Battery Fire Risks

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Established Member
11 Oct 2018
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Lausanne CH and Suffolk UK
I have been working in my daughter's flat where space is at a premium and she has stored a number of my cordless tools in their boxes underneath her bed.

I am sure we have all seen reports of e-bikes and e-cars catching fire and their batteries increasing the intensity of the fire - and this got me thinking about the risks of a power tool battery fire - especially in such a vulnerable location.

I have removed the batteries from everything under her bed, but what do others do?

Do you store batteries separately / outside / in some cabinet?

Has anyone actually seen a tool battery catch fire (I haven't)?

Is the risk on items like e-bikes greater due to lower manufacturing standards than power tools?

Is the risk over-hyped given so many things nowadays are cordless and have batteries (I notice her vacuum cleaner has - when she is not using mine)?

I would invite other's thoughts
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I had a battery for my Nikon DSLR explode. It didn't cause much damage, but melted part of the charger.

I think the risk is far greater when charging, so I try not to leave bikes / tools on charge when I'm I'm not in the same room, but I probably wouldn't remove them when not in use.
You made me think! A bit of googling and the level of actual incidents is very low, although growing. The majority seem to be from large battery devices, scooters, ebikes etc and most of them during charging. Many fire services provide similar guidance to avoid scenarios where:
  • Batteries charged with incompatible equipment or overcharged following completion.
  • Multiple batteries charged at one time, overloading the circuit, or users not allowing the battery to cool properly beforehand.
  • Improper storage of batteries, such as in hot and unventilated environments, or in proximity to flammable liquids.
  • Using cheap or unregulated batteries that haven’t passed specific safety tests.
  • Manufacturing defects or external damage to the battery.
I have a battery charger in my shed that I leave batteries installed in, I think this is a practice I will stop. Otherwise seems no more risky than other household electrical risks, shorts/overheating.

I think this is a problem when the device is some unknown import, cheap E-Scooters and such more than cordless batteries on powertools from the known brands. Buying non OEM batteries is an issue as they have had some serious problems because they are cheap for a reason, charging is often when these issues show up because the charging is often crude without controls in place to monitor battery temperature that can result in thermal runaway. A much bigger problem is the disposal of all Lithium batteries where they are all a major issue because if damaged they can combust in spectactular fashion that is more colorful than the Northern lights and dangerous.
If you think about it you probably have a load of things with lithium batteries in them that you don't worry about. E.g Electric toothbrush, Electric razor, Digital cameras, vacuums (as you mentioned), Mobile phones, some alarm clocks (mine is for example), Bluetooth speakers, kids remote control cars etc etc.

I also keep 2 hitachi drills on a shelf in my kitchen.

As mentioned above, my understanding is that they are only likely to catch fire whilst charging or perhaps if they are damaged e.g causing a short.

I only charge in the daytime though just to be slightly safer and only when I'm in.

I looked into making a battery pack recently and the important bit is some form of protection on the cells. The protection circuit prevents overcharging of the cells which could lead to a fire etc.

I see a lot of really sketchy looking battery packs on deliveroo type riders bikes. They have clearly bodged them up. that would scare me. But items bought from respectable companies just sitting around I personally wouldn't worry.

Probably worth mentioning is having good working fire alarms whatever you do, as even good electronics can develop faults.
I have quite a few battery tools and when they have needed replacing over the years, they are all pretty much now Li Ion......(Still got a couple of 20 year old Bosch NiCad battery tools that still take a charge!....)

Personally, I've never had any issues with batteries self combusting but a mate of mine ( in the same line of work as me) had a fire occur in his van about 18months ago and the firemen reckoned that it was caused by a short across one of the Li Ion batteries in one of his tool cases.......He reckoned he had left a few loose screws rattling around in there and one of them had managed to short across the Live & Neutral of his spare battery.

I've got into the habit now of never leaving charging batteries unattended,....certainly I would never leave a battery & charger on overnight!!
Food for thought here, I'm just going to fit a smoke alarm in my workshop. Always charge batteries in the middle of the concrete floor just in case, never seen one catch fire.
I've never read of of a battery on a charger catching fire - the fires always seen to be a short of a bare battery.

I think since the advent and more common use of Li Ion batteries, it has become apparent that the batteries can potentially be an issue by catching fire.....Wasn't there a ban by airlines refusing to carry Li Ion batteries in their cargo holds....? I think it was after a few airplanes caught fire and the batteries were suspected to be the culprit......I thought I remembered reading it somewhere...?
I have fire extinguishers, fire alarms and fire blankets in the kitchen, the lounge (+CO), the garage and the new shed. I did read, though that the fire services now advise against extinguishersand fire blankets .................. as they encourage people to have a go.
as they encourage people to have a go.
What happened to the "only tackle a fire if it is safe to do so" message. You have to apply a little common sense and not just don't bother and watch a house or shed burn down. Tacking a lithium fire might be pointless though because it still burns when smothered and total submersion seems to be the way the fire services tackle them.
I've had an old bosch battery expand/split in the back of my radio/charger. It didn't catch fire though.
I've never read of of a battery on a charger catching fire - the fires always seen to be a short of a bare battery.
You may be refering to drill batteries specifically but Li batteries in general its well known that charging creates a risk. all the advice from various agencies state that charging is a risk.

This is just one example from a google search:
'In Merseyside in January, Rab Shearer and his son Gary were killed when an e-bike battery set to charge overnight caused a house fire.'

Article lists numerous incidents of charging related fires.

It would seem unlikely to me that a battery that is charged and just sitting in a drill etc would just short and catch fire. It would need some reason to begin the reaction.
we certainly need to up battery safety re fire risk, but just imagine having a tank full of highly combustible fluid in your bike/tool/car.

my car was written off recently because a diesel Range-Rover parked next to it and burst into flame (electrical fault most likely) (no, not Luton airport where the same thing happened) and yesterday I saw a high powered m'bike in flames (luckily no-one hurt) - never seen a chainsaw, petrol-mower or leaf blower burn but a friend council worker said disaster was narrowly averted in their stores a few years ago.

batteries must be made safer (apple/iphone seem to have done it after bad publicity) but I think this should be do-able

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