A few days ago, I installed the latest iOS 9.1 public beta on my iPhone 6. It's a bit risky, I admit but I like it.
My iPad 4 and iPhone 6 both got iOS 9.0 (public beta) a few weeks ago and everything worked without any problems. When iOS 9.1 public beta came out, I was eager to try it out and discover what was new.
Overall, nothing much compared to the prior version 9.0 beside a major issue with my iPhone 6: Overheating issues!
On the first night, I plugged in my iPhone as usual and in the morning, discovered that it was warm. Usually, the iPhone is cold as ice, even after having spent the night on its USB charger (the stock one from Apple). So I rebooted the device, assuming it was a glitch...
Later on that day, I found out that the battery was draining really fast. Usually, the battery will last easily 2 days on a single charge but I have kept the old habit on charging it when going to bed. On a normal day, the battery level will drop to 75% at most. But after iOS 9.1, the battery level was already at 40% only a few hours after disconnecting from its charger.
Again, I rebooted the device, re-check all settings, closed all apps from the app switcher... I tried everything and I was considering reverting to IOS 8.4 until the official 9.0 comes out.
On the second day, after a second full-night charge, the iPhone was still warm and the battery level was at 45%. A real nightmare was at the door...
Again, I reviewed everything, all settings, rebooted many times with no luck. The battery level was dropping fast at a rate of 1%, each 2 minutes...
So I tried something different.
First, I activated the "Low Power Mode" and switch back to the "Normal mode" in the general settings (available on iOS 9.x only).
Then, I deleted the Apple Beta Certificated from the General Settings expecting an "update" reverting me to the official iOS 8.4. Nothing happened actually so I decided to re-install the Apple Beta Certificate to get the next iOS 9.1.x public beta version just in case. I was willing to wait another full day, preparing a full recovery to iOS 8.4 if the problem would still show up.
It's been 24 hours since then and the overheating issue seems to be resolved. I don't know if flipping the "Low Power 'ode" did the trick or simply re-installing the certificate for the public beta did the job but something got fixed along the way.
One thing is sure, rebooting the device did not fix anything as I had already rebooted many times. For now, I can assume that one of those two operations fixed the overheating problem on my iPhone 6.
As a side note, nothing happened on the iPad 4, still working like a charm with iOS 9.1 public beta.
Did you fix your overheating problem with this tip? Let me know.