when you press the button with the three batteries in the hub,all 3 sets of lights will come on to tell you the state of charge of each battery and after a few seconds they will go off this is quite normal
if you then plug in the charging lead the hub will determine which battery has the most remaining charge and then the battery that is being charged will start its lights to cycle until that battery is full,the other two will be off, then after the first battery to be charged is full it will display 4 steady lights,and the next battery will start charging, and so on, after all the batteries are fully charged all 4 lights for each battery will be lit ,and will stay on to inform you that they are all fully charged,until you unplug the lead to the mains from the hub then they will all go out