Planet-9 Porsche Forum banner
1 - 1 of 1 Posts

99 Posts

There are two key things to take away from this data:

1. You should NOT leave the key in the ignition switch when you park your
Cayman. It draws 1.7 amps (after time delay loads shutdown) with the key in the
ignition switch. This is about 100 times the load when the key is removed - and
enough to drain your battery within a couple of days! Note that if you listen
carefully, you can hear multiple solenoids and/or relays energize when you
insert the key without turning it. These things take a LOT of current. Note that
1.7A this is more current that the Boothe Design and Deltran battery maintainers
can put out. So with the key in the ignition switch and one of these maintainers
connected, your battery will still drain!

2. It does not matter whether or not you lock the doors when you leave the car
in storage with the key removed. The idle current once everything (interior
lights, dashboard, etc.) times out and shuts down is about 15 milliamps (0.015
amps) - independent of whether the doors are locked or not. A heathly and fully
charged battery should be able to easily support this load for several weeks
without problems.

Here's a summary of the steps I took and the measurements using a high quality
digital amp meter in series with the battery. Note that current readings vary up
& down by a several 10's of milliamps when the various electronic systems are
active, until they eventually time out and shutdown from lack of door lock, door
switch and ignition activity. This is likely controlled by timers within the
various electronic control modules and/or CAN bus commands to shutdown these

One thing that I have not measured (yet) is how much below the ~15mA level the
load drops after 7 days idle time. This is when the Cayman shuts down the
receiver for the remote key locking system. One can assume this load drops even
further after the 7 day timeout.

Amps Cayman state


0.12 Car locked, boot & trunk closed

0.05 Same - after a few minutes (load timeout & shutdown?)

4 Unlock doors - interior lights turn on

4.8 Open drivers door

5.2 Sit in driver's seat & close the door

1.8 Lock doors - interior lights fade out

5 Insert key in ignition switch - interior lights still on

8.5 Turn ignition switch on without starting car

2 Ignition switch off but still in switch - after interior lights fade out

4.7 Remove key from ignition switch - interior lights back on

5 Place key back in ignition switch without turning - interior lights on

2.2 Key remaining in ignition switch, off, after interior lights fade off

1.9 Same - after instrument panel shuts down (odo, speedo, etc off)

4.7 Remove key from ignition switch - interior lights back on

1.1 Exit car and lock with key remote - interior lights faded off

0.1 Wait a couple minutes (more load timeout & shutdown?)

0.015 Approximately 20 minutes after locking car

(and continuously for the next 24 hrs)


0.015 Key removed, doors unlocked, after a few minutes and for the next hour


1.7 A few minutes after placing key in ignition switch (without turning),

and closing doors - interior lights have faded & other loads time out

(and continuously for the next hour)

FAQ Information:

This FAQ was written by L8Apx

Last Revised: December, 2007
1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.