Lithium-ion battery fires - what you need to do to stay safe

10 November, 2022 By: Ruth Callaghan

Such destruction remains rare, but WA firefighters warn the incidence of battery fires is climbing, as more and more household goods become battery charged.

Found in everything from mobile phones to vacuum cleaners, e-cigarettes to electric drills, lithium-ion (or li-ion) batteries are a critical component of almost all rechargeable appliances.

On the one hand, the batteries make it possible to enjoy many of the conveniences we take for granted — like working on a laptop, riding in an electric wheelchair, or zipping to work on an e-scooter. On the other, li-ion batteries pose a serious risk to people and property if they catch fire.

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High energy stored in lithium-ion batteries

Because they are packed with cells that store significant energy, if one becomes damaged or overheats, it can trigger a chain reaction known as a thermal runaway, where temperatures can reach 500 degrees Celsius.

The battery can explode, setting alight furniture or fabric, potentially destroying a home or office in a matter of minutes. And yet, warns Peter Jones, a District Officer at WA’s Department of Fire and Emergency Services (DFES), most people don’t take the threat of battery fires seriously.

“It doesn’t seem to make any sense to people as a threat because a battery seems so ordinary,” says Jones, who works in the Department’s Fire Investigation and Analysis area.

“You don’t have any of the normal things that might make you perceive it as a threat and nothing that would suggest it is a potential fire cause at all. But it is a massive energy source.”

Battery-related fires are increasing

That lack of awareness means people tend to be less cautious than they should be when charging or storing li-ion batteries and the results can be catastrophic.

In the past five years, the number of structure fires in WA believed to have been caused by battery fires has doubled, with 59 incidents in 2021/22, representing one in every 20 structure fires. And unlike more common causes of fire, where householders might intervene early or call emergency services, many battery fires go unnoticed until it is far too late.

“We used to go to a house fire, and somebody would have left a candle on or an electric blanket going, or a chip pan had caught fire,” Jones says.

“The person would have done something that caused the fire to start, or they would see something or smell the smoke.

“But we’re attending fires now where nobody has done anything at all, other than plugging something in six hours earlier to charge, or they just brought a new product into the house. We’re also seeing more fires that start when nobody is home so there is no one for the smoke detector to warn.”

If a cell within a battery fails or short circuits, it can overheat and catch fire, creating a dramatic and dangerous chain reaction.

“Once it starts that chemical process, you can’t extinguish it because it is in a sealed unit,” Jones says. “You can’t put water inside a battery unit. When it starts to break down, or you start to see white smoke coming out, it is starting to undergo thermal runaway and it will continue to escalate. The cells can then explode and fly five or 10 metres, with a mass of burning fragments.”

What happens next can depend on where the battery was in the home. Jones says battery-operated tools left on a charger for too long in a garage could easily overheat but as few garages include a smoke detector, the fire can go unnoticed.

“Of course, that’s where all your camping gear is, your petrol, your car, your paint,” he says.

“If I throw an exploded battery five metres in any direction in your garage it is going to hit something that will catch fire, so don’t recharge your batteries in there.”

Inside the home, a battery blaze can quickly spread to furnishings or curtains. Even if the fire is contained to one or two rooms, the destruction adds up.

“As these batteries are powering an ever growing array of devices and appliances, we have seen an increase in claims related to their use,” says RAC Insurance Claims Manager Glen Walker.

“We recently had a claim in excess of $1 million for a Perth home destroyed due to e-bikes being charged, and also a number of fires where power tools have been left charging.”

What causes a lithium-ion battery to fail?

The common thread is that some kind of damage has happened to the battery — even if it is invisible to the human eye.

Li-ion batteries are highly efficient and have high energy density, so they can deliver large amounts of current for longer than most competing batteries. But they also tend to overheat, so need to be designed with safety measures to reduce their volatility.

To reduce the risk of fire, batteries and their recharging devices need to pass stringent safety tests to be sold in Australia. Despite this, incidents happen.

Jones says firefighters have seen fires caused by new batteries and old, some on charge and some that appear to have been disconnected from power when the fire broke out.

DFES has also seen fires that may have been triggered by second-hand or nonoriginal chargers that failed to prevent a battery overheating while on charge.

“Let’s say it is a cordless vacuum cleaner — perhaps it has been losing power on a regular basis which might show the battery is degrading,” he says. “Or sometimes the charger and the battery are no longer talking to each other, so the battery is fully charged but the charger doesn’t recognise it and doesn’t turn off.

“We’ve seen poorly manufactured batteries or those that have just overheated because they are in direct sun through a window. You might have a battery that has physical damage, where it has been mechanically ruptured. There can be a range of different reasons.”

Even disused batteries can pose a risk. Jones says there are regular fires in rubbish trucks believed to have been caused by old batteries crushed in the machinery.

“You can understand that someone gets lazy and instead of dropping the battery into the right kind of recycling, they throw it in the bin. But if the battery goes into the rubbish truck and the machinery squashes the laptop or power tool or whatever it might be, the truck could catch fire. You have to think of these things like an unexploded bomb.”

How to reduce the risk

In the meantime, there are simple steps that householders can take to reduce the chance of fire — starting with awareness of the risks.

Peter Jones recommends against charging batteries on soft surfaces like beds or couches and keeping them away from flammable goods.

The location used for charging should also be assessed for risk. Peter recommends rooms like bathrooms or laundries where the risk of a fire spreading is relatively low.

It may also be wise to avoid second-hand battery-operated products that may have been damaged in the past. Damaged batteries or batteries that are not charging properly should be appropriately disposed of. At the very least, if the battery has any visible damage, then it’s time to go. You should also stick to buying only reputable, branded battery chargers.

Most importantly, Jones says, never overcharge.

“Take the battery off charge when you’re not home, and if the red light turns green unplug the charger,” he says.

“When it’s done it’s done. You can’t get any more charge in, and if you try you’re just adding to your risk.”