Not very reliable in Winter Vacation [EDIT]

Winter holidays, on the slopes around -6 degrees outside. In the middle at the first exit I heard the GoPro Hero 4 beep. Battery empty. Less than 5 minutes I was able to record with this battery. Battery was on the eve at normal room temperature (about 21 degrees) fully charged. Thus, the thing comes back. Have now decided anyway for a GoPro BacPac.

EDIT 19/01/2015:
As you can pursue in the comments, the customer has very quickly put in touch with me and now I got a new white battery sent. This has under normal temperatures sufficient battery life of about 1h 20min (1080p 60fps Super View). In mid-February, it goes back to the ski resort and there I will then test the WEISS battery, adapt this review accordingly. For now, it remains here at 2 stars, because this review was the basis, how does the battery in the winter holidays or at low temperatures.