Hmmm... I'm balancing right now without charging at the same time. But I'm balancing for 1,5 hours and it's still; led number 1,2,3,5 are constantly blinking and number 4 is off. I'm getting scaried for that LiPo TBH
EDIT: Or is the 4th cell of LiPo defect? I dont think so because the total battery voltage after charging is 21.007 volt and it did his job good yesterday.