Overview
ISO 20574:2019 - Road vehicles - Durability test method for starter motor for stop and start system defines requirements and recommendations for durability testing of 12 V starter motors used in stop‑start systems for internal combustion engines. The standard specifies test methods, detailed test procedures, and the capabilities and minimum requirements for test benches so manufacturers and test laboratories can evaluate starter motor endurance under high‑cycle start conditions typical of stop‑start operation.
Key topics and technical requirements
- Test scope and planning
- Defines test types using an actual engine or an engine simulator, and options to control tests via engine ECU or bench controller.
- Requires a test planning matrix to set target cycle counts, sequences (manual, automatic, change‑of‑mind events), temperature targets and pass/stop criteria.
- Test bench capabilities
- Minimum structural and measurement requirements, channel lists and control functionality for repeatable durability testing.
- Annexes A–C describe test bench structures (Type 1–4) for different setups.
- Test procedures
- Stepwise phases: installation/setup, pre‑check, test execution, post‑processing and reporting.
- Emphasis on reproducible recording of starter motor voltage (U_STR), current (I_STR), cranking time, overrunning time and temperature.
- Supplemental methods
- Brush temperature calibration, brush length measurement and starter motor input V–I curve verification to ensure thermal/mechanical stress is representative.
- Measurement of pinion to ring gear axial gap and other mechanical checks relevant to wear.
- Reporting and acceptance
- Documented reporting items and defined test stop criteria to determine pass/fail and enable consistent communication between suppliers and OEMs.
Practical applications and who uses it
- Starter motor manufacturers - for R&D, product validation and determining design margins for stop‑start duty cycles.
- Vehicle and engine manufacturers (OEMs) - to specify and verify supplier components and ensure system‑level durability under stop‑start usage.
- Independent test laboratories - to provide standardized, repeatable durability test reports for purchasing and engineering teams.
- Quality and supplier engineering - to set acceptance criteria, perform batch testing and support warranty investigations.
Related standards
- ISO 8856 (referenced normative standard) - electrical performance and test methods for starter motors; used alongside ISO 20574:2019 to cover electrical measurement and general requirements.
Keywords: ISO 20574:2019, starter motor durability test, stop‑start system, test bench, engine simulator, V–I curve, brush temperature, cranking, overrunning, starter motor manufacturer, vehicle manufacturer.
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