A forensic investigator is examining whether lithium-ion batteries caused the fire that has shut down CapMetro’s Bikeshare system since Memorial Day weekend.

Nearly 500 electric bikes, used as many as 40,000 times a month, have been pulled from at least 76 docking stations peppered around UT, downtown, East Austin and neighborhoods south of downtown.

CapMetro has provided no estimate for when Bikeshare service could be restored.

The blaze broke out on the night of May 23 at a CapMetro facility located on Ben White Boulevard at Judson Road, east of Burleson Road. Almost 40 Austin firefighters responded.

At first, the building was too hot and smoky to enter, according to radio communications obtained by KUT News. Firefighters forced open rollup doors to ventilate the building and pushed in, looking for the source of the fire.

Minutes later, they found it: a battery charging room.

“We believe it’s batteries. They’re popping off,” a firefighter inside the building radioed to his colleagues outside.

In a fire incident report obtained through the Texas Public Information Act, one firefighter described the room as “full of batteries, most of which were probably e-bike batteries.”

Firefighters cooled the batteries enough to load them into bins, rolled them outside and submerged them in water.

The Ben White fire is not being investigated as arson, according to the Austin Fire Department. But CapMetro has hired Rimkus, a forensic engineering firm with expertise in lithium-ion battery fires, to determine the cause.

CapMetro officials won’t say whether they believe the fire was sparked by batteries, but they’re not ruling it out.

“It’s somewhat unclear,” said Art Jackson, CapMetro’s vice president of demand response. “That’s why we wanted an independent third party to come in and look at what happened and give us some answers.”

Jackson said CapMetro wants those answers before restoring service, but couldn’t say how long the investigation might take.

“The safety and well-being of our customers and the community is our first priority,” he said. “We don’t think that there’s a significant safety issue, but we don’t know.”

A bike catches fire on South Congress

About four hours before the fire at CapMetro’s Ben White facility, a Bikeshare bike started smoking while docked outside Jo’s Coffee on South Congress Avenue.

South Austin resident Tag Brown pulled up in his car as it was happening.

“The sky was just filled with white smoke. It was almost ACL headliner level of smoke coverage,” Brown said. “One of the bikes was docked in the station, and it was just smoking profusely.”

Brown said it was a busy Saturday evening on South Congress. Firefighters arrived and sprayed the bike with water.

“The smoke itself was putrid and just had a sulfuric scent to it. You get a little bit and you’re just like, ‘I need to move away from this immediately,'” he said.

CapMetro’s Jackson confirmed the South Congress Bikeshare fire was a “battery incident” that is also being investigated by Rimkus.

Why one battery room mattered so much

The Bikeshare shutdown has exposed one of the biggest challenges behind Austin’s transition to electric bikes: Most of the docking stations can’t charge them.

Austin’s bikeshare network started in 2013 with 80 unpowered bikes under the brand B-Cycle. As the system grew, electric-assist bikes were added, which give riders a boost while pedaling. Those bikes quickly became more popular, especially in Austin’s heat.

“It’s been very clear to us that e-assist bikes are what people prefer,” then-CapMetro executive Chad Ballentine told City Council members in 2022. “Those are used three to five times more often than the human-powered, manual-powered bikes.”

That’s when they decided to go all-electric. It took a couple years, but in 2024, CapMetro awarded a $20.6 million, 10-year contract to the Montreal-area company PBSC Urban Solutions, which is owned by the ridesharing giant Lyft.

CapMetro and the city are close partners on the bikeshare program. CapMetro operates and maintains the technology and hardware. But the city owns it all, partly because more grant funding is available to cities. In 2024, the Texas Department of Transportation gave Austin $11.3 million in federal funds for the transition to e-bikes.

One of the biggest challenges of Bikeshare and similar systems across the United States is connecting docking stations to the electrical grid. Getting permits and installing conduit is time-consuming and expensive.

So far, only a dozen Bikeshare stations — fewer than 1 in 5 — are electrified. The South Congress dock where a bike caught fire does not offer charging.

So workers had to swap out depleted batteries from bikes in the field, drive them to the Ben White facility and plug them into chargers. That made the battery room at the facility a critical part of the system.

Battery swapping is common in electric bikesharing systems. A recent operations research paper described the labor-intensive practice as the dominant way such systems keep batteries charged, and said the work can account for about 35% of operating costs.

CapMetro’s own budget documents show the agency has been trying to expand charging infrastructure. In 2025, CapMetro ordered 10 electrified Bikeshare stations with integrated charging. In 2026, CapMetro plans to install 20 more.

What investigators have to determine

For now, the Bikeshare docks are empty across Austin. How soon they’ll be filled with electric bikes again depends, at least in in part, on what investigators find inside the burned-out battery room that kept the system running.

University of Texas professor D. K. Ezekoye, who studies battery safety and fire forensics, said lithium-ion batteries are generally safe. But when failures happen, they can be intense.

“When a single cell fails, it goes to very high temperatures, hundreds of degrees up to, say, 2,000 degrees Fahrenheit or so,” Ezekoye said. “Then it spews out toxic and flammable gasses.”

But Ezekoye cautioned that the presence of burned batteries doesn’t prove they started the fire. He’s seen arson cases in which criminals placed batteries to try and make a fire look accidental.

“This is where it gets complicated,” he said. “Trying to identify whether the battery was the cause of the fire or itself was attacked by the fire a subject of intense research.”

CapMetro has not provided a damage estimate except to say there was “extensive” destruction of the batteries and chargers. The transit agency says it has insurance and is working with the city of Austin on a “fiscally responsible” approach to replacing the system.

Lyft did not respond to requests for comment.