At 15% Battery not usable anymore

Hello,

Why is the watch at 15% already showing " Low Battery" and stopping Pulse Ox meassurimg ?

Also i have deactivated all the time: Bluetooth, Messages,  Weather, Music and the Watch burns 50% Battery in 7 Hours over Night, this cant be normal ?

And why is the Alarm Clock only Vibrating once, but the Timer is vibrating until i deativate it ?

Greez , R3c Upside down