SEARCHING FOR A SOLUTION TO E-BIKE FIRES

The lithium-ion battery fire issue in New York City has garnered a lot of attention, and rightfully so. Unfortunately, New York City’s misfortune is spreading to other municipalities, both in the United States and internationally.

This crisis highlights many aspects, some good and some bad, of the emerging category of micromobility within the worldwide transportation infrastructure.  Micromobility, e-bikes in particular, can and will help combat many critical issues that we as a global community are working hard to address, climate change being the most crucial. 

But efficient and reliable e-bikes require the carriage of energy-dense power supplies.  Lithium-ion batteries are lightweight, compact, and incredibly energy-dense.  Being lightweight and compact are critically important attributes for use with a powered two-wheeler.  Properly designed, manufactured, used, and charged lithium-ion battery packs are ideal for this application.  Lithium-ion batteries enable the storage of sufficient energy, and the delivery of sufficient power, to make e-bikes practical and useful for any number of personal transportation missions.

It’s no surprise that lithium-ion batteries are the energy source of choice, at least for the foreseeable future, for these important and useful vehicles.

However, poorly-designed battery packs, using sub-standard battery cells, assembled without due care, utilizing poorly-designed battery management systems, charged by incompatible battery chargers, and abused in service, are susceptible to catastrophic failure, primarily due to thermal runaway and subsequent fire.

Poorly-designed and manufactured battery packs subjected to extremely harsh service conditions are the root cause of the New York fire crisis.

Lithium-ion battery fires are incredibly dangerous.  They generate temperatures exceeding 2500°F.  They generate copious quantities of extremely toxic gases including hydrogen fluoride, hydrogen cyanide, and carbon monoxide.  An e-bike battery pack is comprised of numerous individual battery cells that can become dislodged from the battery pack and jet around, being propelled by the gas venting from the cell like small rocket engines, igniting secondary fires as far away as 10 to 15 meters (33 to 50 feet) from the failing battery pack.

Lithium-ion battery fires are almost impossible to extinguish.  Water will not extinguish a battery pack fire. It can only serve to slow propagation.  Once a battery fire appears to have been extinguished, residual energy remaining in affected cells can reignite, causing the original fire to perpetuate. 

On balance, an e-bike battery fire not only presents a significant life-threatening danger to users and bystanders, but also to the first responders and firefighters charged with dealing with them.

Therefore, the development and implementation of short- and long-term solutions to this issue is of paramount importance.

A long-term solution is already in process.  As stated above, quality battery packs are significantly less likely to fail catastrophically.  If a quality battery pack is properly charged and used in service, the chances of a dangerous failure are almost zero.

Our primary task then becomes ensuring that only quality battery packs are developed and distributed for use here and abroad. 

Safety standards for lithium-ion batteries have been developed and promulgated by competent agencies, most notably, Underwriters Laboratories (UL).  When a pack is designed and manufactured such that it complies with the requirements of UL standard UL 2271, that battery pack can be relied upon (when properly used and maintained) to deliver safe and reliable service for the duration of its useful life.

However, UL 2271 is a voluntary standard.  But the crisis in NYC, having drawn the attention of local, state, and federal regulators, has stimulated the promulgation of current and pending laws requiring that all micromobility battery packs be tested and certified compliant (by Nationally Recognized Testing Laboratory) with UL 2271 before they can legally be sold as original equipment and/or replacement battery packs for e-bikes.

These laws, when enforced, will ensure that this crisis will ultimately end.  But until such time that the hundreds of thousands of substandard, poor-quality battery packs currently in circulation are purged from use in this country and elsewhere, the problem will persist.

Efforts to eliminate dangerous packs are under discussion.  However the proposals to date are expensive, face difficult logistical hurdles, and will take significant time to implement.

What can we do in the meantime?

It has been suggested that since ending catastrophic battery failures is a long-term goal, our short-term efforts should be directed toward mitigating the effects of the battery fires that we know will occur in the interim.

The most promising strategy (from my perspective) is the development and installation of safe battery pack charging and storage cabinets, and the implementation of battery charging stations using safe storage cabinets and/or other means of containing a battery fire when it occurs.  While feasible from a technological point-of-view, these too will be expensive and relatively slow to implement.

It has been suggested that widespread distribution of “battery bags” to users (primarily delivery people, the biggest group of sub-standard battery pack users in NYC) represents a potential short-term solution.

A battery bag is a bag or pouch fabricated from high-temperature and flame-resistant fabric.  The proposed use would be to store and charge e-bike batteries in the battery bag, so if a fire occurs, the battery bag could contain the flames and heat generated by a battery fire. While unable to contain the toxic gas generated by a battery pack, it is thought that the benefit to the at-risk personnel in the vicinity would be to buy time to safely evacuate the area and to give first responders time to intervene.  Further, the battery bag would hinder fire propagation to the structure adjacent to the failing battery pack.

However, a recently published report titled “Evaluation of Fire Spread and Suppression Techniques in Micro-Mobility Battery Packs” calls that mitigation strategy into question.

The testing described in this report was conducted in conjunction with a very reputable engineering R&D laboratory, Exponent.  I have worked with Exponent in the past and can attest to their excellent engineering and scientific expertise and testing capabilities.

