The recent catastrophic fire at the Coeur d’Alene (Idaho) Police Department’s storage building, determined to be caused by an e-bike battery, has sparked continuing concerns about the safety of lithium-ion batteries used in e-bikes. Fire pattern analysis led fire investigators from the Idaho State Fire Marshal’s Office and the Coeur d’Alene Fire Department to focus on recently acquired battery-operated e-bicycles, one of which clearly showed evidence of a catastrophic failure in the lithium-ion battery pack that was being charged after being used that evening by the police.
This article aims to educate rather than deter agencies from utilizing the proven effectiveness of e-bikes. While quality, well-maintained e-bike batteries are safe, they do carry a small risk of catastrophic failure.
Understanding e-bike lithium-ion batteries
High-capacity lithium-ion batteries are widely used in e-bikes (normally 500 watt hours and more) due to their high-energy density and long life. Like gasoline, lithium-ion battery packs must be properly used and maintained.
All high-capacity e-bike lithium-ion batteries require the use of a Battery Management System (BMS). Without a BMS, failure is inevitable! Even with a BMS, thermal runaway can occur — especially if the battery is not properly cared for, charged and stored. It is one of the primary risks related to lithium-ion batteries. It is a phenomenon where a lithium-ion cell (battery packs contain up to 60 individual cells) enters an uncontrollable, self-heating state.
Thermal runaway can result in:
- Ejection of gas, shrapnel, and/or particulates (violent cell venting)
- Extremely high temperatures
- Smoke
- Fire
Purchasing, storing and maintaining e-bike lithum-ion batteries
Here are key considerations for purchasing, storing and maintaining e-bike lithium-ion batteries to ensure safety and longevity.
1. Look for UL 2849 and 2271 Standards when purchasing duty e-bikes
Before purchasing duty e-bikes from a reputable manufacturer that are preferably designed and built to meet the specific needs of your agency, it is crucial to ensure they meet UL Standards.
- UL 2849 Standard: This covers the e-bike’s electrical drive train system, battery system and charger system combinations.
- UL 2271 Standard: This specifically covers batteries and their chargers. A battery pack will not comply with the performance and safety requirements of UL 2271 without a “protective circuit” or battery management system.
Recognizing the necessity and importance of UL Standards, the State of New York recently enacted lithium-ion battery safety legislation. For additional information on UL Standards, click here.
Ensure you request a current UL Standards “Certificate of Compliance” from the dealer or manufacturer of your e-bike, as these certificates are typically valid for only 12 months. Additionally, you can check for a UL certified sticker on the outside of the battery.
2. Charging practices
Here are suggested best practices:
- Use only UL-approved chargers supplied by the e-bike manufacturer. Do not use generic chargers or power supplies.
- Avoid charging batteries unattended (at all times of the day). Unplug the charger as soon as the battery is fully charged to prevent overcharging. If constant monitoring is not possible, the use of a mechanical timer is acceptable — but not ideal — to ensure power to the charger will shut off at a designed time.
- Only use direct wall outlets. Avoid using extension cords or power strips, which can cause overheating.
- Avoid full discharge as this will prolong the life of the battery.
- Charge batteries out of direct sunlight, in a well-ventilated and dry area ideally at room temperature (around 68°F or 20°C). Ensure the location is free of trash, cardboard, paint, or any other flammable materials, and close to a fire/smoke detection system. with a fire sprinkler system if possible. This applies to the storage environment as well.
- Always refer to and follow the owner’s manual for additional recommendations.
3. Storage practices
Like bicycle shops, law enforcement agencies may house a varying number of e-bikes. It is crucial to understand how to safely store the bikes’ batteries when they are not in use.
- Purchase a fire-resistant cabinet, or better a specific lithium-ion battery cabinet with flame arresting vents as seen here from CellBlock. CellBlock cabinets are designed to charge battery packs within. The cabinet is designed to contain a single pack failure in a protected “cubby.” In fact, CellBlock integrates 110v outlets in the cubby to facilitate charging. CellBlock has other options as well.
