Dramatic videos and phone footage of a fire in a Toronto subway car…after an e-bike and its battery ignited is raising further questions about the safety of lithium-ion batteries.
From Nick Westoll and Michelle Mackey, CityNews (link)
What are the inherent fire risks with electric vehicles?
Lithium-ion battery chemistry can become unstable over time leading to a condition called “thermal runaway.” Damage to the battery case from an impact, or using an incorrect charger can lead to spontaneous fires that start very quickly, burn hot and are nearly impossible to extinguish.
When it comes to the frequency of vehicle fires, the record for electric vehicles is currently very good. Most EVs are less than five years old, and fires attributable to battery ageing are still many years into the future. (Consider that the average vehicle will be 15 years old when it is scrapped, and that one in five vehicles is still on the road after 20 years.) The wild card is impact damage, either from hitting debris on the road at speed, or a T-bone type collision that damages the battery case and starts a fire.
The automakers are much more responsive about recalling EVs that catch fire than they are for their gasoline models. For example, Hyundai USA recalled three model years of the Kona EV after 15 reports of battery fires, yet looked the other way while thousands of gasoline models caught fire due to defective four-cylinder engines.
To date, most Lithium-ion battery fires have come from small mobile devices (view the CityNews report). With e-bikes or scooters, you may hear a hissing or popping noise. Get away quickly – there is no time to put the fire out using conventional means nor to wheel away the device.
Typically, you will see a dark cloud comprised of metal particles, and then a large cloud of what looks like steam. It’s not water vapour – the cloud may contain hydrochloric acid. It burns, is dangerous to inhale and carries a risk of catching fire or explosion.
For small appliances the CityNews report mentions fire fighters burying a burned-out battery pack in sand to ensure it doesn’t re-ignite. For larger fires like auto batteries, it takes A LOT of water to cool the battery module. The challenge: the top of a battery pack is shielded by the floor of the vehicle and underneath it is shielded against road debris. According to one expert, extinguishing an EV fire with water from a hose is “Like trying to put out a fire on your stove by spraying the roof of your house.”
EV battery safety tips
A mandatory safety standard and more robust product recall system should probably be mandatory for small devices. Look for a CSA or UL rating on the battery pack. The automakers have developed their own safety solutions for the much larger battery modules in electric vehicles. Here are some tips for e-bikes and scooters:
- If you’re aware of a developing malfunction with your battery pack, stop charging the batteries.
- Don’t store your device for extended periods with a 100% charge. That can stress the batteries.
- Use the appropriate charger matched to the battery pack. Consider the original battery pack and its charger and circuitry to be a single system.
- Don’t modify or “boost” performance from a battery module.
- In the event of visible damage to the case, consider replacing the battery pack.
- Don’t park a scooter or e-bike in front of exits or blocking stairwells. You’re very unlikely to be able to move it out of the way if it starts to burn. Ideally, charge or park outside.
For now, the track record for EV auto batteries can be considered good but incomplete. EV batteries are manufactured to high standards and have more failsafes than personal transportation devices, but vehicle battery modules are much larger and store far more energy than the batteries in e-bikes and scooters. The APA looks forward to the day when Lithium-ion chemistry will be superseded by a more stable battery chemistry.
For a deep dive into Lithium-ion battery design and fire risks, watch this video from expert Paul Christensen