Why MGN-681 Chapter 4 Should Not Be Viewed as a box-ticking exercise Why MGN-681 Chapter 4 Should Not Be Viewed as a box-ticking exercise

“We need a type approval. But why is that so important?” “Do you have a type approval? But for what exactly?” These are typical questions we’ve been asked during the more than 200 surveys we’ve completed in recent years.

These are valid questions, especially in the early days when the first yachts caught fire due to lithium batteries. Several companies stepped up, quickly developed storage solutions, and—without any guidance—simply supplied them to quite a few vessels over the past few years. It depended on who we spoke with on board: we encountered situations where captains weren’t interested because they didn’t see the potential issues, but the crew was eager to meet with us; or situations where we met a crew that had recently come on board because their previous vessel had burned down. They just want to make sure it doesn’t happen again.

I’ve written this article to explain what this updated Amendment 1 to the MGN is really about, based on real-world experience on board. All the solutions we provide to the industry are simply the best available. The issue is that some of these solutions are not yet type-approved because they are generations ahead of the updated MGN version. We were involved in the initial review of MGN-681 back in 2021–2022, and some of the updates we recommended at that time have now been incorporated into the update. So the companies developing new technology are years ahead of the legislation.

Lithium-ion systems are rapidly becoming standard equipment on modern vessels, but they present a fundamentally different risk profile that is still not fully understood across the industry. Why is the market only talking about obtaining type approval, when this does not provide any assurance in terms of onboard safety and compliance?

With the introduction of MGN 681 Amendment 1, significant progress has been made. At the same time, we are seeing a growing tendency to equate compliance with safety and to focus on isolated solutions rather than the entire system.

I wrote this article to provide clarity from a practical, real-world perspective. Not just what is required, but what actually works on board. And what can help prevent incidents that people pretend don’t exist. Because when it comes to lithium-ion safety, compliance is only the starting point.

MGN 681 Amendment 1 is an important and welcome development for the yachting industry. It recognizes that lithium-ion-powered tenders, jet skis, water toys, and spare batteries present a fundamentally different risk profile than traditional fuel-powered equipment. The guidance makes clear that safety onboard must address fire prevention, storage, detection, and suppression as a comprehensive system.

However, there is a growing misconception that simply complying with Chapter 4—particularly by using a type-approved storage or charging cabinet—is enough to ensure a safe onboard environment. That is not the case.

To understand this properly, it is important to consider why Chapter 4 has become more prescriptive. From that perspective, the shift toward type approval is both logical and necessary. It introduces accountability, establishes a baseline for safety, and helps owners, captains, and shipyards navigate what has historically been a fragmented market. This is something we fully support. However, there is an important nuance: type approval under Chapter 4 demonstrates compliance with a defined set of criteria, primarily focused on containment, structural integrity, ventilation, and response to failure. It does not automatically ensure the highest level of safety in practice, particularly when it comes to prevention, early detection, or system integration.

The increased focus on defined requirements and Type Approval is, in part, a response to market conditions in recent years. The yachting industry has seen a wide range of storage and charging solutions introduced, not all of which have met acceptable safety standards. Inconsistent engineering approaches, unclear performance claims, and, in some cases, fundamentally unsafe products have led to a need for clearer rules and stronger validation.

This creates a critical gap. A product may be fully compliant and type-approved, yet still be less effective at preventing an incident than a more advanced, prevention-focused solution that may not (yet) fall within that specific approval framework.

At Liiontek, we position ourselves as a specialist advisor, not a product-driven supplier. Our approach is unbiased and focused on real-world safety outcomes. This means we support type-approved solutions when appropriate, but we are equally transparent when a non-type-approved solution may offer a higher level of safety due to earlier detection, stronger prevention mechanisms, or better integration with onboard systems.

Compliance is important, but it should never be confused with the highest possible safety standard.

