I had to force the update on mine (wasn't getting the OTA update) by using Samsung Switch and doing a factory reset.
before the update to Nougat I was getting a dismal 7 hours of charge time (100% to 10%). However, after the update I am getting around 15 hours (depending on use) of battery life (measured from 730am to 1030pm).
BTW, I also switch to Nova Launcher instead of the Wiz(somthing) and that helped too!