I drive a 2005 Chevy Cobalt. I just had the alternator replaced about a month ago. I just replaced my battery about 5 days ago. This morning it is about -7 degrees outside. I went out and started my car to warm it up before leaving for work. It started fine considering sitting outside all night. I let it warm up for about 20 minutes. Once I started driving it I noticed that my display said "Battery Saver Mode". I was a little worried because this is what came up on my screen when my alternator was going out but it was also accompanied by another message (Charge saver mode). I don't think it is anything to do with my alternator. The car ran fine and drove great the whole way to work. I am wondering if my battery is bad or if it is due to the sub zero temperatures.