Porsche Repair Questions? Ask a Mechanic for Answers ASAP
You own one of my favourite cars, and I do hope to own one, one day.
I have a few cars, two of which don't get driven a lot.
I have them set up with a battery maintainer (charger) that keeps the battery fully charged. Then when I want to use the car, I disconnect the charger lead, and away I go.
This is the one I have, very reliable, comes with a lead set you can fit to the battery permanently to allow easy fitup and removal.
Hope this may be of assistance to you.
How did you go your car?
The condition you have described is a low voltage condition, very common these days.
I hope I have provided some assistance to you.