I think I've found what was draining my battery in the background. Just by now I was messing around in the settings and found that Background App Refresh was enabled for ALL my apps, and I always let this option off to preserve my battery. I think it turned itself on or something cause I remember letting it off. So do you use this option?!I had no problem with Beta 7. It only started today. I will monitor it and will take action over the next day or two if it actually presents an issue by reduced battery life.