I always have it hooked to an external battery pack. It runs all night plus with that. (10k Anker).
A guy borrowed my extra and we didn’t have it hooked to an external when he first started using it. It was real cold yet. Somewhere between 0 and -8. It was 1.5-2 hours and showing red.
In cold cold I wouldn’t expect more than 1.5-2 hours.