I have noticed that my Turbo stops functioning properly in subzero temps. Today I had the bike outside during all working day, temperature being at about 8F. When I left for home, only the Eco mode worked, not Turbo or Regen. When back home, the battery did not start charging. The charge at arrival to work was 88%, which had dropped to 83% during the day. This has happened to me before. So, I recommend taking the battery inside during cold days, if being outside means several hours.