Acculon Energy

Safety: From Start to Scale – Evolving Safety Standards: Highlights of the 2023 UL 2271 Updates for LEVs

Today we’re covering a lot of ground in our discussion about the release of the 3rd edition of UL 2271. Come along as we summarize the most significant changes & consider the implications for stakeholders in the LEV space!

Contact: Betsy Barry
Communication Manager

If you keep up with battery technology and electrification, in the past year there is no doubt you have heard reports in media outlets of the fires associated with products like e-bikes and e-scooters, both of which fall under the category of light electric vehicles or LEVs. Fires, explosions, and general public safety concerns have prompted local governments and municipalities to enact legislation in an attempt to regulate these products to reduce safety risks.

A hearing by the Consumer Product Safety Commission in the summer of 2023 convened to tackle the safety issues surrounding micromobility products that employ lithium-ion batteries. This hearing focused specifically on the micromobility sector, prompting regulatory agencies to revisit prevailing industry standards surrounding LEVs. The result, in part, is an update to UL standards governing these products, namely UL 2271. While these updates may have been a response to safety concerns in the micromobility space, the resulting changes will impact a range of industrial and commercial applications as well.

What is UL 2271?

UL 2271 is a standard that outlines requirements for the safety and performance of electrical energy storage assemblies (EESAs). This safety standard covers light electric vehicles (LEVs), like e-bikes, e-scooters, golf cars, ATVs, lawnmowers, and like-applications that fall under the LEV umbrella. The UL 2271 certification standard evaluates the entire battery system, from its components to its overall architecture. For example, there are rigorous tests that evaluate the battery enclosure’s resistance to environmental factors like impact, heat, flame, and water. Other tests and evaluations ensure the battery’s wiring is properly designed to withstand strain and unintentional shorting through a series of electrical tests. Finally, there are multiple mechanical tests to check the battery’s physical endurance during intense vibration, and being shocked, dropped, and crushed.

UL 2271 was introduced in 2013 and underwent its first significant set of revisions in 2018. These current changes are, in part, a response to increasing concerns about the safety of lithium-ion cells used in e-bikes and e-scooters, both of which fall under 2271, as regulatory bodies try to keep up with the evolving landscape of battery technology and electrification, as well as the safety concerns therein.

What are the significant changes in the 2023 3rd edition?

There are several consequential updates to UL 2271 in the 2023 release, and below we will discuss some of the notable highlights from the recent changes and additions.

Manual Disconnect: One addition to this standard to enhance safety measures is that an Electrical Energy Storage Assembly (EESA) must be equipped with a manual disconnect. This feature is essential to prevent unintentional access to hazardous voltage components both during servicing and in the event of a collision.

Sodium-ion: One notable change is that sodium-ion batteries now fall under the UL 2271 category. Additionally, sodium cells now have to comply with the cell requirements of 2580, which means that they will have to undergo the same testing requirements as Li-ion cells. Under this suite of amendments, repurposed and second-life batteries will be subject to UL 1974.

High-Rate Charge Test: These latest updates also include the addition of a high-rate charge test that will evaluate the safety of the batteries when the charging rate is higher than the application specification levels. Importantly, unless the BMS has been evaluated as meeting the functional safety requirements under a single-fault failure (see below), OEMs will have to adhere to a charge rate 20% higher than their specifications.

Overload Under Discharge Testing: Another important addition to 2271 is the overload under discharge test, which will replace the “soft short” in the short circuit test. Now you have to run the test at 90% of the current by which the BMS would activate its protection devices. These tests are designed to stress the system by maximizing current to see if the system can handle it and if backup systems come into play.

Single-Fault Failure Testing: Perhaps the biggest update of this standard is the addition of a single-cell failure test for any battery over 1Kwh: a threshold that will likely impact approximately 95% of applications that fall under the LEV category. This single-fault failure is identical to the test outlined in UL 2580 with the stipulation of no explosion or fire outside of the device under test (DUT) for up to one hour after the test. 

The release of the 3rd edition of UL 2271 consists of significant changes such as new battery charge testing requirements, single fault failure testing, the inclusion of sodium-ion batteries, & manual disconnect feature requirements.

These recent changes make it crucial for OEMs & battery designers to consider safety standard requirements from the design stage to mass production. 

What do these updates mean for stakeholders? 

If you already have an existing product with a UL 2271 certification, then the product is grandfathered under the umbrella of the previous version of the standard. However, any design change–from a material change on an external component to updating the battery system itself–will require recertification to the new version of the standard. And of course, all designs going forward must adhere to the updated standard. 

There are several reasons that OEMs and companies designing battery systems for LEVs, especially in the realm of micromobility, should preemptively accommodate the updated standard, tackling the design-system changes necessary for compliance. Local governments and municipalities are passing strict laws surrounding LEVs in the micromobility space in an attempt to ensure public safety. The UL updates were, in part, a response to lawmakers taking up the charge of safety in mobility products and passing laws that ultimately seek more stringent safety standards for these products. For example, in the spring of 2023, after seeing a dramatic increase in fires related to lithium-ion batteries in e-bikes and e-scooters, New York City passed a law requiring all lithium-ion batteries for mobility devices to be certified to UL 2271. As the majority of these e-bike and e-scooter battery systems are not UL 2271 certified in the first place, the burden of certifying is now a requirement by law, rather than industry-wide functional safety standards and guidelines. 

Another consideration is that if a product experiences a failure–even one that is certified to the previous UL 2271 version of the standard–it is likely that an OEM’s insurance company will require testing and recertification to the updated, more stringent standard as a requisite to reduce product liability for coverage. Insurance companies have their own set of interests in product liability contexts, and these interests are often different from the OEMs they insure. 

These changes will undoubtedly have a significant impact on the design and development of energy storage systems in the LEV space–a space that boasts a range of commercial products that are fixtures in the future of electrification. As the energy storage industry continues to evolve, so will the safety standards that govern the industry. Designing and manufacturing to meet and exceed safety standards should not be seen as a challenge, but rather a mission. 

Acculon’s David Ginder, Director of Engineering, was a key contributor to the additions and revisions in the 3rd edition and has decades of safety standard affiliations worldwide. If you are interested in a more in-depth discussion about the scope and breadth of the 2023 UL 2271 updates and the implications therein, please reach out to us!