So our bitter cold has taken its toll on my 12v battery. It is going on 6 years old, and without warning, today when I went to leave from work, my FEH would not start. All this past week has been relatively short trips in extreme cold. I don't think we've had one day above freezing in at least a week. This evening when I went to leave work it was about 20F and the FEH refused to start. My battery was reading 8 volts. I guess this explains my drop in mileage the past month or so. I had felt the drop was more than just bitter cold weather, and now I guess I know why. Its been trying its darnedest to charge that battery. So, I took this opportunity. I had been thinking about replacing my 12v with a lithium automotive battery as the efficiency of a lithium battery is much better than a lead acid battery. I took the plunge in the name of science. I just ordered the battery online. My hope is that the lighter weight combined with higher efficiency of the lithium cells over lead, that I may see an uptick in mileage.