REC BMS Master – Slave configuration is suitable for higher voltage systems (up to 800 V) or for 48 V in parallel connection. It allows to connect up to 240 cells in series with REC 2Q BMS as Slave units and it is compatible with all REC BMS products. Master unit is also compatible with variety inverters for use in Energy Storage systems.

REC Master unit

REC BMS Master 9M:

  • Li-PO, LiFePO4, LiFeYPO4, LiCoO2, LiMnNiCo and LiMnO4 Lithium-Ion chemistry
  • Master + max 15 Slave combination (max 240 cells)
  • compatible with all REC BMS units
  • single cell voltage measurement (0.1 – 5.0 V, resolution 1 mV)
  • single cell internal resistance measurement
  • single cell under/over voltage protection
  • SOC and SOH calculation
  • over temperature protection (up to 3 temperature sensors per Slave unit)
  • under temperature charging protection
  • passive cell balancing up to 1.3 A per cell with LED indication
  • shunt current measurement (resolution 10 mA @ +/- 300 A)
  • 3 galvanically isolated user defined multi-purpose inputs/outputs
  • 4 programmable relays (normally open and normally closed option)
  • 12 V galvanically isolated supply (10.5 – 15 V)
  • galvanically isolated RS-485 and CAN communication protocol
  • error LED + buzzer indicator
  • internal battery powered real time-clock (RTC)
  • PC user interface/Wi-Fi module for monitoring, changing settings and data-logging (optional accessory)
  • hibernate switch

Included accessories:

  • connection cable Master to 1st Slave BMS
  • Master power supply connector (optional with cable)
  • termination plug/connector for last BMS unit in chain


  • length = 98.5 mm
  • width with mounting pads = 190 mm
  • width = 165 mm
  • height = 38 mm
  • mounting hole diameter = 4.5 mm
We suggest M4 screws for mounting.

Master to 2Q BMS Slave connection instructions: