I have a bank of 3, 230ah batteries made of prismatic batteries (each battery has 4 cells). The cells within the battery are staying balanced, but one of the three batteries is now staying about 20% out of balance with the other two. I have the batteries wired in parallel to buss bars. In the picture you can see the green negative wires going to a buss bar in the back connected to a smart shunt. The red wires connect to the positive bus bar. All of the wires green negative wires are of the same length, and all of the red positive wires are of the same length. Is there anything I can or should do about this, or is having one battery out of balance the price of using a parallel bank of batteries?