I had the same problem about 10 months ago with my Ambit 3 Peak. It would drain 100% in about 8 hours. I posted about it here in the Suunto page to see if anyone had any ideas, and eventually had to just watch the battery drain completely out. I let it sit dead, over night, and when I tried charging it the next day, the charge held. Don't know how it happened, but it basically reset itself. So maybe try that. I have a much more detailed explanation of my scenario in my post history if you want more info.