Scooter Talk

Hi folks,just joined,so this is my first post.basically my sons scooter has a problem.basically when giving it full throttle,the scooter will cut out,and won’t work again until it’s charged again up to 5 bars,even though there is 4 bars still on the display.any ideas.battery is showing 37v on my multi meter,so wondering if it’s a few bad cells or throttle problem maybe.