You remember the Germans loosing WWII? How old are you?My 06 CS's battery died in the garage after about a year and a half. They towed it in, tested the battery and replaced it under warranty. I drove it regularly and it never sat for long periods. Now I have an 09 CS and this past Friday I got into the car to fire it up and click, click, click. I had driven it the previous Monday with no issues and it sat for 3 days. In December I let it sit for 2 weeks and it started right up on my return. This time they flat bedded the car to the dealer. They charged it up and did a load test and told me everything is fine. I really don't believe that it is going to be fine. I am pretty sure it will die again. I think I remember the Germans losing WW2 because of bad batteries in the Panzer Tanks
A couple questions:
1. How far do you drive when you start the car up?
2. Do you have an underdrive pulley?
3. Do you lock the car when you store it.
If you lock the car, the alarm system will drain the battery a lot faster than when you don't. If you keep the car in a locked garage, just leave the car unlocked.
Underdrive pulley will make the alternator turn about 10% slower, so if you're just crawling around in traffic with the heater on, heated seats and rear window defroster plus the Bose radio, well, it probably won't keep up, especially if it's a short trip. Maybe you also keep your headlights on?
There was just another thread about a guy who only takes short trips with his CS. We were telling him that the water never boils out of the exhaust system and condensation never boils out of the crank case. You get that brown stuff on your oil filler cap and bits of your exhaust system can rust out. But then there's also the battery thing.
It takes about 10 miles of driving to recover from one cold start. At least that's what they used to say. I'm thinking your battery is probably OK, but it's not getting enough charging from the driving you're doing.