Battery Monitoring System for Commercial Trucks


Battery Monitoring System for Commercial Trucks

BMS-300 Battery Monitoring System is designed specifically for commercial truck and fleet applications.  It is installed in the truck permanently to measure battery capacity to help drivers and fleet managers avoid dead batteries in real time.

  • Measures voltage, current, and temperature up to 1,000 times per second
  • Provides CCA measurement of the system every time the vehicle starts, just like a tester
  • Calculates battery state of charge and state of health
  • Measures and reports lowest voltage and highest current during start events. Measures and reports current up to 3,000 amps to help users understand why voltage may be dropping or why vehicle is difficult to start
  • All data reported through CAN J1939 messages
  • Trending BMS values through telematics can help warn of potential no-start scenarios
  • Sleep mode saves energy when truck is not in use


  • Low resistance, heavy duty shunt is suitable for starting circuits
  • Sealed to IP6K9K rating for in-vehicle use
  • Heavy duty truck rated sealed connector on a wiring harness makes connection easy and durable
  • Electronic components sealed in plastic
  • Chemical resistant construction

Battery Management Processes

Midtronics products are designed to meet a variety of battery and electrical system service requirements, but selected features on individual products may make them a better fit for your unique service applications. This product is particularly well-suited for these battery management processes:

Condition-based management icon

Condition-Based Management

Service diagnostics icon

Service Diagnostics

Preventative maintenance icon

Preventative Maintenance

Avoid No-Starts by monitoring battery, starter, and alternator data in real time

Increase time between service intervals. If BMS indicates strong batteries and low resistance, then no service is needed.

Analytics and Communication

  • Send BMS-300 CAN Messages to Fleet Managers Via Telematics
    • BMS-300 provides early warning of electrical problems
    • CAN data from BMS sent through telematics
    • Telematics feeds data to maintenance and tracking systems in real time
    • Notifies fleet manager of issues
Diagram of Midtronics BMS-300 sending messages to BMIS dashboard on fleet battery performance


  • Group 31


  • 12-volt battery packs up to 8 batteries
    • Flooded Lead-Acid
    • AGM Spiral & Gel
    • Enhanced Flooded (EFB)
    • NorthStar and Odyssey Pure Lead


  • Voltage
  • Current
  • Temperature
  • State of Charge
  • State of Health
  • Conductance (CCA)
  • Starting Voltage
  • Inrush Current
  • Amp-Hour Counter


  • Shunt is mounted to chassis ground battery post
  • Positive battery
  • CAN High
  • CAN Low
  • CAN ground
  • Relay (Optional)
  • Secondary battery positive (Optional)
  • Secondary battery negative (Optional)
  • Ignition (Optional)


  • Wired Communication via Cable and Connector
  • CAN J1939 messages
  • Different battery quantities and types flashed via EEPROM


  • Powered via shunt and cable connections
  • Mounts to Group 31 chassis ground battery terminal
  • Sleep mode reduces power consumption.

WARNING: Cancer and Reproductive Harm -

Midtronics works closely with individual customers to develop custom BMS-300 solutions. Please contact your Midtronics account manager for more information.