I have the MyGreenVolt app (free). If the car is off, not plugged in, the battery temp gets very cold. I can't remember exactly, but I believe I have seen the battery at 20 degrees in the past. Given the chance to warm the battery it warms to 50 degrees. I would guess that is the temperature it is happiest at then according to the engineers. I can't remember the top end number, but I know it is at least 70 degrees. I should note, I have a ERDDT defeat switch and have had no problems with the battery being too cold over the past 4 years that I have had the switch installed. Except for my recent temporary, self-correcting glitch you saw on my other post, cold isn't a problem. Eric Belmer (Facebook, over 425k mile Volt), as his battery aged, he gets the message that "Propulsion power reduced" (or something like that) and the engine kicks in to help the battery. We haven't gotten this message, so I don't think we are in the same boat. Different issue. The running of your engine for .03 to .10 gallons is the typical level for warming the engine if it kicks on for any reason. I really like the idea of the hood switch toggling the engine and it stays on to complete the warming cycle, only because there is no error message.