I have a new iPhone provided by my work, which I use for work purposes only - phone calls and SMS, no web browsing, Facebook etc. It's also my first iPhone device.

It's got great battery life; after getting it I noticed it took several days for it to reach 0%, which is quite impressive.

However after an iOS software update was applied yesterday, I seem to be getting horrible battery drain. I charged it fully yesterday and it was on overnight. No activity whatsoever on it (no calls or anything) yet this morning it was on 75%! Previously it might have gone down 1-2% overnight but not 25%.

Googling indicates other people have this issue but no resolution, apart from "wait for the next update".

Is this sort of thing normal with an iOS update? Must say I don't even notice this on my 6 year old Samsung and I thought the battery on that was getting bad.