The testing, as the report title indicates, evaluated several fire suppression techniques, including the use of a fire blanket.  The test results indicated that the use of a fire blanket exacerbates the severity of the battery fire.  The blanket apparently hinders heat transfer, resulting in a hotter fire that accelerates cell-to-cell propagation, resulting in a significantly more dangerous situation.  Further, the blankets tested were not able to withstand the significant temperatures generated by the battery fire, and the fire actually breached the blankets.

This test did not evaluate “battery charging bags.”  But one could extrapolate the results of the blanket test to battery bags given that the use of a bag would present a similar scenario with respect to trapping the heat generated by a burning battery pack, accelerating cell-to-cell propagation, thus worsening the fire.

The good news, from the e-bike industry perspective, is that the testing validated the efficacy of a battery fire mitigation strategy that our industry has been investigating for some months.  The tests discovered that by insulating individual 18650 cells in the pack from one another, using a resin introduced into the pack during manufacture (or other insulating media) precluded cell-to-cell propagation.  In that manner, if a single cell were to fail, the fire would not propagate to other cells in the pack, resulting in a relatively benign failure.

I anticipate that this mitigation strategy will be adopted by the industry after further evaluation.  Unfortunately, this effective solution does not represent a short-term solution and does not help the current New York situation.

I must advise that this is just one test.  These conclusions are subject to further evaluation and peer review.  Further, not much detail was given regarding the actual construction of the blankets evaluated.  Perhaps there are blankets available from other sources that would have done a better job resisting burn-through.  Further, this test, as stated, did not evaluate battery bags.  But the “trapped heat accelerating propagation” mechanism would still be present.

The propensity of the blanket to trap heat and accelerate propagation will be consistent with the battery bag fire suppression technique.  Assuming that a battery bag would exacerbate the situation is logical and sound engineering speculation.

The test report referenced above can be found at: 

https://iopscience.iop.org/article/10.1149/2754-2734/ad1a72/pdf

There are no formal safety standards nor recognized testing protocols that evaluate the efficacy of battery charging bags.  UL has recently formed UL Technical Committee UL 1487, charged with formulating safety standards for “battery containment enclosures.”  I plan to petition this technical subcommittee to include battery bags in their deliberations.

In the meantime, I strongly urge anyone considering the use of a battery storage bag reconsider that plan until such time as formal testing is performed to determine their effectiveness in mitigating the severity of failing e-bike battery packs.

Contact Mike Fritz, mike@humanpoweredsolutions.com.

MIKE FRITZ ADDRESSES SAFETY COMMISSION ON BATTERY SAFETY

The following is a transcript of remarks from Mike Fritz, chief technology officer for Human Powered Solutions, to the Consumer Product Safety Commission as part of the July hearing on battery safety related to e-bikes:

My name is Mike Fritz. I am the chief technology officer for Human Powered Solutions. We are a consultancy specializing in the micromobility industry, with specific focus on bicycles and electric bicycles.

Human Powered Solutions is currently on retainer to the National Bicycle Dealers Association (NBDA). We advise the NBDA on many issues associated with bikes and e-bikes, not the least of which is the battery fire issue that is the focus of this meeting.

A brief overview of my credentials. I earned a Bachelor of Science degree in mechanical engineering from Marquette University in 1973, and a Master of Engineering Management from Northwestern University in 1985.

I have spent the bulk of my professional career in the bike and e-bike industries. I joined the Schwinn Bicycle Company immediately after college in 1973, holding positions in machine design, product safety, research and development, and engineering management. Upon leaving Schwinn in 1990, I worked in engineering management and product development capacities at Huffy Bicycles, Brunswick Bicycles, and Pacific Cycles. In 1998, I was hired by Lee Iacocca as VP of Engineering and Product Development, and charged with the responsibility of developing and sourcing electric bicycles for his nascent company, EV Global Motors.

During my tenure at EV Global Motors, Mr. Iacocca was persuaded to try lithium-ion batteries as the energy supply for the e-bikes we were developing. This was in the year 2000. I knew relatively little about lithium-ion battery chemistry at that time, so of course I supported and implemented Mr. Iacocca’s decision. After receiving reports of battery fires in our e-bikes, in cooperation with CPSC we launched a product recall to retrieve those batteries from our customers. Through investigation, we learned that the cause of these failures was the fact that we were using high-energy density, low-power density cells in an application that required high-energy density, high-power density cell attributes. High-energy, low-power density batteries are great for cell phones and laptops but are dangerous in mobility applications where power is critical to function and performance. We found that we were significantly overstressing the batteries, leading to thermal runaway and catastrophic failure. Fortunately, there were no injuries or deaths associated with this situation.

But this experience led to my devoting a considerable portion of my subsequent career to the safe adaptation of this marvelous technology in micromobility applications.

The advent of high-energy, high-power density lithium-ion battery chemistry adaptable to the form factor commonly used in electric mobility applications is the energy storage breakthrough that has led to the development and rapid proliferation of electric mobility devices. Lithium-ion batteries enable the storage of sufficient energy and the delivery of sufficient power to make electric cars and micromobility devices practical and useful for any number of transportation missions.

