Laptop Draining Battery In Sleep Mode with Plugged In

Hi, I have this ASUS Laptop (FX-504GD) which only 5 months old. I have sent my laptop to ASUS official service centre for twice due to the noisy fan. After I got my laptop back, I did a clean installation of window to my SSD.
After that, I realize the battery level will drop when the laptop is in sleep mode and plugged in. It did not happened before that.
Is it possible that the service centre changed my original battery? OR
I did something wrong about the setting during the installation in SSD?
Thank you.