Operational guide · Safety & equipment

Fire Safety of Onboard Battery Rooms (BESS)

BESS response follows the approved emergency plan and installed design: alarm, segregation only as designed, ventilation control and approved fixed suppression/cooling from a safe position; no entry until explosion/toxic risk is assessed and authorised.

BESSbattery roomthermal runawayhybrid electric

Operational Explanation

Regulatory Reference

Approved flag/class design and SMS; EMSA BESS Guidance is non-mandatory; SOLAS II-2/17 only where it is the actual alternative-design route.

For lithium-ion batteries, thermal runaway can release toxic and flammable gases and spread to other cells. Absence of flames does not establish that the event has stopped: maintain the prescribed monitoring and measures against re-ignition, gas accumulation and damage to adjacent compartments. EMSA BESS Guidance, fire and explosion hazards.

Ventilation and extinguishment must follow a coordinated strategy: gas extraction and inerting agents may require different arrangements. Do not transfer a generic ventilation shutdown sequence to the BESS room; use the approved plan’s controls and sequence and keep hazardous areas near exhaust outlets clear. EMSA BESS Guidance, ventilation and extinguishment.

Scope of Application

Training, familiarisation and drills to the extent required by approved design, risk assessment, flag/class and SMS; not automatically every drill for every hybrid ship.

Procedure / How to Complete It

From a safe position raise alarm and identify the event.
Stop/segregate only as designed.
Control ventilation and activate the approved fixed strategy.
Do not generically apply water or electrical isolation.
Prohibit entry until explosion/toxic-atmosphere risk is assessed and entry authorised.
Integrate hazards into training/drills under the approved regime.

Practical Example

The plan may use water-based, inerting or combined means: the team uses the installed system and does not enter merely because visible flame has ceased.

What Typically Goes Wrong

Imposing massive and prolonged cooling, improvising isolation/water, entering before risk clearance, or treating EMSA/drills as universally mandatory.

Common Mistakes Mistake Library

Mistake	Consequence	How to Avoid It
Imposing massive and prolonged cooling, improvising isolation/water, entering before risk clearance, or treating EMSA/drills as universally mandatory.	Non-compliant decision or treatment	Follow the approved arrangement and applicable sources

What the PSCO Checks

Check the BESS plan, availability of detection, ventilation, protections and remote controls; maintenance, defects and crew competence. Personnel should know entry restrictions, gas-exposed areas and post-event monitoring measures.

Operational Tips

Separate current requirement, class/maker, SMS and voluntary guidance.
Do not improvise tests, thresholds or intervals.
Record deviations and corrective action.

Preparation checklist

Approved response plan
Remote safe controls
Ventilation/suppression design
Explosion/toxic entry gate
Approved training scope
EMSA non-mandatory

FAQ

Is water always the response?

No. Follow the approved design and strategy.

When may personnel enter?

Only under the approved plan, after assessing explosion, toxic atmosphere, re-ignition and residual electrical-energy risks, with authorisation and prescribed protection. Absence of flames is not a sufficient criterion.

Is EMSA mandatory?

It is non-mandatory guidance; requirements follow the applicable arrangement.

Fire Safety of Onboard Battery Rooms (BESS)

Operational Explanation

Regulatory Reference

Scope of Application

Procedure / How to Complete It

Practical Example

What Typically Goes Wrong

Common Mistakes Mistake Library

What the PSCO Checks

Operational Tips

Preparation checklist

FAQ

Related Topics