Battery trouble with S6

[Judymumu]

My battery doesn't seem to last a full day even though I paid to have it replaced!

 

[belodion]

Welcome.

Charge to 100%, use the phone normally until down to about 40%, then take a screenshot of your battery usage stats in Settings, Battery. Post the screenshot here and we'll begin to make a diagnosis. To post a screenshot, if you're not sure: https://forums.androidcentral.com/showthread.php?t=413366

(I deleted your other post since it was in the wrong place, but this thread will be enough for members to help.)

 

[Mooncatt]

The phone was released in 2005. If the battery was replaced by a third party or you bought your own, there's a high likelihood that "new" battery was old stock that's been sitting on a shelf for several years and already degraded. Even one purchased direct from Samsung would be of questionable quality today.

Also keep in mind that as apps and the OS are updated, they usually have added features, and those added features translate into more resource demands that drain a battery quicker. Even with a fresh manufactured battery, your battery life will never be as good as when the phone was new.

This may be a case of simply having your expectations set too high, and we see this sort of thing a lot.

 

[Rukbat]

If the battery is normal (made 4 years ago), go through 3 cycles of charging it to 100%, letting it run until it's at 45%, then charging it again. That may bring a little life back.

And, as belodion asked, after letting it drop take a screenshot of the battery statistics. We may see something there that you can do to improve the battery life.

Also make sure your screen timeout is no longer than 30 seconds. (That's 30 seconds after you last did anything - you don't want the screen to stay on for 5 minutes after you put the phone away.) Lower the screen brightness unless you're outdoors during the day. (I get along on 15% [with 77 year old eyes] as set by Google Assistant.) Use the Back button when you finish using an app. (I know you see YouTube videos of people using the Home button, but that doesn't stop the app from running and using battery power, it just runs the home screen. It's the wrong way to use an Android phone.) These things may increase your time between charges.

And don't use any type of "cleaner" or "battery saver" app - they cost battery, they don't save it. (They kill running background code that Android needs, making Android load it again, costing battery. Google has gotten Android memory management pretty good by now, it doesn't need any help.)