Hi, i just baught the bluetti ac200p and tried to charge it with ac adapter on a 2000w inverter that is pluged dirrecly on my car batterie
Thé bluetti is charging at 350w but the ac adapter Green les turn to red and is making a little sound.
Im not shur if it’s normal or if there is something to worry about.
If it’s like the charger on my EB70S, the red light means its charging (turns green when its done) and the little noise is the fan in the charging adapter keeping it cool. Both are totally normal with mine, anyway. 
Please make sure you are charging with a pure sign wave inverter.
If you hear a buzzing sound and are unsing a low cost modified sine wave inverter then yes, I would be concerned.