Just added to US3000C batteries to an existing pair of US3000C batteries. Started balancing operation all commss cables removed as well as lines to inverter. balancing started as expected but after a few hours the 2 existing batteries continue to show discharging but the new batteries are in standby. Restarting the balancing procedure shows that the new batteries are still on 3 LEDs whereas the old batteries are on 5 LEDS. Balancing continues for a few minutes and then they go into standby again. Is this normal and do I just have to wait overnight for balancing to complete. Or is there something I’ve missed.