I have one, the batteries last several hunts but I don't run the fan all night generally. Few hours at night and then in the morning for awhile. It heats my 200 sq ft tent very well without the fan but the fan is nice. They are supposedly very safe but I still only run it part time, plus it'd be too hot running all night. It's been a great heater for me. I have not had mine at 8000ft though.
