My AC200 has been working great, use if for camping (Running fan, TV and Morning Coffee) When I turned it on to use was showing 100% Battery. Within 10 min it dropped to 0%. I charged it and went back to full 100% in 10 min of charging. Now when battery drops to about 87% shuts off and its 0%
Try charging it to 100% let it sit there for half a day and drain it slowly. Maybe the battery gauge is not well calibrated. If it is still like what you said, you should probably contact bluetti for warranty service and see fit they have an idea. Something may be wrong with it.
Sorry for the inconvenience.
As the @snowstorm said, please try to fully charge and discharge it to zero. If it doesn’t work, please contact our customers service. We will help you to solve the problem.