Why does my a13 battery fall fast after reaching 20%

[Bringo]

Battery 

[theguy_lol]

Try to low every settings like

[Bringo]

It only happens when battery is at 20% but if it's above 30% it's normal

[theguy_lol]

Oh ok then its kinda normal but recomanded to low power consumption

[theguy_lol]

Graphiques

[theguy_lol]

Or even batteries consuption