Compact, powerful and increasingly ubiquitous, lithium ion batteries are among the most common causes of apartment fires in San Francisco. A new bill proposed by Supervisor Bilal Mahmood would regulate their sale in the city after a massive conflagration in the Tenderloin displaced 45 people in December.
The proposal, which Mahmood planned to introduce at the Board of Supervisors meeting Tuesday afternoon, would ban the sale of devices, primarily scooters and e-bikes, using batteries that do not meet certain safety standards. Retailers that sell products with unregulated batteries to city residents would be subject to fines of up to $1,000 by the San Francisco Fire Department.
Chief Dean Crispen of the fire department explained that batteries that are not tested and certified by Universal Laboratories can overheat during charging, potentially causing explosive fires that spread extremely quickly. By the time firefighters arrive to respond, Crispen said, battery fires can spread outside an apartment unit into hallways and air wells.
“It really puts us at a disadvantage,” he said.
Mahmood hopes the measure will help address the root cause of dangerous battery fires like the one that ripped through the top floors of 50 Golden Gate Avenue in December. Some residents, many of whom were low income or older, feared they would become homeless after the city deemed the building unsafe.
The Tenderloin, where that fire took place, is the “epicenter” of these kinds of events, Crispen said, because the neighborhood is so densely populated and many of the buildings are old and lack sprinkler systems.
The neighborhood is also home to lots of affordable housing, Mahmood said, which can increase the stakes for people who are displaced.
Batteries were also responsible for two separate fires outside of the Tenderloin last week alone: one at the Seneca Hotel in San Francisco that landed one person in the hospital and another in San Jose that turned deadly when a man collapsed outside, likely from smoke inhalation.
“We’ve had loss of life, we’ve had injury, it’s a huge problem in the city,” Crispen said.
Mahmood has been personally acquainted with the problems the batteries pose since before he even took office: a Tenderloin apartment building he lived in caught fire on two occasions around 2024 because of faulty lithium ion batteries. Both times the damage was contained and Mahmood was able to keep living there, he said.
Between 2021 and 2025, lithium ion batteries caused more than 120 fires in San Francisco. The numbers keep going up, Crispen said.
Mahmood’s proposal builds on 2024 restrictions limiting households to four lithium-ion powered “personal mobility devices,” like scooters, each and mandating that devices must be plugged directly into outlets, not power strips, for charging. That year, there were 24 battery fires, according to Crispen. The next year, there were 36.
“It was clear that we needed more legislation to get to this at its heart,” Mahmood said.