Airpod case not charging my airpods

When my airpods case drops to 5% it's stops charging my airpods. Sometimes when I open my airpods next to my iPhone it sometimes sometimes shows each airpods separate with different battery level like on is 38% and other is 42% and sometimes it's shows as one with battery level 98% and it drops down with case remaining at 5%. I have the second generation airpods with wire paired to my iPhone 8 running ios 13.3.1. Is it normal? Is anyone else experience something similar? Any help is appreciated