- Ensure the cabinet is large enough to store all e-bike batteries. Store all e-bike batteries in the cabinet until needed. Do not charge batteries inside non-lithium-ion specific cabinets.
- Avoid storing batteries long-term when they are fully charged or completely discharged. Instead, aim to store them at a charge level between 30%-60%, with 30% being ideal. Keep in mind that the higher the charge percentage, the more energy the battery contains.
- Always refer to and follow the owner’s manual for additional recommendations.
4. Regular inspections
Regardless of whether batteries are in use or in long-term storage, they must undergo regular inspections for signs of damage, such as cracks, dents, or swelling. If you notice any issues or if a battery is accidentally dropped, refrain from using it again. Instead, promptly take it to an authorized e-bike dealer for inspection. Regular inspections must cover the following:
- User: In addition to pre-ride inspections (ABC”E” Quick Check – E for Electronics: on-board display/computer, ride/assist mode switch, motor, battery, speed sensor, and its magnet), bike officers must examine the battery for any signs of damage, such as cracks, dents, or swelling.
- Local bike shop: As part of your e-bike’s regular maintenance program, ensure that your local bike shop inspects the drive unit system (motor and battery) for performance and any signs of damage as noted above. Always rely on an authorized service dealer specific to your brand’s drive unit system.
5. Include e-bike batteries in your agency’s fire safety plan
It is critical your agency include its e-bike fleet in its fire safety plan. Details should include, but not be limited to:
- Where the e-bikes are stored.
- The number of e-bikes and extra batteries.
- The capacities of batteries in watt hours (Wh).
- Mitigation measures in place (fire/smoke detection system, fire sprinkler system, etc.).
- Emergency notification and evacuation measures. Important: In addition to fire risks, lithium-ion batteries emit highly toxic smoke! Do not attempt to be a hero — evacuate the building immediately!
Invite your local fire department to visit and inspect where your fleet of e-bikes is stored. This is an excellent opportunity to ask questions and seek their recommendations, including the need for additional training for bike officers and other relevant personnel, as well as procedures to follow before and during a thermal runaway event. Unfortunately, FDNY has extensive experience with lithium-ion battery fires and can provide valuable insights.
6. Importance of proper training and policy
As emphasized in my Police1 article on police e-bike training and operational considerations, training is essential regardless of the make, model, or type of e-bike your agency uses. Trainers and agencies deploying personnel on e-bikes must incorporate the latest best practices for e-bike lithium-ion battery safety into their training prog.rams, and policies and procedures.
For additional information on lithium-ion battery safety, visit Safe Lithium-Ion Battery Storage and Charging Procedures for the eBike Shop – Human Powered Solutions. HPS representatives would be more than happy to answer any questions you might have.
Conclusion
By incorporating these tips, you can enhance the safety and lifespan of your e-bike lithium-ion batteries. Proper care, charging, storage, training practices and policy are crucial to prevent fire incidents and ensure the ongoing availability of your electric bicycle fleet. However, it is crucial to recognize that even high-quality battery packs with UL Standards certifications are not infallible or completely safe.
One final word on lithium-ion batteries. Because they are considered hazmat waste, they must be properly disposed of (not in your recycling bin). Linked here is a nationally recognized program to safely and responsibly dispose of your old batteries.
Disclaimer: While I am not a subject matter expert on e-Bike lithium-ion batteries, I have consulted with various cycling industry experts for this article. I would like to extend my gratitude to representatives from HPS and the Home - National Bicycle Dealers Association (nbda.com) for their valuable assistance. You assume all responsibility and risk for using the safety resources provided in these tips. I do not assume any liability for the materials, information, and opinions available through these tips. No advice or information given by me shall create any warranty. Reliance on such advice, information, or the content of these tips is solely at your own risk, including any safety tips, resources, or precautions related to the development or installation of battery storage and charging stations, battery storage and charging protocols, emergency procedures, or any other safety-related information. I disclaim any liability for injury, death, or damages resulting from their use.
