Chapter 01 · Climate & transitionEnergy & Transition
Battery management system (BMS)
Definition
An electronic system built into or added to rechargeable battery packs that performs three core functions: monitoring (voltage, current, temperature, state of charge and state of health), protection (against overcharge, over-discharge, short circuits and temperature extremes that could trigger thermal runaway), and optimisation (cell balancing and charge control to maximise capacity and lifespan).
References
Supports definition and framing.
Supports definition and framing.
Overview
What it means
Lithium-ion batteries carry a flammable electrolyte and are damaged by operation outside narrow limits; the BMS is the safety and durability layer that makes them usable in vehicles and grid storage. It calculates how much current can safely flow, balances cells (actively or passively), and shuts the battery down when thresholds are crossed — which is why lithium systems cut off rather than fade.
How it is used
Every EV and stationary battery system incorporates a BMS; its data (state of health, cycle history) increasingly feeds battery passports, second-life assessment and warranty management — linking it to circular-economy and traceability requirements such as the EU Battery Regulation.
Why it matters
Battery safety, lifespan and residual-value assessment all depend on the BMS: better management extends first life, enables second life and reduces fire risk — material factors in the sustainability of electrification at scale.