Been using mine in the cold and find that it really does not like the cold weather i.e. below freezing. Works for a while but then quits after say an hour. I think it is the optional battery pack that you can buy from the company. FWIW, this is with a full charge that still shows up as 3/4 charged when I get home but does not allow the machine to turn on in the cold after it chills down. Has anyone else had this problem? As counter intuitive as it may sound, I am going to try putting rechargeables in next time as they would be in the battery compartment and sheltered from the cold a bit. Will bring the battery pack as a backup.