Just finished a big discussion about this stuff at Battery and Solar Panels for 12V motor controlled by Photon
I think the LiFePO4 batteries charge differently. http://www.powerstream.com/LLLF.htm
I know you can get LiFePO4 charge balance boards at https://www.amazon.com/Battery-Balance-Charging-LiFePO4-Lithium/dp/B01E3A0S04