How to tell whether your lithium batteries are a fire risk — and what to do if they are
Damaged, worn-out batteries can cause a fire, so experts say to watch for warning signs
We've heard a lot about how dangerous hot, fast-moving lithium battery fires are and their rising number — more than 1,500 in communities across Canada last year.
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fires → tell → Canada
But most of us also keep and charge smartphones, power banks, e-bikes, vacuum cleaners, drills and lots of other lithium battery devices at home without any issues.
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most → keep → issues
Can batteries really go from safe to risky?
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batteries → go → risky
And what should you be doing about this?
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Experts generally agree that overall, lithium batteries are very safe.
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batteries → agree → ?
Vinny Gupta, assistant professor of fire safety engineering at the University of Waterloo, notes that more than 10 billion battery cells are now manufactured every year.
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cells → note → Waterloo
"And we typically only hear about safety issues in just a few of them.
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"
The problem is when the systems fail and they do catch fire, it's "quite dramatic," acknowledged Gupta, who does research that involves intentionally making them fail and catch fire to study their fire risk.
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them → fail → risk
Safety measures typically built into consumer lithium batteries include temperature sensors, pressure relief valves to vent potentially flammable gases and systems to prevent overcharging.
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measures → build → overcharging
So do you really need to take measures like watching them as they charge and unplugging them as soon as they're done charging, as firefighters advise?
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firefighters → need → them
It's true that the battery should automatically stop charging.
But experts note that a battery that has been safe all along can become a fire risk at some point.
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that → stop → point
How can a lithium battery that was safe become a fire risk?
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that → become → ?
David Giles, CEO of TempAlert, a Halifax company that sells heat-sensing battery-monitoring stickers, said even if people are using batteries as intended, they can become damaged and therefore hazardous.
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they → sell → batteries
He says that when you drop your phone, you may notice if you crack the screen.
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you → say → screen
"But you also may have done other internal damage that might not show up right away" — including damaging the battery.
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that → do → battery
TempAlert makes heat-sensitive stickers that change from black to yellow at 60 C, indicating a problem with your battery.
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that → make → battery
Heat, such as from charging your battery in the sun, can also cause damage.
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Heat → charge → damage
Gupta said one of the most common ways to cause a battery to fail is by overcharging it.
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battery → say → it
Typically, batteries are designed to prevent that, but some are more poorly designed than others, and the risk increases if they're tampered with or paired with the wrong charger.
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they → design → charger
Giles says that's easy to do, since most have connectors that fit into many devices.
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that → say → devices
But he warns they may be designed for different voltages.
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they → warn → voltages
The wrong charger "could be ramming, you know, 80, 90 volts into a battery only designed for 40.
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you → ram → 40
That's when you start having a major problem."
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you → start → problem
Repeatedly charging and recharging a battery over time can also eventually cause it to wear out and fail.
When that happens, does the battery catch on fire right away?
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battery → charge → fire
"Batteries don't just go into thermal runaway instantly," Giles said.
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Giles → go → runaway
Thermal runaway is a term for when a battery starts to rapidly self-heat, generating more heat and creating a feedback loop that can lead to a fire.
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that → start → fire
"It progressively gets worse and worse."
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Lithium batteries are found in many devices, including e-bikes, and most are safe.
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most → find → bikes
When a battery first starts failing, it may feel hot to touch while charging — Gupta says that's "the earliest indication" that something is wrong.
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something → start → ?
At that point, it will usually cool when you unplug it.
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you → cool → it
Giles said that may happen repeatedly before it stays hot even after being unplugged.
So how much time do you really have before you have a dangerous fire?
"To be honest, we don't really know," Gupta said, as it depends on what is going on inside the battery and the self-heating process is exponential once underway.
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process → say → battery
Giles said it could take days or weeks of charging and use, or it could take just 20 minutes.
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it → say → minutes
The two most popular lithium battery chemistries are NMC (nickel manganese cobalt) and LFP (lithium iron phosphate), which have different materials in their cathodes.
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which → have → cathodes
Several readers wrote in to suggest that LFP is less combustible and prone to overheating.
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LFP → write → overheating
But in Gupta's opinion, "It's hard to really say if one chemistry is safer than [the] other … there are trade-offs."
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chemistry → say → other
It's true that LFP is less energy dense and goes into thermal runaway at a higher temperature (about 235 C, compared with 200 C for NMC).
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LFP → go → NMC
It also ejects fewer solid fragments of battery when overheated — but more gas, Gupta said: "And that gas is often laden with both toxic and flammable products.
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gas → eject → products
So, how do you stay safe?
Buy batteries with Canadian safety certifications such as CSA, cUL, cETL on the charger.
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you → stay → charger
Make sure you use the correct charger with your battery, even if another one fits in the charging port.
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one → make → port
These are the kinds of certification marks you should look for on your battery charger, according to the Government of Canada lithium-ion battery safety website.
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you → look → website
…and 16 more, not listed.
The Aporia
