My car seems to create randomly occurring gremlins while I’m charging my AC200L. I have found my rev counter and fuel gauge completely stops working on some occasions, and on others i get 3 warning tones sounding every minute or so as if I’m low on fuel. Is the Bluetti putting too much strain on my car battery?? The problems disappear once I stop charging the Bluetti and everything returns to normal. The Bluetti is pulling around 100w from the car.
It would assist your answer if you note your vehicle type, what the charging source is etc… 
100W @ 12.8VDC is 7.81A which should not interfere with vehicle operation. If your vehicle is “aged”, are the start battery and alternator in good order? Have you checked the voltage when charging the AC200L in the power cord. (you may need to open the plug to do this, or use a short extension lead modified to access + & -. I use one with staggered bare wires to clip my multi meter on carefully to avoid shorting. (cig plug one end, cig socket the other end.)
The car is a Vauxhall (Opel) Insignia, 1.6 Elite and diesel. Charging source is the 12v cigarette socket locket at the back of the centre console which is primarily used for the rear passengers.
@AdamB May I know how do you charge it? Is it through the car charger (cigarette lighter) or by using the AC output socket of the inverter inside the car?