This is the first time I've seen/heard over-discharge mentioned in relation to lithium battery fires:

QUOTE: RNSW investigators believe the fire was related to a compromised lithium-ion battery that immediately went into thermal runaway.

Thermal runaway is a process where a lithium-ion cell overheats and gives off toxic gases before exploding into flames.

Principal research scientist at CSIRO, Dr Adam Best, said thermal runaway can happen in two ways.

"It can occur due to either overcharge, so a charger continues to pour energy into a battery after it has reached its full state of charge, causing the battery to break down and, with that, causing significant heat," he said.

"That can lead to all the materials inside the battery breaking down and creating a fire. In most instances, it can be uncontrolled."

He said a similar event can happen through a process called over-discharge.

"That's when you actually discharge too far and the battery goes into a reverse-polarity and can also go through a thermal breakdown and runaway."

Lithium and cobalt go together like Condy's crystals and glycerine. Why companies keep making them is just baffling. Whilst the energy density is better than lithium iron and other chemistries, the safety factor needs to be addressed.

Lithium cobalt batteries in mobile phones spontaneously combust without warning, and for no apparent reason, and often do so whilst they are in the user's pocket. Thousands of people around the world have been badly burned because of it.

I think we have two deaths being attributed to lithium type batteries. This could be related to the claim made by a US university, that fast charging causes the dielectric to crack and metal dendrites to form.

That would lead to an internal short.

I don't think there is a single battery chemistry that likes being fast charged. At best it'll simply shorten the battery's life. At worst, it'll be as you described. The battery will go bang. It's like a pie eating contest - one of the participants will always succumb to the contest's demands and chuck up what he just ate. The rest will just feel a bit off colour. None will like what they just did.

I have sundry laptops, torches, powertools, phones, earbuds and headphones that have Li cells in them. These all present a fire risk. But how to mitigate it? They all take many hours to charge and it isn't practical to supervise them 24/7. So what is the solution short of making a special charging location out of fireproof materials outside of the house. I could do this having a yard. But for people in appartments this may not be an option.

Presently I charge my battery drill batteries with a timer set at the advertised charging time because the charger has no control circuitry linked to the battery. Can see where it should go though by looking at the plug and socket arrangement of the batteries and charger.

But that is the only mitigation presently being used.

Presently I charge my battery drill batteries with a timer set at the advertised charging time because the charger has no control circuitry linked to the battery

Ditto. I have two non-digital HPM 'D812COUNT4' 4 hour countdown timers for such purposes. (I gave up on digital timers long ago after they either failed or died in a power surge, and there's no putzing around with menus).

I also use the old motor driven timers because you know where you are with them. I found the electronic timers too easy to get the settings wrong - doesn't matter so much with Christmas lights, but not for battery charging.

Talk of timers reminds me when I used 24 hour event timers to start and stop pumps and generating sets.
They were the motor driven tick tock dial types that had a 24 hour dial that you pushed coloured pegs into holes in the dial to define the running time.
So simple, even the most challenged person could work out if you pushed a green peg into 6 oclock the pump starts and a red peg into 12 oclock stops the pump.
They came in 240 volt and 12 volts volt versions and were just so simple to use.
Used then for years until................

Enter programable electronic units that came with a 12 page manual showing you how to set them up and with grand promises of accuracy, leap year, summer time, daylight saving, day omit, Sunday run program ( as if the cows would know the difference) and God knows what else. All of this via a keypad so small that an average farmer's thumb would push all the buttons in one go!

I explained to the supplier that all a soldier/farmer/milkman/ordinary person needs is a pump or generator to start up at ABOUT 600 and run to ABOUT 2200 every day until doomsday and that is ALL that is needed.
But this was the time when local manufacturers were being shut down by tariff rule changes and computers were coming in and we all know computers are so much better than the old tick tock inaccurate things don't we?

I used a few of the new whiz bang programmable timers and go so much flack then imported a whole batch of tick tock timers to cover production until we had to close down being beaten by a flood of imported cheap gear but that's another story..

Fred.

QUOTE: Lithium-ion battery-related fires are "becoming an epidemic", according to Fire and Rescue NSW (FRNSW), after responding to two more blazes in Sydney this morning

One of the things I still do with battery charging with the higher rate chargers, is still use an adjustable timer. One estimates, or knows how long the battery will take to charge, & little bit more if its one of those regulated chargers that cut out, or goes to float.

So once that time has elapsed the timer kills the circuit.

Apparently the charger on the latest one was modified. A home made no break here, with some age on it actually has a barretter. If the battery is dead flat, or drops a cell, there is no way that it can overload the transformer charging it.

As I may have mentioned? Recently I had a SLA acid battery explode in service in the Ute. Generator current & voltage were normal at the time it went bang. LEL in the engine bay in the moving vehicle would not be a factor.

Incredible!

QUOTE: [Fire and Rescue New South Wales] has recorded more than 60 lithium-ion battery fires in the state so far in 2024, which have injured seven people.

There were more than 270 lithium-ion battery-related fires in 2023, or more than five a week.

Re the ABC article of GTC's, it advises

"Don't leave them in your bedroom or inside the house if possible, and only use accredited charges and batteries."

There are two phones in my household that are charged in the bedroom, as I guess the majority are especially if you have a busy lifestyle. So presumeably these are reasonably safe though the article doesn't say.

I have three ALDI torches that have Li cells (about 10, 5 and one years old) and these have eliminated expensive 6V dolpin torch size batteries going flat from being left on - no good as these are needed emergencies and blackouts. The ALDI torches have had their problems - the newest one burnt out the main beam LED and also its switch (a three position push button) wore out. The LED was replaced and the switch replaced with a slide switch from junk box. The slide switch is more convenient and the new LED is brighter. The ALDi torches are overall a success, though another I got a refund for when the battery stopped taking a charge, luckily just short of the warranty period.

These torches have no no battery management system (BMS) as Ian mentions in Post # 15 - just a red LED that comes on, but charging continues. Why not replace the LED with a cut-out. Extra components and cost I suppose. This is where regulation should step in, to insist on a BMS, or at least a charge cut-out.

The only charger that gets used in the house, is that for the Mobile phone & that is not often. If it is, its in the kitchen sitting in something which dissipates heat (curved) and can handle heat if it decides to melt down.

For the 6 & 12V Batteries that tend to sit the tractor has a small solar panel with fuse; while the rest of the common use ones for floating are automatic & under an amp. That in a battery like a ZZ70 type (12" long 7"deep &7" wide) would not notice that thermally. The only one of them that has exploded, was the Utes whilst being driven (C39 generator).

Highest charge rate charger is one of those apparently smart 7 stage automatic things 7A. If the SLA lead acid is 10V as they usually drop a cell. I will not jump start the vehicle. They tend to end up bunded & in the other vehicle that's going to get the replacement.

On automotive. The nacelle in my car uses Nicola Tesla's idea for charging the phone. This I consider intrinsically unsafe as its an impatient fast charger. That makes the phone seriously hot, to the point where I consider it, on a long trip to be a fire hazard and I do wonder if these things are contributing to car fires?

I think the biggest time bomb of all is the fact that modern homes have garages built into the front of them so the blocks can be made smaller. On the classic Aussie 1/4 acre block (~1,000 square metres) there is plenty of room for a detached garage but not these days with the average block being around 650 square metres. If an electric car decides to commit suicide in an attached garage there will be problems because there are no fire-rated walls or doors between the garage and the living areas. Smoke often kills occupants in house fires before the flames do and electric cars aren't short on it when they go up.

At what point will insurers refuse a claim on a fire started by lithium batteries?

They seem to be good at weaseling out of paying up