Clock falling behind - battery?
I have a 2008 M3 E92. I noticed in the past week that every morning I get in the car the clock is about 5 minutes behind. I readjust it but the next morning it is the same. About a week ago the clock and trip had totally reset themselves. And two days ago, I was installing my Valentine1 in the car and had the car in accessory (with interior dome lights on) but with the engine off. About 15 minutes after that the battery warning chime and light went on. Car started fine though. This never happened in the summer, only recently when it got cold.
Given all this, I'm assuming I need a new battery? I saw a similar "clock lag" thread on here but no resolution was ever given from the author about it..