IEC 62619 vs. UL 1973: Understanding Industrial Battery Standards

Introduction

Because a single battery fire can halt a promising hardware startup, choosing the right energy storage safety standards to design your product around is of utmost importance.  Founders are betting with their wallets too, as the global battery testing and certification market is projected to soar from $9.3 billion in 2024 to $55.4 billion by 2033 .

With investors, insurers, and regulators watching closely, founders must decide early whether IEC 62619 or UL 1973 applies to their energy-storage product. This guide unpacks each standard, compares their technical demands, and offers a framework for selecting (or combining) them. The core message: treat compliance as a strategic enabler, not a last-minute checkbox.

Key Points

• IEC 62619 targets cell-level safety by proving lithium-ion cells and small batteries won’t ignite, while UL 1973 focuses on module/rack containment and Battery Management System (BMS) functionality. Most North-American stationary systems need UL 1973, and global products often need both.
• Choose standards by chemistry, voltage, installation locale, and customer/insurer demands; stationary U.S. Energy Storage System (ESS) units (>60 V) usually mandate UL 1973, whereas international or mobile industrial gear leans on IEC 62619.
• Plan for dual certification early: design to the stricter clause, align firmware limits, and create a unified safety file to cut retest costs and shave months off market entry.
• Early compliance can help secure financing and insurance, while reducing retest risks
• IEC 62619 and UL 1973 reports feed into broader requirements like UL 9540/9540A (fire safety hazards) and NFPA 855 (installation of stationary energy storage systems), so passing them streamlines subsequent grid-code and fire-code approvals.

Why Battery Safety Standards Matter for Emerging Energy Storage Products

Battery safety standards create a common language of trust. Whether mandatory (codified by law) or voluntary (referenced by customers and insurers), they:

• Prevent catastrophic failures by stress-testing cells, modules, and racks against electrical, mechanical, and thermal abuse. Lithium-ion failure rates, in EV vehicles for instance, are as low as 0.03% per vehicle per year, but high-profile incidents still make headlines.
• Unlock financing and insurance. Standardized, demonstrable safety processes for battery energy storage directly accelerate adoption and investment in new ESS projects
• Accelerate market adoption. Intrinsic safety not only builds confidence with insurers and regulators, it also speeds up commercialization. As Enerpoly CEO Eloisa de Castro explains: “This intrinsic safety allows us to move faster, scale responsibly, and earn the trust of partners without compromise”.

IEC 62619 Explained: Scope, Testing Regime, and Use Cases

IEC 62619 is an international standard developed by the International Electrotechnical Commission (IEC) for “secondary lithium cells and batteries for industrial applications.”

• Scope: Covers complete batteries and individual cells intended for stationary energy storage, motive power (e.g., forklifts), and industrial equipment.
• Chemistries: Any lithium-based system (LFP, NMC, NCA, etc.) as long as electrolyte is non-aqueous.
• Key test groups
  
  • Electrical abuse: overcharge, over-discharge, and external short-circuit.
  • Thermal abuse: thermal stability and forced thermal runaway.
  • Mechanical abuse: vibration, drop, and shock.
  • Environmental: altitude, temperature cycling, and humidity.
• Sample sizes: Typically five to eight cells or battery units per test, emphasizing statistical confidence.
• Pass/fail criteria: No explosion, no fire, casing integrity maintained, and voltage/temperature within limits.

Typical applications include grid-scale battery containers, UPS (uninterruptible power supplies), and industrial mobile robots—especially for companies shipping products into multiple regions that recognize IEC standards.

UL 1973 Explained: Scope, Testing Regime, and Use Cases

UL 1973 is a North American safety standard titled “Batteries for Use in Stationary, Vehicle Auxiliary, and Light Electric Rail Applications.”

• Scope: Evaluates battery modules, packs, and racks—not individual cells—used in stationary energy storage systems (ESS), telecom backup, and light-rail support.
• Component focus: Requires verified Battery Management System (BMS) interfaces, protective housings, and deflagration (explosion-relief) mechanisms.
• Signature tests
  
  • Thermal runaway propagation using calorimeters or UL 9540A methodology to confirm event containment.
  • Deflagration panel effectiveness to vent flammable gases safely.
  • Electrical isolation and ground-fault detection.
  • Functional safety of disconnect devices triggered by BMS.
• North American adoption: Frequently required by U.S. states with high renewable penetration, such as California, Hawaii, and New York, since they usually require NFPA 855 and UL standards (including UL 1973).

Because UL 1973 tests larger assemblies and their controls, it is often paired with cell-level standards (such as IEC 62619) to create a holistic safety case.

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IEC 62619 vs. UL 1973: Key Technical Differences

Sources: Twaice, TUV SUD.‍

Key takeaway: geography alone does not dictate the choice. UL 1973’s methodology assumes that a failure will occur and focuses on containment, while IEC 62619 aims to prevent cell-level ignition. Mature products often need both perspectives.

