What is draining the battery?
 

I know that it is an accepted thing that when you let the boxster sit for a few days the battery dies, however I am a little tired of getting new batteries.

I went to the car this am and all I heard was click click, If it sits for more than 2 days, worse if cold outside, the battery barely starts the car.

What is it that is draining the battery? The CPU? Alarm?
I have seen those battery disconnectors that disconnect but allow a minimal voltage to keep the radio and CPU memory active. Would that work?

The list of what can be drawing power is almost endless; the alarm system, the stereo, GPS, radar detectors, etc. etc. Most don’t understand that something like a cell phone charger, even without the phone attached, still draws current.

Best way to sort this out is to disconnect your + battery terminal (be sure you have your radio code handy) and put a digital volt meter (set to measure current) between the cable and the battery. Then pull one fuse at a time from the fuse panel and watch the current draw change. This will tell you what circuits have the drain on them, and identify the level of drain for each. The basic car electronics (alarm, immobilizer, computer, radio and clock) should show a total draw in the milliamp range or so; draws beyond that are where your problem lies………………

I would add that I have a 2001 S, and have let it sit for 2 weeks and it started right up. So what you are experiencing is probably not normal.

I've started using a battery maintainer now that the weather has turned.

I hated dealing with parasitic drains- I would also look into a "battery brain".

A good battery and voltage regulator
 

and my no-modifications or additions Boxster sits for 3 weeks and starts right up in normal temperatures.

Ask yourself what wasn't on the car when the factory delivered it and first suspect that. Then follow JFP's advice on testing circuit by circuit for the abnormal drain.

The Boxster is smart enough to turn lots of things off as time goes by to save battery drain...if it is stock and everything is working right.