3 ms·My problem is that if it's also a sleep tracker. When are you supposed to charge these things?by josu 12y agoMy problem is that if it's also a sleep tracker. When are you supposed to charge these things?imajoo 12y ago1.5 hrs to full charge, 30 min to 80% charge. I'd charge it while making breakfast.josu 12y ago>30 min to 80% charge That's impressive. But why does it take 60 minutes to charge the last 20%?kevingadd 12y agoTo put it really simply: Batteries are nonlinear. Charge/discharge rates vary based on the current amount of power stored in the battery.josu 12y agoThat makes a lot of sense, thanks.deleted 12y ago[deleted]