Does This Kill The Battery?

Read through most of the threads on dead batteries but did not see this question answered. My 6 month old Cayman battery was completely dead this morning. I drove the car the night before, so I know I did not leave it sitting too long. Also, the radio was not left on, the door was not ajar, the directional was not left on, the lights were not left on. I did not have any accessories plugged in, but I did have my cell phone power chord plugged in under the dash (phone was not attached). Finally, I left my key in the ignition in the OFF position. So, my question is, does anyone know if it drains the battery if you leave the key in the ignition in the OFF position, and/or if you leave your cell phone power chord plugged in without the phone attached? If the answer is yes, this issue must be unique to the Cayman because I never had a problem with my Boxster battery in the 5 years I owned the car.

I would not think that either would drain the battery, but the car might not have gone into sleep mode with the key in the ignition and that would drain the battery faster. Only one way to know, charge up the batter and try each item separately until you find the culprit.

The owners' manual says "Do not operate additional accessories for more than 5 minutes when engine is off" and this " In order to avoid unintended battery discharge always withdraw the ignition key when leaving the vehicle ." So it could be the key since the charger without the phone surely is not "operating".

Thanks for the quick reply. I will modify my behavior regarding leaving the key in the ignition. If the problem persists, I will bring the car into the dealer and let the forum know.

I would think it could be either that might be the culprit of the battery discharge since you shoulbn't leave either in. But my question for you is, ARE YOU CRAZY? Why would you leave your key in the ignition? Even in the garage that is inviting your car to get stolen. Haven't you seen "Gone in 60 seconds" (remake)? That frequency finder does exist. I would certainly stop that practice. Good Luck!

The cellphone charger could definitely be the culprit. Even if you don't have a phone plugged into it, it's still drawing a small amount of current. Same thing goes with leaving the key in the ignition - various electronic systems in the car (i.e., 12V power ports and other things) draw current as well. I'm just surprised that the battery discharged overnight. There have been times when my trunk lid popped without me knowing it and the car has sat all night with the interior lights on, and I haven't had a dead battery yet (crossing my fingers). I'd also get the battery checked out too.

This is not normal - the battery is rated at 80Ahr - lets assume it gets dead at 50% capacity - that would be 40Ahr - if the car was unused for 24 hr, that would be 1.66A of current flowing from the battery, which to me is a fair bit for a car that is switched off. One of those days I hope to measure the current flowing from the battery under different conditions, but I suspect there must be numbers published by Porsche in one of their shop manuals - does anybody have access to those figures ?

Well, my car started right up this morning - once I found where I left my key. So, it appears leaving the key in the ignition overnight is a significant drain on the battery. I say significant because my battery was so dead yesterday that Porsche Roadside Assistance could not get the hood open initially and actually had to let the battery charge up a few minutes before there was enough juice to pop the hood. I too would sometimes leave the dome light on overnight in my Boxster and never had a problem. I can't imagine that leaving the key in the OFF position draws more current than the dome light. But then again, I am not an electrical engineer. By the way, in my opinion, if Porsche didn't want us to leave the cell phone charger plugged in when we turn off the car, they should not have put the outlet so far out of reach from the driver.

Cayman Battery/Key Funny this should be brought up. Last year, I washed my Cayman and began waxing it. Long story short, it got late and I figured I would finish the wax job in the morning. I, too, left the key in the ignition over night since I still needed to finish the wax job and needed the key to move the rear fin up and down. The car was almost dead by morning. It totally baffled me since I have never owned a car that would die like that. So, yes, leaving the key in the ignition drains the battery, and at a pretty good clip. I have not had any issues since. Nice to see I wasn't the only one.

You have to remember that there are a number of factors that effect the state of charge of the battery including traffic density and speed limits that all reduce the engine speed and, hence, the generator output. If you have a slow, short commute it is unlikely you ever have a fully charged battery which many have seen when they plug in their battery tenders and find out how long it takes to achieve a fully charged state. It is something we take for granted but with the newer Porsches, the large number of electrical loads has markedly increased the demand for electrical power. Therefore it is not surprising to see the key or some other electronic device completely drain a battery that is probably not in peak condition. Best solution? A nice fast long drive.

My commute is 30 miles (45 minutes) each way, and I have put 10,000 miles on my car in six months. However, Saturday I probably drove only 20 miles locally before putting my car away for the night.

It is almost certain that leaving the key in the ignition caused your dead battery. The owners manual warns not to do this. Someday when things are really quiet, get in your Cayman, close the door and slide the key into the ignition without turning it. You will hear a *very* significant set of clicks or clunks. I believe these to be electomagnetic solenoids releasing the steering wheel lock and possibly another one in the ignition key unit itself. (It sounds like two distinct solenoids operating) These buggers take a lot of current to hold open. I'm not surprised that they would drain a battery over night. If you are in the habit of leaving keys in the car while in your garage, just pull it out of the ignition switch and lay it in the boot around the base of the shift knob!