How to avoid E-bike battery fires and explosions

Although there are no national or international statistics on how often the lithium-ion batteries commonly found in e-bikes or scooters catch fire, these incidents “seem to be happening with some regularity – and the numbers are rising.” , according to the National Fire Protection Association.

In New York, for example, the city has seen a dramatic increase in battery-related fires in recent years, with incidents skyrocketing from 30 in 2019 to 220 in 2022, according to the New York City Fire Department. Of last year’s fires, six ended in fatalities.

“Once the fire starts, everything in the battery burns,” said KM Abraham, a lithium-ion battery expert and former professor at Northeastern University.

But Abraham and other experts emphasize that batteries from reputable manufacturers that have undergone testing and certification are generally considered safe. They say problems can arise when batteries are damaged, modified, or made inferiorly. Here’s what you should know about these batteries and how you can reduce the risk of fire and explosion.

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What are lithium ion batteries and how do they work?

These powerful rechargeable batteries can be found in everything from cell phones and laptops to electric vehicles.

“Lithium-ion batteries have this incredible performance advantage over other types of batteries because they can store a lot of energy and they can store it for a long time,” said Benjamin Preston, an auto reporter at Consumer Reports and a volunteer firefighter.

They consist of single or multiple lithium-ion cells and a protective circuit board. The cells consist of a negative electrode and a positive electrode separated by a thin porous barrier known as a separator, which allows lithium ions to move from side to side through a liquid or gel that conducts ionic current . The movement of lithium ions from the negative to the positive electrode within the cell and electrons through the external load creates the electrical current that gives the battery its juice to power devices.

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What could cause a fire or explosion?

Lithium-ion batteries contain a large amount of energy stored in a small volume, and many of their components can be flammable. They have complex chemistry and structure, so there are multiple ways they could catch fire and potentially explode, said Anna Stefanopoulou, a professor of mechanical engineering at the University of Michigan who studies batteries.

Physical damage such as impact from an accident, misuse or defects, or other manufacturing issues could lead to short circuits or other failures that cause the energy in the battery to be released “out of control,” Abraham said.

If one of the cells shorts out, it could generate electrical currents 20 to 50 times higher than what the battery is designed for, Stefanopoulou said. This could set off a chain reaction of cells heating up, causing a rapid rise in pressure and temperature inside the battery.

“Even in a small battery, that temperature can go as high as 1,500 degrees Fahrenheit,” Abraham said.

As the cells heat up, they create combustible gases and high pressure inside the cell, Abraham said. At that high pressure, he noted, the gases can rupture the cell container and be released, burning on contact with air or with just a spark.

Why are these battery failures so dangerous?

Lithium-ion battery fires or explosions are particularly dangerous because they can be sudden and spread aggressively.

A cell phone battery that catches fire and explodes can generate enough force to blow out a car window, Preston said. Larger batteries, like those used in e-bikes and scooters, can do “significant damage” to spaces and have even been known to tear down walls, he said.

“It’s crazy how fast this goes,” he said.

In addition, batteries “have been known to reignite unexpectedly (without warning) minutes, hours, and even days after all visible fires have been extinguished,” according to the New York City Fire Department.

Water and fire extinguishers also do not work on these fires. In fact, submerging a battery in water could make things worse, Abraham said, since water reacting with lithium can create hydrogen, a highly flammable gas.

How can I reduce the risk of these incidents?

Last month, New York City Mayor Eric Adams (D) signed into law a bill on e-bike safety, but similar regulations are still nascent in the United States. In the meantime, experts recommend taking the following steps to reduce the chances of a battery fire or battery explosion:

Think about what you buy. Avoid buying batteries or chargers that are not recommended by the manufacturer. Experts suggest making sure your battery meets safety standards by looking for certifications. In the United States, Underwriter Laboratories or UL certification is a widely accepted standard. However, note that some products may incorrectly advertise these certifications.

Pay attention to charging. The Consumer Product Safety Commission recommends using the charger that came with your device and following the manufacturer’s instructions. Try not to leave your e-bike unattended while charging – e.g. B. if you plugged it in overnight while you slept – and unplug it once it’s fully charged.

Also think about where you park and charge your e-bike. “You don’t want a scooter or an e-bike in your bedroom or in an entry hallway” where it might block an exit, Preston said.

In addition to keeping bicycles away from flammable materials, do not leave items near external heat sources such as radiators or space heaters. Stefanopoulou added that bikes should be charged outside in the shade whenever possible.

Take care of your battery. If you crash or otherwise damage your bike, make sure you check your battery, Stefanopoulou said.

“Every time you fall you check your head and your arms and your knees and everything, I think you should check yours too [battery] pack,” she said.