Yes, as others have noted this is normal, I run 4 x US2000 Plus batteries. If you run the BatterView software with a console cable connected it will show the battery changing modes when the leds go out, i.e between charging, discharging and idle. Sometimes it might turn 2 batteries in the set to idle at night when there is low load and the lights will go out on those units, just normal part of the BMS operation by the looks of it.