Letter to UL: Trilateral initiative project on the safety of power banks

February 7, 2023

Mrs. Diana P. Jordan
Chair, Standards Technical Panel for UL 2056, Power Banks
Diana.P.Jordan@ul.org
Underwriters Laboratories Inc.

Mrs. Megan M. Van Heirseele
Project Manager for UL 2056, Power Banks
Megan.M.VanHeirseele@ul.org
Underwriters Laboratories Inc.

Dear Mrs. Jordan and Mrs. Van Heirseele,

This letter summarizes a joint project conducted by the U.S. Consumer Product Safety Commission (CPSC), Health Canada (HC), and the Procuraduria Federal del Consumidor (PROFECO), to analyze and investigate potential fire hazards associated with power banks. We are requesting that Underwriters Laboratories (UL) standards technical panel (STP) 2056, Safety of Power Banks, develop a tri-national^{Footnote 1} safety standard covering power bank products for use in Canada, Mexico, and the United States^{Footnote 2}.

A power bank is a small, portable, battery-powered supply that can power or recharge low-voltage portable electronic devices, such as a mobile phone or a tablet. Power banks have been increasing in popularity in recent years, due to the high power consumption of portable electronics, like smartphones, and the necessity to recharge these devices away from a mains power supply.

Power banks predominantly use lithium-ion cells as their energy source because of their high-energy density, and various form factors. However, as has been well documented, lithium-ion chemistries also pose a risk of fire and explosion if the cells are overcharged, physically damaged, or poorly manufactured. There have been reported incidents with power banks that resulted in thermal burns, smoke, fire, and explosions.

U.S. - 5,726 reported incidents (unfiltered)^{Footnote 3}

An incident occurred in the U.S. where a consumer fell asleep on top of her bed with a power bank charging her phone. Sometime later the power bank began to overheat and emit smoke, burning through the blanket, comforter, and the top of the mattress. When the consumer woke up she unplugged the charger and poured a water bottle on the power bank, burning her hand in the process.

Canada - 88 reported incidents^{Footnote 4}

A consumer reported in Canada that the power bank they purchased had been charged and used previously. The consumer planned to return the product due to its large size and weight. They placed the power bank in a basket in their bedroom, along with other goods to be returned. They heard a loud bang and then the smoke alarm. The power bank had exploded and items surrounding it within the basket had caught on fire. The consumer was able to smother the flames with a blanket and pour a bottle of water over it. The consumer suffered burns and developed blisters and had melted plastic stuck to their arm. Subsequently, they visited the hospital emergency room for treatment. The small fire caused damage to the contents of the basket and damage to the bedroom. The incident was reported to fire officials and the insurance company.

PROFECO National Consumer Protection Laboratory (LNPC) performed studies in 2015 and 2018, as part of the agency's annual quality study programs. Evaluations of marking, heating during recharge, heating during discharge, characterization of the power bank, and verification of the capacity were performed. The results of these studies determined that the temperature increase during discharge in normal use was higher than 30°C, which may represent a risk for the user. Similarly, in the recharge heating test, temperature increases between 10°C and 20°C were found, which, although not representing a risk of severe injury, could cause some discomfort to the user. Regarding the verification of the capacity, the studies found that, on average, the real capacity of the power banks is 62.30 percent of the stated value. These results were published in issues of PROFECO's Consumer Magazine^{Footnote 5} in March 2015^{Footnote 6}, and February 2019^{Footnote 7}.

In 2018, staff from the CPSC, HC, and PROFECO initiated a tri-national project to review the safety of power banks. These high-energy density devices are widely used, and the project team recognized the importance of these products to be properly designed and certified as much as the electronics devices they are charging.

Consequently, CPSC, HC, and PROFECO conducted a joint test program to analyze and investigate potential fire hazards associated with power banks by testing products purchased from the markets of the three countries. Each country evaluated the products that they purchased using a mutually developed test plan, based largely, but not exclusively, on the requirements in UL 2056 Outline of Investigation for Safety of Lithium-ion Power Banks. Appendix A is the test plan that the agencies developed and used.

Appendix B includes a summary of the results of the testing from the three countries. Most of the products successfully passed typical electrical testing (e.g., normal charge, normal discharge, overload, and short circuit), as well as environmental conditioning, impact, drop, and crush testing. There were inconsistences in the flammability performance of the enclosures in response to open flame and glow wire. Despite the acceptable performance of the tested samples, the tri-national team believes that the safety of these useful and abundant products would benefit from a tri-national consensus standard and requests STP 2056 to work towards the creation of a consensus North American standard for Canada, Mexico, and the United States, incorporating appropriate safety requirements, including those identified collectively by the agencies.

Each party appreciates the work of UL in developing UL 2056 Outline of Investigation for Safety of Lithium-ion Power Banks but encourages the STP to move forward in developing a tri-national safety standard covering power bank products to advance the safety of power banks in North America. All three organizations are willing to contribute to the development of the standard.

Please contact the agencies if you have any questions or need clarification of this request. Thank you for your efforts to promote safety.

[Signature CPSC]
Duane Boniface
Assistant Executive Director for Hazard Identification and Reduction
U.S. Consumer Product Safety Commission, United States of America

[Signature HC]
Dennis Price
Acting Director General, Consumer and Hazardous Products Safety Directorate, Healthy Environments and Consumer Safety Branch
Health Canada, Government of Canada

[Signature PROFECO]
Hugo López
Deputy Compliance Attorney
Federal Consumer Attorney's Office, United Mexican