Mapping Applicability: Which Standard Governs Your Battery System?

Use the following decision points to map battery standard applicability:

• Chemistry: Lithium-ion? Both standards apply. Zinc-ion or lead-acid? Neither IEC 62619 nor UL 1973 fits; look to IEC 62902 or UL 1989.
• Voltage class: Above 60 V DC generally triggers UL 1973 module testing in the U.S.
• Installation context: Stationary ESS containers fall under UL 1973/NFPA 855. Mobile industrial equipment shipped worldwide benefits from IEC 62619.
• Market geography: Selling only to U.S. utilities? Prioritize UL 1973. Planning EU pilots? IEC 62619 may be required by insurers.
• Customer procurement specs: Large EPC (engineering, procurement, construction) firms often demand proof of both standards to streamline global deployment.

When edge cases arise—such as a U.S. microgrid destined for overseas expansion—plan for dual certification from day one.

Ensuring Safe Integration from Cell to Container

Compliance is more than passing lab tests; it is about systems thinking:

• Cell selection: Favor chemistries with inherently lower thermal runaway risk (e.g., LFP) to ease abuse testing burden.
• Module partitioning: Fire-resistant barriers between modules limit propagation—a clear UL 1973 expectation.
• Incident containment: Incorporate intumescent (expanding) materials that seal gaps during high heat.
• Deflagration panels:  A mitigation measure recommended by DNV GL when high concentrations of explosive gases are detected. Such measures address risks highlighted by the 2019 McMicken incident, where undetected gas buildup led to a catastrophic blast.
• Emergency stop functions: Design a hardware-level disconnect that BMS can trigger within milliseconds.

Gletscher Energy analysts note that “skimping on BMS integration often becomes apparent only after failures occur,” underscoring why planning your test plan thoughtfully is important.

Designing for Dual Certification: Leveraging Overlapping Requirements

A dual certification strategy of both UL 1973 and IEC 62619 minimizes duplicative testing:

• Design to the stricter clause. If UL 1973 requires 20 mm creepage distance but IEC 62619 asks for 10 mm, adopt 20 mm universally.
• Align diagnostic thresholds. Use one set of state-of-charge (SOC) and temperature limits across firmware to satisfy both reports.
• Modularize safety functions. A standalone DC disconnect unit tested once can serve in both certifications.
• Document in a unified safety file. A single hazard analysis referenced by both certifiers avoids conflicting interpretations.

Startups that integrate dual certification efforts early during prototype development can streamline compliance activities, reduce redundant testing and documentation, and potentially accelerate overall certification timelines compared to sequential approaches.

Strategic Benefits of Early Compliance Planning

Embedding standards early pays off:

• Cost avoidance.  A full retest of a large battery rack, such as a 500 kWh lithium-ion system, can incur laboratory fees exceeding $100,000, and the associated schedule delays can significantly impact project timelines.
• Faster market entry.  Hardware teams that lock standards at the alpha stage reduce approval delays, enabling faster pilot deployments and earlier revenue realization.
• Investor confidence.  Startups that seek certification help signal safety and prudence to investors while developing innovative technology, as was the case for Ambri, a US technology startup commercializing energy storage systems based on a high temperature liquid metal battery.

Early planning reframes compliance from sunk cost to competitive moat.

Navigating the Regulatory Ecosystem: Interactions with NFPA 855, UL 9540, and Grid Codes

Battery standards rarely act alone:

• UL 9540 validates the entire Energy Storage System (ESS) by integrating battery, inverter, and enclosure. Passing UL 1973 supplies the battery portion of that puzzle.
• UL 9540A is a test method—not a certification—that quantifies thermal runaway propagation. Many AHJs request its data even when UL 1973 is achieved.
• NFPA 855 fire code references UL 9540 and UL 1973 for stationary ESS installations, dictating setback distances and ventilation.
• Grid codes such as IEEE 1547 (inverter interconnection) pull component safety data from IEC 62619 to verify ride-through capabilities.
• Environmental touchpoints: Europe’s Battery Regulation and U.S. EPA hazardous waste rules increasingly require traceable safety data, reinforcing the value of formal certification.

The lesson: IEC 62619 and UL 1973 reports cascade downstream, reducing duplicative testing across the regulatory ecosystem.

Conclusion

Choosing between IEC 62619 and UL 1973 is less about geography and more about risk philosophy. IEC 62619 focuses on preventing cell ignition; UL 1973 assumes a failure and demands system-level containment. Forward-looking startups treat these standards as design inputs, not post-prototype hurdles—leveraging overlaps to pursue dual certification when market expansion demands it. By integrating compliance early, teams bolster investor confidence, accelerate deployment, and transform safety into a strategic advantage.