Hello, I have a 2001 740il and the battery light came on about a week ago but upon checking the alternator I found that it was still charging. Two days ago the battery went dead so I checked the alt. again and noticed that it actually charges the battery for about 10-15 mins until the car warms up. Once the car warms up, the alt stops working. I checked to make sure the alt. chamber was getting coolant and it is. So does this mean the alt needs to be replaced or is there some other problem causing the alt to stop charging after 10-15 mins.