08 cts di awd yesterday I got in my car after work and it said battery saver activated... drove home everything was good... went to drive to work at 3pm and battery was dead. I had to use the key to get in. When I opened through door nothing came on and the keyless nob thing would turn. Does that sound like a battery issue or alternator... will be going to get battery and alternator checked tomorrow. I also plan on putting it on a charger overnight