However, lithium-ion batteries, like any energy-dense storage medium, carry risks associated with the uncontrolled release of the energy they hold. Gasoline is an excellent analogy. Careless storage, use, or handling of gasoline can result in tragic consequences. But we have learned how to safely utilize the latent energy in gasoline. Since the onset of practical automobiles, and until just recently, gasoline has been the energy storage media of choice for most of our mobility needs. We have learned how to benefit from gasoline in a multitude of applications.

Fortunately, we have developed a comparable level of competence with respect to our management of the energy contained in these lithium-ion batteries. We know how to engineer, manufacture, assemble, and integrate these batteries into our mobility devices. Properly designed, produced, and used lithium-ion battery packs are safe and reliable for this incredibly important application, with a very low probability of catastrophic failure. When they do fail, it is usually due to misuse, damage, or other factors that are out of our control.

However, this remaining probability of failure is sufficient to require protocols, policies, procedures, infrastructure, training, and education to ensure the safety of the supply chain, including retailers. Compliance standards, testing, and certification are essential to both retailers and consumer safety, including warnings, owner’s manuals, and education. As the Fire Department of New York already knows and is advocating – lithium-ion battery fires have “changed the game” relative to how the professionals fight lithium-ion battery source fires.

Since leaving EV Global Motors, I have acted in engineering management roles for several electric bike companies including American Electric Cycles & Fitness, Ultra Motor, and Pedego. I have acted as a consultant to e-bike battery pack manufacturers including Taiwan-based TD High Tech Energy Corporation, China-based Phylion Battery Company, and DLG Battery Company.

My responsibilities associated with these companies oftentimes involved investigating lithium-ion battery pack failures resulting in catastrophic fires. I have seen, up-close and personal, the aftermath of these failures. I have participated in battery fire analysis at world-class engineering laboratories including Exponent and National Bureau of Standards.

Fortunately, the companies with which I have been associated produce high-quality battery products. However, as noted above, even the best battery packs can fail under certain circumstances, usually out of the control of the pack makers. These failures have been rare, and closely analyzed.

I have been particularly focused on the fires occurring in New York City. I attended the symposium sponsored by FDNY in September 2022. I witnessed the failures induced by FDNY to graphically demonstrate the destructive power of the uncontrolled, spontaneous release of the energy contained in an e-mobility battery pack. I have had numerous conversations and a follow-up meeting with FDNY since. I have volunteered my services as a liaison between FDNY and the e-bike industry given my experience and network within the industry.

Those of us in the e-bike industry that recognize and embrace our responsibility to provide quality products have an excellent track record of providing safe products to our customers. Batteries used in quality products rarely fail catastrophically.

Unfortunately, not everyone in this business brings the diligence and care necessary to develop safe, lithium-ion battery-powered micromobility products.

It is my opinion that the battery fire issue in New York City is the result of distributors importing and selling cheap electric bicycles that use poorly engineered, poorly constructed lithium-ion battery packs utilizing sub-standard, defective battery cells. Further, these packs are utilized under harsh service conditions, abused by using mismatched battery chargers, and are serviced by individuals not qualified to perform such service.

Looking in retrospect, we have failed to implement appropriate mandatory standards, use and safety protocols, and broad-based education for our constituencies necessary to ensure the safe and reliable utilization of this remarkable energy storage technology.

This lack of oversight has allowed the introduction of dangerous e-mobility products into our streams of commerce. We have failed to implement controls to block the importation of substandard battery products by unscrupulous distributors more interested in profits than consumer safety. We have failed to design and implement a distribution infrastructure that can mitigate and contain the effects manifest when one of these packs fails.

I clearly have a vested interest in the widespread adoption of e-bikes. I have devoted the bulk of my career to the development and refinement of these marvelous machines.

Society in general also has a vested interest in the adoption of these clean and efficient vehicles as we combat our current climate change crisis. E-bikes can and will make a difference as we move from cars to e-bikes for personal, short-range transportation needs.

But the situation in New York threatens to slow the adoption of light electric transportation and delay the benefits associated with their widespread usage. This situation involves a very small segment of this industry. But negative news coverage of the tragic consequences of the failures of substandard battery packs is creating concern in the minds of our prospective customers, which is certainly understandable! What consumer wants to buy a product that threatens the safety of their home and loved ones?

Action is required now. The only effective short-term solution to the battery fire issue is to purge these poor-quality, dangerous packs from circulation and use in NYC and elsewhere.

Beyond immediate action, Human Powered Solutions will continue to support the National Bicycle Dealers Association with its efforts to raise awareness of these issues and its work to develop and circulate best practices for dealing with lithium-ion batteries in their retail outlets. We will continue to support the NBDA as it lobbies for the development, promulgation, and enforcement of appropriate standards. We will continue to support the NBDA as it further lobbies for revision of our current ‘di minimis’ rules as they relate to the ability to import products that represent a substantial hazard to American micromobility consumers.

I am available for questions and further discussion.

