When I unboxed my Microsoft Band, it had an 80% charge. I slept with it that night, and it was at 80% in the morning. I threw it on the charger for 30 minutes while I showered, and it was still at 80%. It seems like it really likes 80%!
I wore it that day and slept with it again and it was still looking like the battery was near the top, so I decided not to charge it in the morning while I showered to see how long it would go. I wore it that day, and slept with it again. It stopped recoding my sleep about 3am.
So I put it on a charge at 6am when I got up, and 2 hours later when I checked, it was at 80%. 80% again. I was wondering if it even had 100% as a charge metric. But, 15 minutes later, I finally got to see 100% charge. Now that it is fully charged, I’ll see how long I can wear it before it dies. I suspect that it will 2 full days and nights. But even if it doesn’t, it certainly can handle 1 full day without issue. Not bad at all!