Today my roadster spent a good part of the day outside. The temperature was around -11C. When I got into it this evening, the No Regen light was on and I assumed that this was because the battery was too cold to put electrons back in. I drove home, about 25 Km, highway and still the Regen light was on. In the past, when I have seen this happen it seems to me that after 10-15 minutes of driving the Regen would be back again. As I got home I decided to check the temperature of the battery with the OVMS module. It was at +7C. I plugged the car in and it said Heating battery instead of charging. I have never noticed that in the past (but maybe I never paid attention). After about 30 min I checked it again and the battery was at +13C and still saying Heating. Now, after about 45 min it financially has started charging the battery and the temp of the battery is at +12C. All seems bizarre. Why would it be a degree colder than 15 minutes ago? Does anyone know what the cutoff battery temperature is for the car to use Regen? Seems to be around +13C or so. So strange that I would only have noticed such a case on my 3rd winter!