Contact Mike Fritz: mike@humanpoweredsolutions.com

JAY TOWNLEY RECOGNIZED FOR DEDICATION TO IMPROVING THE BICYCLE INDUSTRY

At the CABDA Midwest Expo Awards Ceremony February 7, Jim Kersten, CABDA show director, presented a special award to 66-year industry veteran and founding partner of Human Powered Solutions, Jay Townley, for dedication to improving the bicycle industry.

In presenting the award, Kersten said, “CABDA doesn’t give out special awards often, but in this case Jay Townley has been a supporter of our expos from the beginning, and he has written articles and conducted webinars for the NBDA, and made presentations at CABDA Expos, including for our education sessions today, and will be making a presentation at our East Coast Expo March 7 and 8 at the Meadowlands in New Jersey.”

In accepting the award, Townley said, “I am surprised and honored. Being in the bicycle business as long as I have I no longer expect awards, but when there is recognition like this for continuing to do the best I can for this business, I am very grateful. My thanks to Jim Kersten, the whole CABDA family and crew.”

Jim Kersten, left, recognizes Jay Townley for industry service.

IMPORTANT NOTICE TO ALL E-BIKE DEALERS LOCATED IN FLORIDA STORM RAVAGED AREAS

Be aware:  lithium-ion battery packs used to power electric bicycles and scooters suffer damage that will compromise their safety and stability if partially or totally submerged in water.  This damage can be even more severe if the battery packs are submerged in salt water, as you would expect from storm surge associated with Hurricane Ian.

Please check your inventory.  If you have battery packs that have been partially or totally submerged in flood water during the storm, we advise that you carefully remove all affected battery packs to a safe location outdoors, such as a parking lot, away from your store and any other flammable materials.

We urge that you notify your local fire department that you have a quantity of potentially dangerous lithium-ion battery packs giving the fire department the exact location of the battery packs.

Solicit advice from the fire department as to what to do next.

The e-bike industry’s recycling partner, Call2Recycle, is available should you need help with safely handling damaged E-Bike batteries. Please reach out to ebikeprogram@call2recycle.org if you need assistance. 

Please stay tuned for further advice.

THE IMPORTANCE OF PRODUCT LIABILITY INSURANCE FOR THE E-BIKE RETAILER

Anyone in the e-bike space, be it an e-bike retailer, distributor, brand, etc., is aware that there is a major problem facing the e-bike industry.  That problem is the occurrence of potentially catastrophic lithium-ion battery fires.

Lithium-ion batteries are the technological breakthrough that has enabled the development and proliferation of clean electric vehicles into our worldwide transportation infrastructure.  Lithium-ion battery chemistry enables the storage of sufficient quantities of electrical energy, and the ability to deliver that energy with sufficient power to provide the range and torque necessary to propel vehicles from commercial trucks to electric bicycles in all sorts of practical transport modalities.

However, such high energy storage density presents a risk if the stored energy in a battery pack is released in an uncontrolled fashion.  Unfortunately, there are several battery failure modes that do result in the uncontrolled release of energy in the form of a very hot fire that generates copious quantities of poisonous gas and is almost impossible to extinguish.

Fortunately, the frequency of these failures as a percentage of batteries in use is very low.  However, with the rapid proliferation of e-bikes, due in part to their utility as a personal transportation, the occurrence of these fires is on the rise.  Further exacerbating the situation is the fact that there are many unscrupulous importers importing cheap, sub-quality e-bikes to take advantage of the surge in demand for these remarkable products.

Sadly, significant property damage and loss of life have occurred due to e-bike battery packs failing in the field.

Industry is doing much to address this issue.  A safer lithium-ion battery chemistry that will all but eliminate catastrophic battery failure is in the works.  However, batteries featuring this new chemistry will not be commercially viable for at least three to five years.

It is expected that federal, state, and municipal governments will promulgate regulations requiring that e-bike electrical systems, including their lithium-ion batteries, comply with existing, voluntary safety standards that have been published by credible agencies with significant insight and understanding of the conditions that initiate catastrophic battery failures.  It is commonly known that low-cost, poor-quality battery packs are most likely to fail.  These safety standards, once mandated, will go a long way to keeping substandard packs from the marketplace.

Given that regulations of this nature take a long time to develop and implement, the National Bicycle Dealers Association (NBDA) is recommending that its member dealers, as well as ALL e-bike retail dealers, source electric bikes only from suppliers that can and do provide documentation of compliance with the now voluntary e-bike safety standard, UL2849.  E-bikes that comply with UL2849 are significantly less likely to experience a lithium-ion battery failure, as the standard assures that the battery pack has been designed, manufactured, tested, and certified to the highest product standards currently available.

However, compliance with the standard does not absolutely guarantee that a battery failure will not occur.  Conditions that may lead to a battery failure can be introduced through misuse in service.  Improper charging, physical damage to the pack, and allowing a pack to sit in a fully discharged condition for an excessive period, are all service life experiences that can compromise the safety and stability of even the best lithium-ion battery packs.

In cooperation with Human Powered Solutions, NBDA has developed and promulgated best practices for e-bike retail establishments and e-bike consumers that provide guidelines that, when followed, help avoid the introduction of these potentially dangerous conditions.

