Overview
ISO 23625:2025 - Small craft - Lithium-ion batteries - specifies requirements and recommendations for selecting, installing and documenting lithium‑ion batteries on small craft. It applies to lithium‑ion batteries and battery systems with a capacity greater than 500 Wh used for general electrical loads and/or electric propulsion. The standard is primarily intended for manufacturers and battery installers and replaces ISO/TS 23625:2021 with expanded guidance on BMS, EMC and protection devices.
Key technical topics and requirements
- Scope and applicability: Batteries > 500 Wh; warning that DC systems operating at potentials ≥ 60 V have additional requirements not covered by this document.
- System design: Installations must follow ISO 13297 and the battery manufacturer’s recommendations; systems must keep batteries within the manufacturer’s safe operating limits (SOL).
- Battery Management System (BMS): A BMS is required to protect against overcharge, overdischarge, high/low temperature events (HVC/LVC/HTC/LTC) and to provide battery cut‑off under hazardous conditions. EMC requirements for BMS are included.
- Standards compliance: Batteries shall meet IEC 62619 and IEC 62620 requirements.
- Alarms and operator notification: For propulsion or critical systems, the BMS must notify the operator with a visual and/or audible alarm (75–85 dB(A) at 1 m) before disconnecting the battery.
- Installation practices: Protection from shock, vibration, corrosion and heat; adhere to specified temperature limits and storage guidance; no series connection of different chemistries; provide overcurrent protection and appropriately rated contactors/disconnect devices.
- Ingress protection: Components in flood‑prone locations must meet IP67; others should meet IP55 (IEC 60529).
- Higher‑level requirements: For propulsion installations > 1 500 Wh, the system shall be capable of indicating state of health relative to original capacity.
- Safety information: Manufacturers must supply required safety information and an operator’s manual.
Informative annexes cover battery thermal runaway, protection devices, and protection device examples.
Practical applications and users
- Who uses ISO 23625:2025:
- Marine battery manufacturers and OEMs
- Small craft designers and boatbuilders
- Marine electrical installers and service technicians
- System integrators of electric propulsion and hybrid drives
- Surveyors and certification bodies assessing battery installations
- Practical uses:
- Specification and selection of marine lithium‑ion battery systems
- Installation checklists and commissioning procedures
- BMS configuration, alarm strategy and safety documentation
- Risk mitigation for thermal runaway, corrosion and water ingress
Related standards
Keywords: ISO 23625:2025, small craft, lithium‑ion batteries, marine batteries, battery management system, BMS, safe operating limits, battery installation, battery safety, electric propulsion.
