Why my battery is decreasing while charging?

I have Recently changed my battery. When I went to bought new one the new battery was showing only 2.2 volts so he started charging the battery and when it was 3.8 volt my phone starts and it shows 17% battery when I came back to home and started charging my cell phone it was continuously decreasing the battery phone was still charging what is the issue can you please help me.

I have no original charger I am using a Vivo charger with 5 volt and 1 ampere output.

And when I am charging my cell phone while switch off it is increasing the battery percentage.