Nevertheless, even under the best conditions, a lithium-ion battery fire can happen.  The potential damage, injuries and, in the worst case, loss of life, will inevitably result in liability claims made by those impacted by a battery failure.  Therefore, it is incumbent on every e-bike retailer to protect their business and livelihood with a comprehensive product liability insurance policy written by a top-tier insurance company.

It is also incumbent on every e-bike retailer to require that their e-bike product suppliers show proof that they also have quality liability insurance in effect.  Just as every dealer must require that each of their vendors are delivering products in compliance with UL2849, dealers should insist on seeing copies of the liability policies held by those same suppliers.

In cooperation with NBDA, HPS will be offering more specific guidelines to dealers in this regard.  We are consulting with quality insurance brokers and insurance companies to better understand how retailers can effectively protect their business in the event an unfortunate incident impacts one or more of their customers.

Please stay tuned for more important advice.

Questions? Contact Mike Fritz, mike@humanpoweredsolutions.com.

AN OPEN LETTER TO E-BIKE BUYERS AND USERS REGARDING LITHIUM-ION BATTERIES

Editor’s note: with all the recent discussion about e-bike battery safety within the trade, another very important constituency that needs to be aware of potential issues is e-bike owners. Mike Fritz, chief technology officer with Human Powered Solutions, has created this “open letter” for retailers and others to use as a guideline for educating their customers about best practices related to e-bike battery and charging safety.

—–

Congratulations on joining the Micromobility Revolution! You are about to discover the benefits of enhanced personal mobility while improving your physical fitness and rediscovering the joys of cycling.

E-bikes are simple yet sophisticated marvels of engineering. They are lightweight and powerful. Most importantly, they take advantage of a very important development in energy storage through chemical engineering, the lithium-ion battery.

Lithium-ion batteries enable the storage of sufficient energy and the delivery of sufficient power to make e-bikes practical and useful for any number of personal transportation missions. 

However, lithium-ion batteries, like any energy-dense storage medium, carry some risk associated with the uncontrolled release of the energy they carry. We are all aware of fires associated with products that utilize lithium-ion batteries for their energy storage needs. E-bikes are no exception.

While significant work is being done by scientists and engineers working in laboratories all over the world to eliminate the causes of these fires, certain actions on the part of users of products using these batteries can significantly diminish the likelihood of a fire, and mitigate the effects of such a fire in the unlikely event they experience a battery failure.

This document is intended to be a guide for consumers regarding the safe use, charging, maintenance, and storage of the lithium-ion batteries that power their e-bikes.

Please know that the chances of your e-bike battery failing in a catastrophic manner are miniscule, but the potential ramifications of such a failure are so significant that these relatively simple precautions are more than justified.

BATTERY SAFETY BEST PRACTICES

  • Only use the charger that was supplied with your e-bike. NEVER attempt to charge the battery pack with a different charger or power supply.
  • Do not open or otherwise tamper with your battery pack. There are no user serviceable parts inside the battery pack. Opening the pack will void the warranty and could cause a serious problem leading to a fire.
  • Charging the battery pack on the e-bike is preferred. However, if you charge the battery pack off the bike, place the pack on a non-flammable surface, like a concrete floor, away from flammable materials, before starting to charge it.
  • Charge the battery in an area with a working smoke detector.
  • NEVER CHARGE THE BATTERY UNATTENDED OR UNATTENDED OVERNIGHT.
  • If the battery pack overheats, or if you notice an odor, smoke, or odd noises coming from the battery pack, and if it is safe to do so, move the pack away from flammable materials, preferably outdoors, and call 911.
  • Monitor the battery and charger during the charging process. When the charger indicates that the battery is fully charged, unplug the charger from the wall outlet and disconnect it from the battery pack.
  • Do not leave the charger ON and connected to the battery pack indefinitely.
  • For extended periods of non-use, store your battery pack in a clean, dry environment away from flammable materials.
  • Store the battery pack at temperatures between 40℉ to 100℉ (4.5℃ to 38℃).
  • Battery packs are best stored at 50% capacity. Recharge the pack for 60 minutes every other month to prevent deep discharge.
  • If the battery is dropped or damaged, or immersed in water, DO NOT ATTEMPT TO CHARGE IT. Store it in a safe place, preferably outdoors, until it can be taken to a shop to be inspected.
  • E-bike shops participating in the Call2Recycle recycling program are trained to identify damage that renders a battery pack potentially dangerous, and how to dispose of a battery in a dangerous condition.
  • When your battery pack reaches the end of its useful life and can no longer hold a sufficient charge, return it to your dealer for recycling.
  • Replace an end-of-life battery pack with a replacement pack provided by the original supplier of your e-bike.
  • DO NOT ATTEMP TO HAVE YOUR ORIGINAL PACK ‘REFURBISHED.’
  • DO NOT REPLACE YOUR BATTERY PACK WITH A PACK FROM A 3RD PARTY SUPPLIER.