Chapter 5 introduces type approval for storage and charging solutions, and it represents an important step forward for the industry. We strongly support the introduction of type approval. It brings structure, consistency, and a clearer benchmark for safety to a market that has historically seen wide variations in product quality and performance. Establishing defined testing and approval pathways helps raise the overall standard and provides reassurance to owners, captains, and shipyards.

At the same time, it is important to understand how this requirement is currently enforced. Type approval is not mandatory for all installations until 01-01-2027. This means that many systems already installed on yachts are not subject to these approval requirements. As a result, there is currently a mix of solutions in use, ranging from newer systems that comply with emerging standards to legacy installations developed under earlier practices. This transitional phase is a natural part of the industry’s evolution.

It is also worth noting that MGN 681 remains a guidance document, not a formal legal requirement. It has played a key role in raising awareness of lithium-ion safety and setting the direction for the sector, which is a very positive development. At the same time, like any guidance, it continues to evolve and should be interpreted as part of a broader safety framework rather than as a complete or final solution.

Type approval, therefore, should be viewed as an important component within a broader safety framework, but not the sole measure of safety. True onboard safety is achieved through a combination of compliant products, system integration, early detection, prevention strategies, and proper operational procedures.

If the industry is serious about moving toward prevention and real-world safety, it also needs to reconsider how solutions are evaluated. This is where a system-level test such as UL 9540A (6th edition) becomes highly relevant.

Unlike more traditional approval pathways that may focus on individual components or specific functional requirements (such as containment or ventilation), UL 9540A evaluates how a lithium-ion system behaves under failure conditions: thermal runaway propagation, heat release, gas generation, flame spread, and the effectiveness of mitigation strategies within a complete system.

This aligns much more closely with how lithium-ion incidents actually unfold. This is a much more sophisticated method of testing a storage and charging solution than, for example, UL 1487, a test used for ‘passive’ boxes and containers. These tests are primarily designed to address thermal runaway situations. This still means that with such approved systems, you still have to wait for a fire to start before the box begins to respond.

Thermal runaway is not a single-component issue; it is a system failure. It involves interactions between cells, modules, enclosures, ventilation, detection systems, and suppression measures. Testing that focuses solely on isolated features cannot fully capture this complexity. A system-based test approach reflects:

• How failure begins at the cellular level
• How it spreads through a battery or storage environment
• How Gases Are Generated and Managed
• How Detection and Suppression Systems Work Together
• Whether escalation is prevented or merely contained

In many ways, this approach is closer to the original intent behind MGN 681: treating lithium-ion safety as a holistic onboard system, not as a collection of independent compliance requirements. It also reinforces a key point: true safety is not defined by whether a product passes a test; rather, it is defined by whether the system prevents the situation from escalating in the first place.

As industries evolve, we believe that system-level validation methods such as UL 9540A should play a greater role in decision-making. They provide a more realistic understanding of risk and performance, and they better support a prevention-led safety philosophy.

Another important concern within the industry is not just what is approved, but how Approvals are being granted. We are seeing inconsistencies among vessels operating under the same flag and class. In some cases, one vessel is required to install a type-approved solution or is not permitted to carry such equipment at all. In other cases, vessels subject to the same regulatory framework have been allowed to use standard lockers or non-specialized spaces as “approved” lithium-ion storage.

This inconsistency raises serious concerns. Lithium-ion battery risks are complex, rapidly evolving, and still relatively new to the maritime sector. Determining what constitutes a safe solution requires specialized knowledge of battery failure modes, thermal runaway behavior, gas generation, and system integration. This is not an area where subjective interpretation or case-by-case judgment should play a dominant role without a clear technical basis.

When approval decisions vary significantly depending on the individual assessor, surveyor, or interpretation of guidelines, it creates uncertainty across the industry and, more importantly, leads to inconsistent levels of safety on board. In our view, there should be a more consistent and technically robust approval process. Clear standards, applied uniformly, are essential. The current situation, in which similar vessels receive different approvals for fundamentally different levels of protection, is not commensurate with the level of risk posed by lithium-ion technology.

