Battery Fire Risks

[IanA]

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.

Phil, Pleased to hear you have both fire blankets and extinguishers at home and at work. A few years ago I was in the workshop when the plumber came in shouting 'Quick have you got a fire extinguisher?' Once outside I saw a plume of smoke a hundred feet high coming out the house roof. The one thing I did not have, and had never needed anything more in my entire life, was a fire extinguisher! (Accepting one day there might be things I would need more, for example a torniquet) Hearing the fire sirens approaching was a transcendental experience and the Edinburgh firemen/women were amazing to see doing their job. Today the house and workshop are full of extinguishers and I even give them away as Christmas presents to relatives and friends. The Scottish Fire Service recommendations re extinguishers certainly don't recommend not using them. So if you don't have an extinguisher, I say go and get one today before you need it more than you ever needed anything else in your life.
Cheers
Ian

 

[isaac3d2]

+1 for "err on the side of caution".

1) I buy good quality batteries not cheap stuff from China or India where safety standards are ... er let's be polite.... rubbish. (over the last year or two, I've moved to DeWalt for my cordless tools not least because the batteries should be more reliable)
2) I try to remember to not leave large batteries charging overnight.
3) I try to remember to remove batteries from tools when not in use.
4) Storing charged batteries in a metal bin would be my next safety upgrade.

In the end, I'll probably never have a battery fire, but I'd rather keep that chance as low as possible.

 

[Phil Pascoe]

https://simplyextinguishers.co.uk/

May or may not be the cheapest, but they price inc. P&P and genuinely have next day delivery. They're very efficient and worthy of a plug.

 

[ColinDeVelen]

Speaking as a Li Ion battery engineer for a popular power tools company I can only say the following. A Li Ion battery will catch fire if it gets too hot and goes in to 'thermal runaway'. It is this that causes the pack to burn through each cell. The first cell to burn heats the next couple, which burn and heat the next couple and so on.
This is usually caused by either a partial short circuit condition in the tool/charger, or by a partial short circuit condition inside the pack (dropped in a puddle and then shaken out as an example.) Now, each individual cell has some built in safety features, and each pack also has some safety features. Modern power tools also contain safety features as well. The upshot of this is that the tool/charger will be communicating with the battery pack, and the two together will also help to reduce the likelihood of a fire. The conditions required to get a battery pack to go in to thermal runaway are fairly specific, so the chances of a thermal event are very low.
To answer the OP's original questions.
Yes, I have seen power tool packs catch fire, but then, evaluating the risk of this is part of the test work we do. We try to actively make this happen so that we can improve the design.
I personally store packs on tools, or separately. I also leave packs on chargers overnight.
Good design helps to reduce risk in all battery use scenarios.

 

[PhilTilson]

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.

Absolutely not the case! Far and away the biggest cause of lithium battery fires is over/bad charging. Yes, a shorted battery may well catch fire, but not very likely in the circumstances described.

 

[Richard_C]

In Cambridgeshire we have had a recent fatal house fire attributed to an electric bike charging overnight, and a couple of bin lorry fires where it seems like the crusher has crushed and shorted a battery pack, created a hot spot and got the rest of the rubbish burning. In those cases the fire brigade raked out the contents onto the road and extinguished - vehicles were OK (ish).

It strikes me that the batteries are fine as long as they don't get a sudden discharge or an inappropriately high charge rate both of which cause them to overheat very quickly. I always charge my power tool batteries while I am around, never unattended, the terminals are well shielded anyway, so beyond that I don't see the need for any special precautions. Millions are in use, the ones that don't catch fire never get in the news.

The problem has been around for a long time. The 2013 Boeing 787 fires are interesting, seems like internal shorting in a cell was the root cause, or maybe the battey, being inanimate, didn't read the no smoking signs on the plane.

https://en.wikipedia.org/wiki/2013_Boeing_787_Dreamliner_grounding


(I know some posters are keen to start a car (ev vs petrol) debate but that's not what this is about.)

 

[MikeH]

Never had a problem with a power tool battery, BUTTT....

We were once taking some button batteries out of a keychain torch, so that shows how small they were. They had been in a drawer for some time so probably not in the best condition. As I tipped them onto the tabletop, so no real chance of a short, one of them just exploded in a rather spectacular manner, firing pieces of battery case all over the kitchen. It was a massive crack and flash of light. No harm done but we both had to go and change our underwear!

 

[John Brown]

There must be millions of people charging their phones every day. How often do you read of a phone catching on fire ?
My guess is that cheap eScooters and the like are the problem. When I was working, I was happy to design and program charging circuits for nickel based battery packs, but insisted on bought-in charging components for Lithium.

