Preventing E-Bike Battery Fires
This post was updated to correct some technical information. Thank you to PeopleForBikes for providing additional information about lithium batteries and safety certifications.
E-bikes aren’t inherently dangerous on the road and may even be safer in some situations if the electric boost allows a rider to escape a dangerous traffic situation. Much of the current e-bike safety panic is thinly disguised bikelash. However, there is one e-bike safety concern that does have some basis in reality: battery fires.
The lithium batteries that power e-bikes (and electric cars, scooters, computers, and other devices) pack a lot of power into a relatively small space. These batteries allow e-bike riders to go 30 to 50 or more miles on a single charge. However, lithium batteries burn at high heat if they catch fire, presenting a potential hazard when riders charge their bikes inside homes or garages.
Fortunately, there are several things you can do to safely charge your e-bike battery.
Don’t leave the battery unattended while charging
Your e-bike is very unlikely to burst into flames while you’re riding; most documented e-bike battery fires have happened during charging. When a lithium e-bike battery gets plugged in to charge, it can get overheated if the membranes separating the individual battery cells are too thin.
Don’t leave your battery plugged in overnight, and keep an eye on it while it’s charging. If it starts to get hot, unplug it immediately and take it outside of your home.
Buy a bike with a safety-tested battery
The bicycle industry advocacy group PeopleForBikes suggests buying a bike with a battery that meets UL 2849 or EN 15194 standard. The UL certification means that an independent laboratory has tested the drive system and battery to a voluntary US safety standard published by Underwriters Laboratories. The EN standard is an EU certification, and the two safety tests are very similar; either can give you peace of mind that your battery has well-constructed lithium cells and a battery management system (BMS) designed to prevent conditions like overheating, overcharging, or a short circuit that can lead to fires.
The only downside of these higher-quality batteries is that they’re expensive, adding to the price of the bike and the battery replacement cost. However, the safety tradeoff is worth it.
Don’t use aftermarket batteries or accessories
Many e-bike battery fires have been linked to aftermarket batteries. In New York City, where e-bike delivery workers can travel 100 miles or more in a day, some use batteries designed to hold a longer charge that lack the proper separation between lithium cells or lack a BMS. Poorly designed batteries can overheat during charging, which may lead to fires.
If you need to replace your e-bike battery, buy the battery designed for the motor on your bike.
Extension cords have also been linked to battery fires. Always plug your battery charger directly into an outlet.
Protect your battery from the elements
When e-bike batteries get damaged, they’re more susceptible to catching fire. Don’t use a battery pack with a damaged case. To keep your battery healthy, protect it from the elements and extreme temperatures as much as possible.
How the California E-Bike Incentive Program could improve e-bike safety
In addition to a general movement across the country to ensure the safety of e-bike batteries, California’s E-Bike Incentive Program, which will launch soon, could have a positive impact on battery safety. The program, which will provide millions of dollars of incentives to help low-income Californians purchase e-bikes, mandates that eligible models must have safety-tested batteries. That could motivate manufacturers to focus more on battery safety and retailers to gravitate toward e-bikes with batteries that have been proven to be safe. CalBike applauds the California Air Resources Board for making this standard one of the elements of the program.
The greatest e-bike safety threat remains poorly designed streets
While lithium battery safety is important, it’s not the biggest safety threat for people who use e-bikes for transportation or recreation. Most of the e-bike-related fires in the US have occurred in New York City, but many more people have been killed by traffic violence while riding e-bikes. Over half the e-bike crashes nationwide during the study period of a recent NTSB report occurred in the five boroughs of New York City.
California has, fortunately, seen relatively few fires caused by improper e-bike charging or overheated batteries. But traffic violence poses a real and ongoing threat to people on all types of bikes and CalBike is committed to working toward safer streets for all vulnerable road users.
