Jk bms rs485 The interface comes with a 4 pin plug, This BMS port labeled RS485 is a 3 pin port, Next to the RS485 port there is a 4 pin port labeled GPS, The datasheet give a lot of info; Also the following text; RS485; From here, we will list the most used BMS'es for LiFePO4 batteries. Most Used BMS for LiFePO4 Battery Cells 1. JK smart BMS.