pg 26 in the manual where it unequivocally states that if you DO NOT lock the door w key or remote you DO NOT arm the alarm or internal security systems whose role it is to Monitor doors, f/r lids, glove and passenger compartment and cab top lock.


With that information on hand I think it is safe to say that locking doors DOES INCREASE drain on battery rather than decrease it


I still think however that the best of all worlds is: doors locked with battery tender on. If nothing else battery life is extended quote a bit. That's in the manual also.

 

All this speculation is moot if the car is driven regularly. Based on the posts in this thread, there is no definitive answer, especially not one explained in the manual.

 

Driving car regularly may negate some of benefits of tender but if you do not lock the car you do not arm the internal security system and it is the security monitoring that increases the battery drain which was the original point of this whole thread. It's not so much a question of speculation as an exercise in logic. And we all know how logical owning a Porsche is

 

Your speculation is logical, but I don't not think it is true.

When I first picked up my car the Porsche dealer told me explicitly to keep it locked in the garage as the battery drain is lower. He said leaving unlocked keeps the car in a mode where it's rearing to go and as such can drain the battery if not driven frequently.

 

Well, there you go then. All you guys take care. Great forum, great car.