BU-502: Discharging at High and Low Temperatures ? Battery University...Specialty Li-ion can operate to a temperature of –40°C but only at a reduced discharge rate; charging at this temperature is out of the question...
Same here since I have seen typical car starting batteries give up even in -20 weather. So -40 will do some real damage unless someone keeps a block heater. Some of that heat will maintain some level of function within the battery.-40C is -40F That is cold, never seen such in my life. Hope I don't.