Oh Dave I feel so used. After we have warned about this so many times, you a frequent poster and reader went and did it (Porsche even warns you in the manual on page 236 of the '06 manual)...but I'll give you credit for confessing. Also consider this from the manual "After the battery is connected or after an completely discharged battery is charged, the
multifunctional
PSM light lights up on the instrument panel and a message appears on the onboard computer to indicate a fault. This fault can be remedied with a few simple
steps:
1. Start the engine.
2. With the vehicle stationary, perform a few
steering movements to the left and right and
then drive a short distance in a straight line
until the multifunctional
PSM light goes out and
the message on the on-board computer
disappears.
3. If the warnings do not disappear, then:
Drive carefully to the nearest qualified
specialist workshop.
Have the fault remedied.
4. After the warnings disappear, stop the vehicle
in a suitable place, and perform adaptation of
the power windows.
To do this, close windows once with the rocker
switch.
Press front half of rocker switch upwards again
to store the final position of the windows in the
control unit."
Rapid charging can shorten battery life but I'd guess you will be o.k. if you take care of the battery from now on.