Disclaimer:  You assume all responsibility and risk for the use of the safety resources available on or through these guidelines. Human Powered Solutions, LLC (HPS) does not assume any liability for the materials, information and opinions provided on, or available through these guidelines. No advice or information given by HPS shall create any warranty. Reliance on such advice, information or the content of these guidelines is solely at your own risk, including without limitation any safety guidelines, resources or precautions related to the development or installation of battery storage and charging stations, battery storage and battery charging protocols, or emergency procedures, or any other information related to safety that may be available on or through these guidelines. HPS disclaims any liability for injury, death or damages resulting from the use thereof.

Contact Mike Fritz: mikefritz@humanpoweredsolutions.com

UPDATE: SAFE CHARGING AND STORAGE OF LITHIUM-ION BATTERIES IN THE E-BIKE RETAIL ENVIRONMENT

The growth of the electric bicycle segment of the bicycle industry has been nothing short of remarkable. The pandemic, the environmental crisis, and soaring energy costs have all combined to highlight and magnify the importance of light electric vehicles in the transportation infrastructure.
 
Lithium-ion batteries represent the most significant technology breakthrough that has enabled the development and manufacture of practical electric vehicles, including e-bikes.  The high gravimetric and volumetric energy density of lithium-ion batteries make them most suitable for use in transportation applications. These batteries store sufficient energy to power electric vehicles over meaningful distances.   They can deliver the significant power required to accelerate heavy loads to useful speeds.
 
These batteries are the first viable alternative to gasoline as the energy supply of choice for practical, day-to-day electric transportation.
 
However, as is the case with gasoline, the storage of energy required by electric vehicles carries significant risk. The uncontrolled release of stored energy is dangerous and can have catastrophic consequences. One can imagine the unpleasant scenario resulting from tossing a lit match into a bucket of gasoline. There is a comparable analogy with lithium-ion batteries as it relates to the uncontrolled release of energy.
 
Certain attributes of lithium-ion batteries make them susceptible to catastrophic failure under certain predictable circumstances.  Manufacturing defects, inadequate or improperly programmed battery management systems, service requirements that exceed battery design tolerances, improper charging protocols, physical damage, etc., lead to battery failures that can precipitate a fire.  Due to the chemical composition of the liquid electrolyte used in a lithium-ion battery, such fires burn extremely hot, generate great quantities of toxic gasses and are very difficult to extinguish.
 
To date, incidents of catastrophic lithium-ion battery fires are relatively rare.  But given the explosive growth of the e-bike market in the U.S. and elsewhere, and the proliferation of low cost e-bikes likely equipped with substandard, uncertified battery packs, there is great concern that the frequency of these unfortunate events is going to increase.  The potential for property damage, and the risks of personal injury and death, will also rise.
 
As advocates for the growth and commercial success of electric bicycles, we offer the following guidelines to e-bike dealers to ensure proper storage and charging of e-bike lithium-ion battery packs in their retail environments.  These guidelines are intended to minimize the possibility of a battery pack failure, and to mitigate the danger and resulting damage that will occur in the event a failure does occur. 

  • Procure a fire-resistant cabinet.  Appropriate cabinets are available at many industrial supply outlets (like McMaster-Carr, Grainger, etc.) or Amazon.com.
  • Position the cabinet away from flammable materials (cardboard, boxed inventory, lubricants and/or chemicals) in your shop.  Mount a smoke detector (preferably a networked smoke detector connected to the store’s security system) in proximity to the cabinet.  Mount a Class A, B, C fire extinguisher in proximity to the cabinet.
  • Store all lithium-ion e-bike battery packs in the fire-resistant cabinet. 
  • Store new e-bike battery packs in their original cartons in the fire-resistant cabinet.  DO NOT pre-charge battery packs.  Only charge a new pack just prior to delivering a new e-bike to a customer.
  • Store the battery pack from an e-bike brought in for service in the cabinet until such time as it’s needed for testing the serviced e-bike, or the e-bike is being returned to the customer.
  • Ensure all lithium-ion e-bike battery packs are stored in the cabinet whenever the store is closed or otherwise unattended.

Safe Charging of E-bike Battery Packs in the E-bike Shop:

  • Procure a wire rack to use as a charging stand for e-bike battery packs.  Suitable racks are available at many industrial supply outlets (like McMaster-Carr, Grainger, etc.) or Amazon.com.  Preferably, procure a wire rack equipped with wheels for easy maneuvering.  Procure a set of extreme heat-protection gloves and store them nearby the battery charging rack.
  • Position the cabinet away from flammable materials (cardboard, boxed inventory, lubricants and/or chemicals), in proximity to the smoke detector and the fire extinguisher.
  • If possible, position the battery charging rack near a door leading outside of the shop.
  • Procure a 32-gallon industrial trash can.  Position it near the charging rack.  Fill it about 3/4 full of water.
  • Procure additional battery chargers for the various battery packs supplied with e-bikes sold through the store.  Fix these extra chargers on the wire rack (with zip ties or other means) and connect them to a switched power strip also attached to the rack.  These extra chargers are to eliminate the need to use the new charger shipped with the e-bike.
  • ONLY USE CHARGERS INTENDED FOR THE SPECIFIC BATTERIES SOLD BY THE SHOP.  Never use a charger not supplied by the e-bike distributor or a DC power supply to charge e-bike batteries.
  • Only charge batteries on the charging rack.  Never charge a battery pack inside the fire- resistant cabinet.
  • Charge e-bike battery packs just prior to the delivery of the new e-bike.
  • NEVER CHARGE A LITHIUM-ION BATTERY PACK UNATTENDED.  Lithium-ion batteries most often fail during charging.  There are noticeable indications from a pack as it starts to fail.  If there is an attendant present, actions can be immediately taken to deal with the pending failure.
  • When the battery charger indicates that a battery pack is fully charged, turn off and then disconnect the charger from the battery pack.  Return the battery pack to the cabinet until just prior to delivery.

