The screen on my original Galaxy Note 4 broke and insurance provided a new phone. Even before the Marshmallow update this new phone would not hold a charge very long, and while plugged into my car charger using Waze or just making calls the phone would discharge faster than it was charging. Previous phone was fine. I used the battery from the previous phone and there is no difference. I am lucky to get 6-7 hours normal use (with Waze off.) Battery drains super fast and is very slow to recharge-- two hours in a wall charger might add only 20%.
There is nothing else different in the way I am using it from the previous phone except I have turned the screen brightness way and often turn off GPS and WiFi down to try to preserve battery life. Seems to have little effect.
A colleague has the exact same problem. What is a real-world solution? Apparently there is a serious problem with the phone itself. I need this for work and have to do something ASAP.