ISO 12405-4 - Battery Design

Test Specification for Lithium-Ion Traction Battery Packs and Systems for Electrically Propelled Road Vehicles (Performance Testing)

ISO 12405-4 is an international standard published by the International Organization for Standardization (ISO) that specifies standardised test procedures for the performance, reliability, and electrical functionality of lithium-ion traction battery packs and systems used in electrically propelled road vehicles. It is the performance testing part of the ISO 12405 series and applies to both high-power battery systems (typical of hybrid electric vehicles) and high-energy battery systems (typical of battery electric vehicles and plug-in hybrids). Cell-level performance testing for Li-ion traction cells is addressed in the IEC 62660 series.

Published by: International Organization for Standardization (ISO)

Current edition: ISO 12405-4:2018 (published July 2018)

Series context: Part 4 supersedes and consolidates Parts 1 (high-power HEV, 2011) and Part 2 (high-energy BEV, 2012) of the ISO 12405 series for performance testing; ISO 12405-3:2014 covers safety testing

Primary applications: HEV, PHEV, BEV, FCV road vehicles

Scope

ISO 12405-4 applies to lithium-ion traction battery packs and systems for electrically propelled road vehicles. Unless otherwise stated, test procedures apply to both application types:

High-power applications: hybrid electric vehicles (HEVs) and fuel cell vehicles (FCVs) where the battery provides power assist and regenerative braking; smaller battery capacity but high peak power capability
High-energy applications: battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and FCVs where the battery is the primary energy source; larger capacity optimised for range

Exclusions: Cell-level testing is not within scope (covered by IEC 62660-1 and IEC 62660-2). Safety testing at pack/system level is addressed separately in ISO 12405-3. The standard does not cover light electric vehicles (L-category) for which ECE R136 and EN 50604-1 apply.

Key Test Procedures

Capacity and Energy Tests

Rated capacity: constant current (C/3 or C/5) full charge/discharge cycle at 25 °C; measured delivered capacity must meet manufacturer specification
Energy measurement: total energy delivered during constant-current discharge from full state of charge (SoC) to minimum cut-off voltage
Capacity at temperature extremes: discharge tests at −10 °C and +45 °C to characterise available energy across the operating temperature window

Power Tests

Pulse power characterisation (PPC): a key test in ISO 12405-4; applies defined current pulses (charge and discharge) across the SoC range to map peak power capability at multiple SoC and temperature points
Continuous power: maximum sustainable discharge power at defined SoC and temperature points
Peak power (cold start): power capability after conditioning at −10 °C or −18 °C to simulate cold weather starting conditions

Efficiency and Self-Discharge

Charge/discharge efficiency: ratio of energy returned on discharge to energy input on charge under defined conditions
Self-discharge: open-circuit voltage and capacity loss after defined storage period (typically 30 days) at elevated temperature (40 °C or 45 °C)

Reliability and Cycle Life

Cycle life under defined protocol: repeated charge/discharge cycles using application-representative current profiles; capacity must remain above 80% of initial rated capacity for the manufacturer-declared cycle count
Calendar life assessment: not directly specified but linked to capacity measurements over defined storage intervals

Functional Tests

SoC estimation accuracy: comparison of BMS-reported SoC to measured values across the operating range
Voltage imbalance: maximum cell voltage spread within the pack monitored throughout tests
Thermal behaviour: surface temperature monitored and recorded during high-rate tests

Regional Adoption and Related Standards

Europe: ISO 12405-4 is widely referenced in EV type-approval and OEM procurement specifications across the EU and UK
China: GB/T 31486 and GB/T 31467 cover similar territory; ISO 12405-4 is referenced in international OEM programmes
USA: SAE J1798 covers similar performance test methodology; ISO 12405-4 is used for international market programmes

Related Standards

IEC 62660-1 — Performance testing of Li-ion cells for EV propulsion (cell-level; ISO 12405-4 addresses pack/system level)
IEC 62660-2 — Reliability and abuse testing for EV Li-ion cells
IEC 62619 — Safety requirements for industrial Li cells and batteries; relevant for stationary storage rather than traction
BS EN 50604-1 — Safety requirements for light EV traction batteries (L-category vehicles); ISO 12405-4 addresses M and N category road vehicles
ISO 12405-3:2014 — Test specification for lithium-ion traction battery packs and systems — Part 3: Safety performance requirements (the safety testing counterpart to Part 4)
SAE J1798 — Recommended practice for performance rating of electric vehicle battery modules (US equivalent performance standard)

Disclaimer: This is not a definitive guide, just an indication and it is important that you always go back to the source for legislation.