SF Moves to Ban Uncertified Lithium-Ion Batteries

San Francisco District 5 Supervisor Bilal Mahmood introduced legislation Tuesday that would ban the sale of uncertified lithium-ion batteries within city limits, partnering with the SF Fire Department to push through rules that officials say are long overdue.

The legislation would restrict local and online retailers to selling only lithium-ion batteries carrying a UL Solutions certification label, which signals the product meets established safety standards. Beyond sales restrictions, the measure gives teeth to enforcement: the fire chief could fine residents up to $1,000 for possessing non-certified batteries, and the city attorney could pursue legal action against merchants caught selling them, whether they operate on a storefront or through an online platform.

The push comes after 120 lithium-ion battery-related incidents occurred in San Francisco between 2024 and 2025, according to Mahmood’s office, with dozens of those taking place in or near the Tenderloin. A fire last December in that neighborhood displaced 45 residents, and SF Fire Department data shows structure fires linked to uncertified batteries have been climbing steadily for several years. Dense residential corridors, where a single unit’s battery fire can rapidly spread to dozens of neighbors, have absorbed a disproportionate share of that risk.

“This measure is intended to prevent dangerous and fast-moving fires before they start, particularly in dense residential buildings where a single battery failure can threaten dozens of residents,” Mahmood said at Tuesday’s Board of Supervisors meeting.

Fire Chief Dean Crispen spelled out the specific danger. “Non-UL batteries can be charged over their expected limit where it causes thermal runaway, which creates a large amount of fire and smoke which is toxic to the members of our community as well as the members of our fire department,” Crispen said. Fire Lt. Mariano Elias added that battery fires typically ignite with almost no warning, starting with a small amount of smoke before escalating to sparks, a large explosion, and a release of toxic fumes. Elias also noted these fires are exceptionally difficult to extinguish once they fully ignite.

Most batteries sold through mainstream U.S. retailers already carry UL Solutions certification, which means the legislation primarily targets a narrower but dangerous segment of the market. Experts have pointed to some budget e-bike models as a category where uncertified batteries occasionally slip through. Mahmood was careful to separate the device from the battery itself.

“The problem here is not e-bikes and scooters, the problem is when people are using non-UL certified batteries in them,” he said.

That distinction matters for enforcement. The legislation is structured around the battery, not the vehicle or device it powers. That approach makes it easier to apply the rules broadly, since lithium-ion batteries show up in phones, laptops, and cordless vacuums just as much as they show up in e-bikes. Any of those devices, paired with a non-certified battery, carries the same thermal runaway risk that firefighters have been responding to with growing frequency.

Mahmood framed the legislation as a basic alignment between city law and technological reality. “Our laws need to catch up with our technology, and this is the first step to do so,” he said.

The equity dimension here is hard to miss. Budget-priced e-bikes and cheaper electronic accessories often attract buyers in lower-income neighborhoods, where residents may not know that a lower price tag sometimes reflects corners cut on battery safety. The Tenderloin, one of the city’s most economically distressed neighborhoods, has already absorbed a disproportionate number of these incidents. A policy that pulls non-certified batteries off shelves citywide could provide the most material benefit to residents who have the least cushion to absorb a catastrophic loss.

Whether the legislation passes and whether enforcement holds up in practice are questions that will play out at the Board of Supervisors over the coming weeks. But the coalition behind it, a supervisor with a track record on tech policy and a fire department bringing data and operational credibility, gives the proposal a stronger foundation than most.

For now, Mahmood’s office has at least put the number on the table: 120 incidents in roughly two years is not a trend a city can wait out.