Wouldn't you just ensure the BMS's that you select are adequately rated to ensure that one single BMS can handle the maximum possible draw your system is designed to work with?completelycharged said:The issue with the cheaper BMS units, if your using them for protection is that if you have say 40A load and you have two BMS units in prallel that have FET's rated for 20A load when the low voltage level is reached and your pack is disconnected the timing between the two disconnects will not be the same and therefore you would end up with 40A trying to go through a 20A rated BMS. That is in a good case of just 2 units in parallel.