Battery drain when off

My garmin Edge 530 is losing approx 1.5% per day when off. I use the power off button and it is not in sleep mode while doing this.  One time it lost over 10% in 30 minutes. The strange thing is it drains faster when off and when I'm choosing the option vs when I'm using it as a GPS on the bike the battery drain is reasonable. Anyone know how to solve or experience anything similar?