 

[dannyr]

There must be millions of people charging their phones every day. How often do you read of a phone catching on fire ?
My guess is that cheap eScooters and the like are the problem. When I was working, I was happy to design and program charging circuits for nickel based battery packs, but insisted on bought-in charging components for Lithium.

they certainly did have a prob with fire several years ago, but not much now - shows how this can be sorted with attention

 

[John Brown]

Never had a problem with a power tool battery, BUTTT....

We were once taking some button batteries out of a keychain torch, so that shows how small they were. They had been in a drawer for some time so probably not in the best condition. As I tipped them onto the tabletop, so no real chance of a short, one of them just exploded in a rather spectacular manner, firing pieces of battery case all over the kitchen. It was a massive crack and flash of light. No harm done but we both had to go and change our underwear!

What chemistry were the button cells? The ones I've seen in keychain torches were not lithium.

 

[GuitardoctorW7]

Absolutely not the case! Far and away the biggest cause of lithium battery fires is over/bad charging. Yes, a shorted battery may well catch fire, but not very likely in the circumstances described.

Decent device manufacturers use intelligent charging systems. The number of scare stories I get from Apple haters about devices blowing up is, in 99% of cases, people using cheap Chinese knock off chargers and leads. To Apple's credit if there is any sort of problems there's usually a recall and free repair/replacement (up to 6 years in the UK)
Ooops sorry just kicked off a sharpening thread

 

[John Brown]

Decent device manufacturers use intelligent charging systems. The number of scare stories I get from Apple haters about devices blowing up is, in 99% of cases, people using cheap Chinese knock off chargers and leads. To Apple's credit if there is any sort of problems there's usually a recall and free repair/replacement (up to 6 years in the UK)
Ooops sorry just kicked off a sharpening thread

Surely Apple devices have the actual charging intelligence in the device, the thing you plug in is just a glorified power supply, same as with EV " chargers"? I can see the cheap Chinese knock-off(although I suspect the genuine Apple accessories are from China) catching fire or failing, but the laptop or smartphone should be relatively safe, shouldn't it?

 

[MikeH]

What chemistry were the button cells? The ones I've seen in keychain torches were not lithium.

No idea John, it was in so many pieces it would be impossible to tell. I am pretty sure it was what came with the torch, so probably fairly cheap.

 

[Agent_zed]

Surely Apple devices have the actual charging intelligence in the device, the thing you plug in is just a glorified power supply, same as with EV " chargers"? I can see the cheap Chinese knock-off(although I suspect the genuine Apple accessories are from China) catching fire or failing, but the laptop or smartphone should be relatively safe, shouldn't it?

The fires I've seen reported from mobile phone charging was not the battery starting the fire but the actual charger itself. I've seen a video of the cheap chargers being opened up and examined to show cheap components that are positioned badly that allow for overheating and shorts in the charger itself.

 

[John Brown]

The fires I've seen reported from mobile phone charging was not the battery starting the fire but the actual charger itself. I've seen a video of the cheap chargers being opened up and examined to show cheap components that are positioned badly that allow for overheating and shorts in the charger itself.

Agreed. My American relations bring USB "chargers" barely bigger than a sugar cube. They claim to work at 240v, but it's hard to imagine they conform to whatever the physical isolation distance between mains and low voltage is. I keep a couple of IKEA 3 output units on hand, and forbid the use of the hot sugar cubes.

 

[John Brown]

The fires I've seen reported from mobile phone charging was not the battery starting the fire but the actual charger itself. I've seen a video of the cheap chargers being opened up and examined to show cheap components that are positioned badly that allow for overheating and shorts in the charger itself.

Except, as I said previously, they're not chargers, just 5v power supplies.

 

[MikeJhn]

The main reason for battery fires is user abuse, one of the worst things a user can do is to continuing to use the battery after it has indicated, by low power or switching off, that is needs charging, this will eventually lead to the lowest charged cell going reverse polarity, leading to adjacent cells overheating with the inevitable results, during the advent LiPo batteries this was a common occurrence in the model aircraft hobby, lots of sheds, garages and even homes lost, cheap chargers and cells have not improved this.

 

[yngndrw]

In the remote-control model vehicle scene, we often use high-capacity lithium batteries and in some spaces (Such as FPV drones), these often get physically damaged from crashes. These batteries are not protected during discharge and get a beating, although fancy chargers are usually used which do re-balance them.

The majority of people in the hobby will use some form of protection during charging, storage and transport. A common tool is the Bat Safe charging box, which is essentially an insulated steel container which is designed to prevent flames from escaping while still allowing a controlled release of the gasses/smoke.

They are a bit expensive so some people just make a little concrete "charging bunker" outside from paving slabs and concrete blocks.