Oh, maybe batteries is draining because 1. You are using your phone for long time continuously. 2. Do not play or use phone while charging. 3. Use branded charger the specified charge for your phone. 4. Do not use phone when it's too hot. 5. Put low use app in deep sleep.
One of the reason for losing battery is background app. So for that go to developer mode. Scroll down. Enable background limit to 4 process .
