Not always , as a matter of fact I have a DNA 200 that was at 100% battery. I ended up leaving the house and left it plugged in to a usb charger for about 24 hours. came back home to notice my battery was at 80% . Cell 1 3.86v , cell 2 and 3 both at 4.2v. kinda sad the board sucked down 0.4v at an idle while hooked up to a charger. Also noticed that the boards only really want to balance charge when the charging screen brightness is turned down to 0%, at 60% brightness it goes idle and stops charging when 2 cells hit 4.20v