Hi @Maxwell , one thing you can do is to identify if its a battery problem or a third-party app is using your resources. First charge your phone to 100% then let it sit for an hour without using it. After one hour check your battery percentage. The result of your battery after an hour is your baseline.
After that,charge it again to 100% with out using it. When the smartphone reached 100%, open your phone in safemode. Check the link on how to run safemode on Samsung S5:
When your phone is on safemode leave it again without using it for an hour. After an hour check the battery percentage again and compare it to your baseline. If you see a significant deference on the results. For example a 10-15% difference, there is an app or software that is consuming your battery in a fast rate. You can do an isolation test to determine what app is the one causing the problem. You can try disabling an app just to determine which app is causing it.
If the results of the baseline and the safemode result is the same. You can try using a different battery to determine if the original battery has a problem. Again using the same method at 100% , use the other battery and leave it for an hour. Check the result again by comparing from your baseline. By this time you will know what caused the problem. If the other battery has a much better result from your baseline, you may have to replace your original battery.
Have you tried turning battery saver on? Also try to turn off unnecessary applications which are known to destroy your battery if they are left turned on. That is usually the biggest problem, because people forget to turn them off. Also check your Wi-Fi, bluetooth, turn all of that off. Clean your phone, any excess data, clean all the trash and it will last longer guaranteed. Hope i helped