Reference design for battery management system for Lead acid Batteries




Almost 80% of the vehicles presently used runs on Lead-acid batteries either as primary power source or for accessories.

The reference design deals with the development of smart BMS for Lead-acid batteries.


battery management system (BMS) is an electronic system that manages a rechargeable battery (cell or battery pack), such as by protecting the battery from operating outside its safe operating area, monitoring its state, calculating secondary data, reporting that data, controlling its environment, authenticating it and / or balancing it. A battery pack built together with a battery management system with an external communication data bus is a smart battery pack. A smart battery pack must be charged by a smart battery charger.

The design is based on the Battery Management System Developed by NXP semiconductors. The RD9Z1-638-12V-C reference design is a Battery Management System (BMS)for 12 V lead-acid battery applications and features the MM9Z1J638 Battery Sensor

While designing a BMS, the key parameters should be taken in concern are –

  • The microcontroller used to design the algorithm. The controller used should be having low power consumption and multiple communication ports to create an efficient system.
  • The design should include current and Voltage sensing options as cutoff voltages are very important in battery charging. This helps in maintaining the nominal voltages of the battery cells.
  • Industrial Communication Supports like JTAG and CAN to integrate it with present infotainment systems.
  • Battery temperature Measurement Modules to optimise the power loss during charging of the batteries.

While these are the essential parameters of BMS design, New chargers support multiple types of battery charging like Lithium-ion, Lead-acid, and Lithium Polymer batteries. These parameters should be altered according to the battery to be charged.

Some of the features provided in the reference design are –

  • It supports S12z microcontroller which is an industrial-grade microcontroller.
  • It comes with a reverse polarity circuit to provided safety to the input operable circuit.
  • It is equipped with Battery Voltage Sensing Input and Battery Input Charge Current sensing.
  • It is integrated with an onboard temperature sensing module for monitoring the temperature of battery while charging.
  • It is programmable and can be debugged using a BDM interface.
  • It supports the Controller Area Network (CAN) protocol which helps in decreasing point to point wiring systems.
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The reference design includes all the necessary documentation including schematics, Circuit diagram, BOM etc. All the necessary documents can be downloaded here.

Note: You need a Valid NXP account in order to download the design documents.



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