Battery management system

Example

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Use in Lemonergy

Make series/parallel architecture explicit.

This is a reference concept. No executable Lemonergy block has been verified for this term.

Learn it in Lesson 0 · Battery basics →

Connected concepts

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CAN bus

The serial network over which a BMS talks to the vehicle or inverter: a two-wire differential bus, defined in ISO 11898, carrying short prioritised messages at up to 1 Mbit/s, or faster with CAN FD. Every node hears every message, and a dominant bit wins arbitration without any collision.

Cell balancing

Equalising the state of charge of cells in series, since the pack is limited by its emptiest cell on discharge and its fullest on charge. Passive balancing bleeds charge from high cells through resistors; active balancing moves it between cells.

Cell supervision circuit

The board on each module that measures its cell voltages and temperatures and switches its balancing resistors, reporting to the central BMS controller. It is usually built around a dedicated monitoring chip and linked by isoSPI or CAN.

Contactor

A heavy-duty electrically operated switch that connects the pack to the vehicle or inverter and opens it on fault or shutdown. Packs use at least two, one per pole, plus a pre-charge path to avoid welding them on the first connection.

State of charge

How full a cell is, as a fraction of its available capacity. State of charge, like temperature, affects how fast a stored cell ages.

State of power

The maximum charge or discharge power a battery can deliver for the next few seconds without breaking a voltage, current or temperature limit. The BMS recomputes it continuously from SOC, temperature and resistance and sends it to the motor controller.

References & further reading

Technical references

1. Getting Started with the BQ76925

   Texas Instruments · 2019

   Technical reference · A concrete BMS analog front-end example: cell voltage, current, temperature measurement and MCU integration.

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

2. Extended Kalman filtering for battery management systems of LiPB-based HEV battery packs: Part 2. Modeling and identification

   Gregory L. Plett · Journal of Power Sources · 2004

   Topic background · Battery charge balance, open-circuit voltage, ohmic loss, polarization dynamics and model identification; parameters require cell-specific data.