IN CASE OF EMERGENCY:

  • If a battery starts smoking, making noise or showing signs of melting plastic:
    • If it can be done safely, using the heat protection gloves, disconnect the failing battery pack from the charger and place it in the water-filled trash can.  Otherwise, move the failing pack outside away from any flammable materials.
    • If the failing battery pack cannot be safely removed from the charging rack, disconnect the power strip from the electrical outlet and push the charging rack outside.
    • If it can be done safely, disconnect any other battery packs that are on the charging rack from their respective chargers, move them off the charging rack away from the failing pack, and return them to the fire-resistant cabinet.
  • Call 911 to summon the fire department.
  • Other than immersing the pack in water or moving it out of the shop to a safe place, do not try to extinguish the burning pack.  You will not be able to do so.  The recommended fire extinguisher is there to extinguish any secondary fires that may be ignited by the burning pack.
  • Evacuate the store and wait for further instructions from the fire department.

Issues and Discussion:

  • Concern:  In a large store with many e-bikes in inventory, it may be deemed impractical to remove every battery from every bike box and store them in the fire-proof cabinet.  Or there may be too many batteries in inventory to store in a single cabinet.
    • We understand.  It’s an inventory logistics problem.   While it’s highly unlikely, new lithium-ion batteries can fail spontaneously.  It’s always preferable to store all e-bike batteries in the fire-resistant cabinet.  If necessary, procure additional cabinets to store as many batteries as possible.
    • Mitigating factors are that batteries packed with new e-bikes in their shipping cartons are obviously not being charged and are in a partially discharged condition.  The likelihood of one failing under those conditions is low.  However, new batteries in a partially charged condition have failed in transit, so there’s no guaranty.
  • Concern:  What about e-bikes equipped with the battery housed in the down tube that is difficult and/or time consuming to remove?
    • Remember the Cardinal Rule:  NEVER charge batteries unattended.  Batteries usually fail while being charged.  Charge those e-bikes with an attendant present in an open area away from flammable materials in the shop.  If the pack sends signals that it’s failing, wheel the e-bike out of the store to a place away from flammable materials and call the fire department.
    • When storing e-bikes with integrated batteries while the shop is closed, position those e-bikes DISCONNECTED FROM THE CHARGER in an open area away from flammable materials.  This is when a networked smoke detector pays for itself.
  • Why the water filled trash cans?
    • E-bike lithium-ion battery packs are comprised of a quantity of small (approximately AA-battery size) cells, wired in a configuration to yield the voltage and capacity requirements of the e-bike they are design to power.  Depending on the voltage rating and capacity of the battery pack, there may be as many as 84 of these cells contained in the pack.
    • When an e-bike battery fails, it starts with a single cell.  The cell enters a condition called thermal runaway resulting in boiling of the cell’s liquid electrolyte which over-pressures the cell casing causing a relief valve to open.  When the relief valve opens, the hot gas that results from the boiling electrolyte vents at high pressure and velocity.
    • This gas is very flammable and invariably catches fire as it’s vented from the cell.  The cell in effect becomes a mini-blow torch.
    • The failing cell then causes adjacent cells to overheat, resulting in a chain reaction as one cell after another overheats and vents the flammable gas.
    • The net result is an extremely hot fire that generates significant quantities of toxic smoke.  The fire is virtually impossible to extinguish. 
    • The reason we recommend submersing a failing pack in a trash can filled with water is to attempt to interrupt fire propagation by cooling the remaining cells in the pack thus preventing further propagation.  A fire involving a few failed cells is significantly less dangerous than a fire involving 84 cells.
  • The water immersion strategy to interrupt fire propagation has been called into question as an effective e-bike battery fire mitigation strategy.  However, this method has been adopted by several European fire departments to control electric car battery fires.  The fire department positions a car-size container of water near a burning car, and then uses a forklift or crane to immerse the car in the water.  We are confident that this method will be effective in mitigating e-bike battery fires.  Nevertheless, Human Powered Solutions is working with a battery pack manufacturer and an accredited testing laboratory to validate this method.  We will advise the industry of our test results when available.
  • This issue will not be with our industry forever.  Solid state lithium-ion batteries are in development that will eliminate the potential for lithium-ion battery fires.  It is expected that solid state lithium-ion batteries will be commercially available for use in electric bikes in the next three to five years.  Solid state batteries offer the added benefit of higher energy density resulting in greater e-bike range and utility.
  • Additional methods to reduce the possibility of e-bike battery fires rest with each e-bike retailer.  Be proactive with your suppliers.  Only buy electric bicycles from vendors that have (a) sourced high quality battery packs from reputable pack suppliers, and (b) supply copies of certification documentation proving that the packs supplied with the bikes you sell have been tested and comply with requirements promulgated by safety and regulatory agencies such as Underwriters Laboratories, the United Nations and various European safety agencies.
  • Train your store personnel to familiarize them with these procedures.
  • Do not offer to service cheap e-bikes purchased from unscrupulous Internet distributors.  Substandard lithium-ion e-bike battery packs are much more likely to fail than those supplied by quality vendors.
  • Do not buy no-name battery packs to replace packs that have reached the end of their service life.  Given the high cost of replacement packs, it’s tempting to buy a cheaper pack to make your customer happy.  But there is a reason quality replacement packs are expensive. They are safer.  Procure replacement packs from the distributor that sold you the e-bike in the first place.
  • Follow the safety guidelines offered by the lithium-ion battery pack recycling firms that are opening.  Companies like Call2Recycle will offer guidance and materials to ensure that you safely store and transport used battery packs at the end of their useful service life to an accredited recycling facility.

