Amazfit Watch faces

I noticed when creating the Watchfaces that you can create virtually any number of stages of the battery gauge. In operation, however, it is the case that the clock internal battery indicator and the Watchfaces does not cover. For example, the internal display shows 18% - if I define the display in tens even in the Watchface, I get three bars displayed instead of two or one ... If this is due to the inaccurate display of the clock itself, there are other steps for viewing the watchfaces or where is the cause to look for? In principle, it is not a huge problem, but instead of getting an accurate indication of the battery level, the display is unfortunately only for guidance

0% is one, so 10% is two, 20% is three

You need to use 11 pictures to display 10 levels correctly