I have a 2006 Volvo s60 2.5t with 28000 miles on it. Recently (over the last 2-3 months) i have had some battery issues. I park the car outside in the driveway (cold weather, about 30 degrees farenheit on average and as low as 20 degrees overnight). On two occasions i have had a dead battery and needed to get jumped. other times i have found the engine takes a few more times to turn over on start up. I have taken the car to my local mechanic (where the battery had also died). They tested it and found no problems with it. it is the original volvo factory battery. There are no notification lights or messages on the dash panel either. I do have 2 items plugged into the cigarette lighter styled power connections (radar, sirius) but those are suppose to automatically turn off when the car is shut down (no power from them either).

Does anyone know what the problem could be?

 

If your car is a 2006 then it "seems" too early for your battery to be toast.....

Sounds like you have an electrical drain somewhere if your battery is testing fine but still dying after sitting for short periods.

The fact that the engine has to turn over a few more times to start up does not sound like a battery issue.

 

You probably have a draw somewhere.

I was having the same issue with my Camaro. Its perfectly fine in the warm months, the cold just makes it die much quicker. You should check out the charging system as well, but that probably won't be it.

 

One idea that may be useful. You don't drive very far, do you? I don't know how far you drove to t he mechanic's for the test, but maybe it charged sufficiently on that trip. Have you fully charged it (read the manual--there is a procedure) and seen how it performs? Just sitting discharges batteries, and short trips don't much help.