So I have the Note 9 and recently I have noticed that the battery is draining quicker than usual. I tried to optimize the battery but it didn't work. When I look at the diagnostics it says the battery should last 16 hours but currently I have 73% and it says it should last around 12 hours I think, but it's hard to believe that 73% can last around 12 hours. I want to know if there's another accurate way to see how the battery is doing. I'm not sure if my battery is faulty or if it's a software issue but I would just like to make sure and check. Can anyone help me on what I should do?
Usually it's apps or usage (SOT, gaming, video streaming etc)
But you should check your app usage in the battery settings to see what exactly is consuming the most battery.
Also you can check your lifetime charging cycles by downloading Samsung *Info* from the app store. Once in app swipe right until you reach the "Personal" menu. If you have really really high charging cycles the battery potentially is near end of life as most batteries claim 500 charging cycles for the lifetime of the battery. Your charging habits can play into this situation. But I would like to say that theses many variables to your situation beside what I've described. Search the Galaxy note 9 Reddit for battery issues, or battery optimizing and you'll find some info. You can also try XDA or possibly Telegram.
Have you confirmed your device is currently up to date to the latest software?
Give this link here a shot giving additional information on how to increase your battery life:
You also have an option to put apps to sleep when not in use.
Follow this link: https://www.samsung.com/us/support/tip/TIP00080625/