My mate got his Apple Watch Friday. While it's been fine with the battery life, about evening time yesterday, it started to drop battery charge quickly (from 40% to 10% in an hour with little activity) Today is the same. Not much activity, no glances bar the stock ones, and using intermittently. Took off charge at 7am and now at 40%. The interesting thing is, the usage says the standby time is the exact same as the used time. In contrast, I've been using mines a lot today to control music, reply to texts. Read emails etc since 7am and mines is 78%. Is this a defect? Anything I should try?