The Wattius wBMS-MX is a distributed Battery Management System developed to work with high-voltage batteries up to 800V. The system has been designed to meet all relevant industry requirements such as IEC61508.

This system is composed by the BMU (Battery Monitoring Unit) and CMU12s (Cell Monitoring Units, each for up to 12 cells). Each BMU supports up to 48 CMU12s. Multiple BMUs can be connected in parallel without additional hardware. The system automatically handles multiple string connection and provides a single control interface with the inverter / charger.

Each CMU12 can monitor up to 12 cells with total maximum voltage measurement error of ± 1,5 mV, and 3 external temperatures. The BMU provides multiple configurable I/O options, as well as CANbus, Bluetooth and USB interfaces.

  • Each CMU12: up to 12 cell measurements with ± 1,5 mV max. error.
  • Up to 48 CMU12s for a single BMU.
  • Autonomous parallelization of multiple battery strings without additional hardware.
  • Ultra low power mode (< 15 mW).
  • High-precision SoC algorithm.
  • Up to 300mA autonomous balancing.
  • EMC CE Class A & B compatible.
  • CANbus, USB & Bluetooth Low Energy.
  • Real-time logging of events, alarms and data to micoSD card.
  • Monitoring, configuration & analysis with free wBMS-Toolkit PC software.
  • IEC61508 compatible design and components.
  • Internal extended diagnostics and safety-critical redundant systems.
  • Cell and relay open-wire detection.
Power Supply

10 – 36 Vdc

< 15 mW in deep sleep mode

Independent input for output supply

Maximum system voltage

800 Vdc

Supported CMUs

24 CMU12s for each wBMS-MX BMU

Current sensingExternal 0 – 5 Vdc hall current sensor. < ± 0,1 mV.
CAN Interface

CAN bus 2.0 A/B (Up to 1Mb/s). Referenced to external power supply.

Configurable termination resistor with switch.

Other interfaces

Mini USB 2.0

Bluetooth 5.0 Low Energy.

General Input

2x analog / digital (configurable) signal up to 36 Vdc.

4x dry contact digital input.

Configurable to multiple functions (ignition key, HVIL, relay feedback etc.).

General Output

6x independent channels.
External supply voltage. Maximum total output 4 A. External fuse recommended.

Channel 1-4: 2 A nominal, 4 A peak per channel.

Channel 5-6: 1 A nominal, 2 A peak per channel.

Adjustable PWM @ 10 kHz max.

Open circuit, short-to-battery and short-to-ground detection.


Integrated redundant EEPROM to store system configuration and maximeter.

MicroSD support (up to 16 GB). MicroSDHC Class 10 is recommended.

Operating temperature range-40 to +85 ºC

Up to 16 devices in parallel without external hardware.

Dimensions80 x 70 mm

Cell measurements

(voltage & temperature)

Multiple cell chemistry and supercapacitors.

Extended internal redundancy and hardware integrity diagnostics.

Open wire detection.

Cell voltage

5 – 12 cells. 0 – 5 Vdc.

± 1,5 mV cell voltage max total error.

Cell temperature

Up to 3 channels. Configurable NTC.

± 1 ºC cell temperature max total error.

BalancingAutonomous. Configurable. Up to 300 mA per channel.
Operating temperature range-40 to +85 ºC
Dimensions54 x 92 mm

All wBMS models are compatible with the same wBMS-Toolkit, a free PC software that provides real-time monitoring of all BMS measurements, as well as configuration of thousands of parameters in a flexible and intuitive way.

Connection between wBMS-Toolkit and the devices can be established through USB, CAN bus, Ethernet or even Bluetooth.