In closing, please know that the chances of a lithium-ion battery fire in an e-bike shop are miniscule. But the consequences of a battery fire are so significant that the relatively simple steps outlined in this advisory are more than justified.

About us: Human Powered Solutions, LLC, (HPS) exists to support individuals and businesses in the bicycle industry wanting to participate in the micromobility revolution currently underway in the world. We strive to offer advice and counsel related to commercial opportunities, product development, sourcing, distribution, and retail activities in the micromobility space. Our skill set entails expertise and experience in both the commercial and the technology sides of these industries. Please do not hesitate to contact us if you have any questions regarding the recommendations outlined above.

Mike Fritz
Chief Technology Officer
mike@humanpoweredsolutions.com

Disclaimer:  You assume all responsibility and risk for the use of the safety resources available on or through these guidelines. Human Powered Solutions, LLC (HPS) does not assume any liability for the materials, information and opinions provided on, or available through these guidelines. No advice or information given by HPS shall create any warranty. Reliance on such advice, information or the content of these guidelines is solely at your own risk, including without limitation any safety guidelines, resources or precautions related to the development or installation of battery storage and charging stations, battery storage and battery charging protocols, or emergency procedures, or any other information related to safety that may be available on or through these guidelines. HPS disclaims any liability for injury, death or damages resulting from the use thereof.

Vandalism aside, Battery Fires Simply Don’t Have to Happen!

Providers in the Micromobility supply-chain, including bike shops and self-service rental companies need to be proactive in making sure lithium ion battery fires simply don’t happen – because they are preventable! 

Vandalism is a possibility at any time and is a criminal act that needs to be deterred and prosecuted, but actual lithium battery fires are a very real possibility that only happen if professional policy and procedures aren’t followed. 

Let’s start by making it very clear that all lithium ion batteries have the potential to be volatile – like gasoline in an automobile gas tank, or other combustibles sitting in your garage, shop, or warehouse.  There is a lot of energy stored in a lithium ion battery pack, which is why they are well suited for light electric vehicles.  But when that energy is released in an uncontrolled fashion, bad things can and do happen.

But until the battery industry develops fire-proof lithium batteries, there are a number of steps that we, as importers and distributors of electric bikes, can do to minimize the possibility that a battery fire will occur involving the products that we represent.  Those steps involve informed battery pack specification setting, and careful, well thought out sourcing.

There are usually two separate entities involved in the production of a lithium ion battery pack intended for use in a LEV:  the cell producer and the pack assembler. 

Cell producers manufacture the cells that store the energy.  Household names like Sony, Samsung, LG and Panasonic are among the most well-known.  They have factories dedicated to the process of fabricating the lithium ion cells used in applications like ours.

Battery packs are usually assembled by a third-party.  Pack assemblers purchase the lithium cells from the battery manufacturer per the customer’s specifications.  They test and sort cells based on minute differences in cell capacity.  They design and source battery pack housings based on customer requirements.  They spot-weld the nickel bus bars that interconnect the cells to create the required voltage and capacity attributes of the pack.  Very importantly, the pack manufacturers source, install and program the battery management system (BMS) into the battery pack.

I believe that lithium battery fires occur, in the absence of blatant misuse or abuse, due to deficiencies that are introduced during the cell manufacturing process.  Therefore, it is of the utmost importance that cells specified for your battery pack are sourced from a vendor that utilizes manufacturing methods and quality control procedures of the highest caliber. 

Equally important is the utilization of a high-quality BMS.  The BMS is a microprocessor based on-board electronic device that ensures that the battery pack is always used and maintained within the well-established, mandatory service limitations dictated by the cell manufacturer.  But there’s more to the BMS than quality electronics.  The BMS must be programmed with operating and control parameters that are closely matched to the electrical attributes unique to your particular vehicle.

By carefully specifying and sourcing lithium battery packs for LEV usage, we can go a long way to ensuring that these remarkable energy storage devices are safe and reliable, and perfectly suited for use in our nascent industry.

Mike Fritz

Chief Technology Officer

Human Powered Solutions, LLC