I always charge my istick at 60% till 90%.So now as i was charging it wasnt charging about that 60% indication. Sometimes it flashed to 90% and then back to 60%. Is it a common problem for it to misread if the other indications arent used? Have i broke the indication the way i am charging? Should i let it to fully discharge as i saw that i should charge from 40% to 80% i never done it.