I have a solar panel system with 4 x 150W panels (Voc 22,3V, Isc 9,1A) in series and 2 x 12V AGM 140Ah batteries in parallel controlled by a Bluesolar MPPT 100/50. Now I'm about to extend with 8 more panels of same type and 6 more AGM batteries of same kind as the previous ones. My plan is to make it a 24V system instead and setup the panels as 3p x 4s, thus keeping the panel voltage but increasing the current. I'm wondering is there a way I could use my around 2 years old batteries in this setup or do I need to leave them aside. Can a balancer help me here, I don't fully understand how it works, what would the wiring be? I would like to make a 4p x 2s batteries setup, but if I can't use them I will need to go for 3p x 2s and leave the old batteries to setup a separate system. I would really like to use them and have the capacity.