Ok, so when my brightness is on 50% or less I can get 3-4 Days out of my Note4..
So I decided to see how long it would last on Full Brightness..
At 15% once I turn on Ultra Power Saving mode can then get a further 2 Days out of the phone..
Not Bad at all.... Gonna use phone on about 80% brightness as I want to enjoy the screen..
And the fact that I can get a full charge in about an hour is a big plus..