Chapter 4 plays an important role, but by design it is largely reactive. It focuses on storage and charging arrangements, fire-rated boundaries, ventilation, shutdown systems, and the management of off-gases. These are all essential elements, but they are primarily intended to respond to an incident once it has already begun to develop.

Ventilation requirements are designed to keep gas concentrations below explosive limits once outgassing has begun. Fire suppression measures are designed to control or extinguish a fire that has already started.

This is not prevention. This is containment and damage control.

That distinction is critical because lithium-ion incidents escalate rapidly. Once thermal runaway begins, it becomes extremely difficult to control. Batteries can continue to generate heat without external oxygen, reignite after being suppressed, and produce toxic and flammable gases. A system that only reacts at this stage is already responding too late in the failure curve.

To truly understand onboard safety, the focus must shift to the earlier stages of intervention and system design. Chapter 6 is fundamental because it introduces monitoring and intervention before a failure escalates. A BMS can track current, voltage, individual cell behavior, and temperature, and initiate countermeasures such as isolating faults or disconnecting the battery. MGN 681 recommends integration with the vessel’s alarm and monitoring systems. This is the foundation of prevention.

It builds on this by emphasizing early detection. Smoke, heat, and gas detection, CCTV monitoring, remote alarms, and even thermal imaging all play a role in providing visibility before a situation becomes critical. The mention of off-gas detection—even as a developing technology—is particularly important, as it signals a shift toward identifying failures at their earliest stages.

It highlights the complexity of lithium-ion incidents. Water-based systems, water mist, portable extinguishers, fire blankets, and containment solutions are all required because no single method is sufficient. The explicit warning about re-ignition reinforces the fact that suppression is not a one-step solution, but part of a layered safety strategy.

It is the final and often underestimated element. The crew must be able to identify damaged batteries, recognize warning signs, and respond appropriately. Without this, even the best technical systems can fail in practice.

Together, these chapters outline a safety philosophy that goes far beyond storage. They outline a system.

This is also where the current guidance still has room for improvement. MGN 681 acknowledges early detection technologies, but it does not strongly encourage the industry to adopt prevention-first solutions. As a result, many products on the market are still designed to respond to heat, smoke, or fire rather than to intervene before thermal runaway occurs.

Solutions such as the Schneider Containment Generation 4 (SC-4 platform) represent a different approach. These systems are described as being engineered to prevent thermal runaway before it begins, using ultra-sensitive single-cell detection, active ventilation, filtration, automated countermeasures, and integrated alarm systems. This shifts the role of the cabinet from passive containment to active prevention.

That difference is fundamental. A Type Approval based solely on Chapter 4 demonstrates compliance with containment and response requirements. It does not demonstrate that a system provides the earliest possible detection or the strongest prevention capability. As such, it should be viewed as a baseline, not a benchmark for the highest level of safety.

Even the most advanced system can be compromised if it is not installed and integrated correctly. MGN 681 treats lithium-ion safety as a vessel-wide system that involves ventilation, alarm integration, firefighting arrangements, and control systems. Products such as the SC-4 platform are also designed with integration in mind.

If these systems are installed improperly, ventilated incorrectly, or not properly connected to the onboard monitoring and alarm infrastructure, their effectiveness can be significantly reduced. Early warnings may not reach the intended location, suppression systems may not function as intended, and ventilation may not perform as expected under actual conditions.

In practice, poor installation can compromise even the highest-quality product.

MGN 681 Amendment 1 should not be interpreted as a checklist that ends with Chapter 4. Chapter 4 is important, but it is only one part of the safety equation. True onboard safety comes from combining prevention (Chapter 6), early detection (Chapter 7), effective suppression (Chapter 8), and a trained human response (Chapter 9), all supported by proper installation and system integration.

The industry should be careful not to confuse “Type Approved” with “Safest Possible Solution.” When it comes to lithium-ion risks on board vessels, the goal is not simply to contain a failure; it is to prevent it.

Liiontek stands ready—not as a follower of regulations, but as a leader in prevention. Because heroes don’t wait for disaster. They engineer a future where disaster never gets the chance.