San Diego Fire/Rescue Facebook

“Burning ithium-ion batteries emit smoke that is exceedingly toxic."

The rise in popularity of e-bikes around San Diego County has grown so much over the past couple of years that it seems more commonplace to find cyclists utilizing them on the local roads than their traditional, non-electric counterparts. A recent report on eBikes.org finds that 15 percent of the US population now owns at least one e-bike, while 11 percent of city dwellers own at least one e-bike with an additional 17 percent planning to purchase one within a year. Since 2020, e-bikes have even accounted for more imports than their electric automobile counterparts. In short, the popularity of e-bikes is exploding, and they are here to stay.

Now the bad news — they utilize lithium-ion batteries that are gaining a reputation as being prone to catching on fire. Earlier this year an East Village high rise had to be evacuated when a charging e-scooter caught on fire. The building’s sprinkler system extinguished the fire, but that resulted in $150,000 in water damage to units in the building. 

In April 2023, an e-bike battery explosion in a Barrio Logan apartment building resulted in serious injuries for one resident, while a charging e-bike battery was suspected to have sparked a fire in the garage of a Serra Mesa condominium in July 2023 resulting in an estimated $50,000 in damages. 

Even though it wasn’t e-bike related, the difficulty of extinguishing a large-scale fire involving multiple lithium-ion batteries was on full display during a blaze at an Otay Mesa energy storage facility in May. That fire smoldered for weeks and required a 600-foot safety barrier to prevent civilians from exposing themselves to high levels of hydrogen.  

San Diego Fire-Rescue Department public information officer Monica Munoz cites aftermarket lithium-ion batteries as often being the main culprit in electric bike and scooters fires. “People buy these after-market batteries that come from a variety of different countries,” she explains, “but the regulation when it comes to the manufacturing and the safety measures that are built into the battery don’t exist in other countries. So, here in the United States, the phones we use and the other devices we use have to be certified and they have to go through testing. Lithium-ion batteries have devices inside that when they are finished charging they will stop. They don’t just keep cooking. But, in other countries, when the batteries are made, they skip those safety steps.”

“When lithium-ion batteries, or any batteries for that matter, burn it’s called thermal runaway,” she adds. “They emit smoke that is exceedingly toxic. The best thing is for people not to have to smell it or be close to it because of its toxicity. So, it’s not only dangerous to have a fire, but it’s also very dangerous to have a fire of lithium-ion batteries where you are in the room with it. 

"Often what you will see in some of these safety videos that you might find online is that people will try to pick up whatever it is and take it outside. Really, the best thing for you to do is get your family members and pets and just get out. If it’s a little tiny phone or charger like an exterior charger for an added battery for a phone or something like that and you can throw it outside that’s one thing, but for a micro-mobility device where you would actually have to lift it up — I wouldn’t take a chance on that.”

As San Diego’s downtown and mid-city populations increase in density it’s also important to remember not to charge micro-mobility devices in a space such as a doorway in a small apartment. “On the FDNY page you will see a bunch of examples of fires in peoples’ residences and they can’t get out because they block the doorway with whatever the micro-mobility device is,” she explains. “Often, they don’t have a lot of space in their apartments. So, that’s one of our main safety recommendations — don’t ever charge a device that’s in front of a doorway or some type of entrance or exit.” 

If you do choose to utilize an after-market battery for a micro-mobility device, she stresses the importance of keeping an eye on it while it is charging. “Don’t put them in your garage and let them charge forever because that’s a very common fire as well. People put things in their garage, or they keep their e-bikes in the garage. In San Diego that makes sense to us, but if you’re not monitoring the device when it's charging then you’re not gonna know or you might not be home.”

“Part of what NFPA [National Fire Protection Association] recommends is that people don’t leave devices charging overnight in garages or in places where you can’t monitor them,” she adds. “For example, if I’m charging my bike during the day and I’m around my house and I smell smoke, I can act immediately. I can call 911 and I can get out. If you leave it charging overnight, it adds a little bit of extra time because it may be cooking really well before you smell the smoke or before your smoke detector goes off. So, we just want to buy the most amount of time possible for people.”