First times I charged Bei With this watch, the battery life was incredible - a couple of weeks. Since then I haven't changed any settings, but the charge has increased from 2 weeks to 30 hours. I've since disabled some features that Garmin says should "maximize" battery life with no improvement. Yesterday I fully charged it, used it for training and overnight the battery went from 90% to 40%. It has dropped from 40% to 30% in the last 4 hours.