After installing iOS 10 Beta 3 my battery runs down extremely quickly on my iPhone 6s Plus, My iPad Pro and my Apple watch. I did not have this problem under the previous betas.
Beta/Upgrade survival Training;
Heat/Warmth/Battery issues POST Beta/IOS upgrade. Here's the equivalent to "Take two asperin"
Goto Settings -> General -> Reset -> Reset network Connections AGREE to doing this
Need to resetup - ALL Wifi connections & VPN connections - however - this WILL solve things.
I had a funky issue - Wifi was working FINE - it never connected my Cell - I had to reset network connections then re-boot the phone, then it connected to AT&T network