1. BMS1802 Introduction

Introducing the LiBat™ BMS1802, a battery management system slave module for 5S-18S battery configurations in energy storage and mobility applications. This fully digital, ready-to-use module works as part of a larger system: it measures and balances the cells of its module and reports to the master over an isolated daisy-chain line. Up to 16 modules can be chained, depending on the master (see User Manual 3.1 Battery Topology), and the modules can be placed apart with CAT5e or CAT6 cables up to 50 meters long. The board has no switch or jumper: the module ID follows its position in the chain, and the master is set in LiMon™.

Key Features:

  • Board size 125mm x 103mm
  • No switch or jumper on the board; the module ID follows the position in the chain
  • 5S-18S cell measurement with 0.1mV resolution
  • Passive balancing current up to 1A
  • Auto deep sleep
  • 1.5kV isolated daisy-chain communication line, INPUT and OUTPUT port each on an RJ45 and a 4-pin connector
  • Self powered
  • 5 external, 3 on-board NTC
  • LEDs for balancing and run status
LiBat™ BMS1802 v1.2 board, top right view
Fig.1.1: BMS1802, Top Look
LiBat™ BMS1802 v1.2 board, bottom right view
Fig.1.2: BMS1802, Bottom Look

Table.1.1: BMS1802 Technical Specifications

PARAMETER SPECIFICATIONS
Power Source Self powered. No external power need.
Power Consumption Power Down: ~0.050 mW , RUN State: ~300mW
Wake Up Trigger Master Communication Start
LED Run (module awake), one balancing LED per cell
Digital Interface 1 x Isolated Daisy-Chain, 1.5 kV isolation (INPUT and OUTPUT port, each on an RJ45 and a 4-pin connector)
Daisy-Chain Cable CAT5e or CAT6, up to 50 m
Number of cells 5 to 18 cells, at least 11 V in total
Cell Type Any battery cell in voltage range
Minimum cell voltage 250 mV
Maximum cell voltage 4500 mV
Accuracy of Cell Voltage Measurement ±1.6mV typical, < ±8.3mV max
Balance Method Passive Balancing
Balance Current 1000mA @ 4.2Vdc cell voltage
Balance Power 8W max. per cell
Temperature Sensor Type NTC, 10KΩ @ 25 °C
Temperature Sensor Accuracy ±1.5 °C (depends on sensor sensitivity)
Number of Temperature Sensor Up to 5 external sensor probes, 3 x On board NTC
Operating Temperature -20 °C to +70 °C (-4° F to +158° F)
Relative Humidity 5% to 95% (non-condensing)
Dimensions and Weight 125 mm X 103 mm X 17.8 mm, 60g