There has been conjecture here about lithium battery ignition, thermal
runaway, and whether any measurements could provide useful warning of
a possible cell explosion.

Waiting for my biscuits to cook, a (very) little research turns up not
much about failure dynamics. Most studies measure external cell
temperature as indicators of thermal runaway.

I found one study, from NREL, that used fast radiography to study the
propagation of a reaction front from a local defect.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi0lbm44PWBAxXRIkQIHWNyAsQQFnoECCoQAQ&url=https%3A%2F%2Fwww.nrel.gov%2Fdocs%2Ffy22osti%2F82410.pdf&usg=AOvVaw3CJ_O8Y-D-J8zDUulMU_mT&opi=89978449

or

https://tinyurl.com/yn9r2rzh

The separators between reactants are usually thin polymers and the
thermal conductivities are low, so I'd expect a small defect to spread
rapidly, somewhere between burning paper and burning gunpowder, I'd
guess.

The NREL radiography shows reaction propagation velocity in the
ballpark of 20 mm/s, so a cell with a small central defect could be
fully engaged in a second or so. Not much time to detect and mitigate
a failure.

This study does conclude that many other gross-measurement studies are
probably unreliable.

On Sat, 14 Oct 2023 08:20:22 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Saturday, October 14, 2023 at 11:08:53?AM UTC-4, John Larkin wrote:
>> There has been conjecture here about lithium battery ignition, thermal
>> runaway, and whether any measurements could provide useful warning of
>> a possible cell explosion.
>>
>> Waiting for my biscuits to cook, a (very) little research turns up not
>> much about failure dynamics. Most studies measure external cell
>> temperature as indicators of thermal runaway.
>>
>> I found one study, from NREL, that used fast radiography to study the
>> propagation of a reaction front from a local defect.
>>
>> https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi0lbm44PWBAxXRIkQIHWNyAsQQFnoECCoQAQ&url=https%3A%2F%2Fwww.nrel.gov%2Fdocs%2Ffy22osti%2F82410.pdf&usg=AOvVaw3CJ_O8Y-D-J8zDUulMU_mT&opi=89978449
>>
>> or
>>
>> https://tinyurl.com/yn9r2rzh
>>
>>
>> The separators between reactants are usually thin polymers and the
>> thermal conductivities are low, so I'd expect a small defect to spread
>> rapidly, somewhere between burning paper and burning gunpowder, I'd
>> guess.
>>
>> The NREL radiography shows reaction propagation velocity in the
>> ballpark of 20 mm/s, so a cell with a small central defect could be
>> fully engaged in a second or so. Not much time to detect and mitigate
>> a failure.
>>
>> This study does conclude that many other gross-measurement studies are
>> probably unreliable.
>
>
>Supposedly the solid electrolyte batteries eliminate that hazard. Then there are others using electrode materials that do not combust on contact.

If there are enough joules stored in the reactants of a battery to
pump it up 1000c or so, it's going to be hard to keep them apart.

Liquid flow batteries are a great concept. Most of the energy is
stored as two separated tanks and only a little has to get close and
react.

On Sunday, October 15, 2023 at 4:18:13 PM UTC+11, Eddy Lee wrote:
> On Saturday, October 14, 2023 at 9:59:11 PM UTC-7, Anthony William Sloman wrote:
> > On Sunday, October 15, 2023 at 2:08:53 AM UTC+11, John Larkin wrote:

<snip>

> > > The separators between reactants are usually thin polymers and the thermal conductivities are low, so I'd expect a small defect to spread rapidly, somewhere between burning paper and burning gunpowder, I'd guess.
>
> Ejecting over 50% of the mass in couple of minutes would qualify as firework/rocket, in my humble opinion.

You wouldn't do well in the pyrotechnics industry.

> > But what's going to produce that "small defect"? If it was there at manufacture the battery would burn up when it was first charged.
>
> > > The NREL radiography shows reaction propagation velocity in the ballpark of 20 mm/s, so a cell with a small central defect could be fully engaged in a second or so. Not much time to detect and mitigate a failure.
> > But such a defect would wreck the battery on first use. A working cell hasn't got such a defect.And they don't seen to develop them all that often - if at all.
>
> Not necessary, I have many cells going bad after several charge/discharge cycles. They would get hot enough to be problematic, if not with the fuse for disconnection.

If you overcharge them enough to develop lithium metal bridges inside the battery, leading to high self-discharge and cell heating, you can produce a problem.

Modern battery management systems are designed to minimise that risk, but you seem to bypass them.

> > > This study does conclude that many other gross-measurement studies are probably unreliable.
> >
> > So somebody should fund more of their studies, which they imagine to be more reliable.
>
> We don't need a Ph.D, to know that Lithium cells can ignite.

Flyguy is equally convinced of the same proposition. If he had the skills to get a Ph.D. he might also have the sense to realise that you (or a couple of properly programmed integrated circuits) can manage lithium cells in a way that makes them much less likely to ignite.

--
Bill Sloman, Sydney

On 15/10/2023 3:03 am, John Larkin wrote:
> On Sat, 14 Oct 2023 08:20:22 -0700 (PDT), Fred Bloggs
> <bloggs.fredbloggs.fred@gmail.com> wrote:
>> On Saturday, October 14, 2023 at 11:08:53?AM UTC-4, John Larkin wrote:

<snip>

> If there are enough joules stored in the reactants of a battery to pump it up 1000c or so, it's going to be hard to keep them apart.

There are a whole lot of utility scale grid storage batteries that have
lasted for years, so it isn't all that difficult.
> Liquid flow batteries are a great concept. Most of the energy is
> stored as two separated tanks and only a little has to get close and
> react.

It's a great concept, but it hasn't been attractive enough to get
anybody to manufacture them in mass market quantities at mass market prices.

Tesla has eaten their lunch.

--
Bill Sloman, Sydney

On Sat, 14 Oct 2023 22:18:09 -0700 (PDT), Eddy Lee
<eddy711lee@gmail.com> wrote:

>On Saturday, October 14, 2023 at 9:59:11?PM UTC-7, Anthony William Sloman wrote:
>> On Sunday, October 15, 2023 at 2:08:53?AM UTC+11, John Larkin wrote:
>> > There has been conjecture here about lithium battery ignition, thermal
>> > runaway, and whether any measurements could provide useful warning of
>> > a possible cell explosion.
>> >
>> > Waiting for my biscuits to cook, a (very) little research turns up not
>> > much about failure dynamics. Most studies measure external cell
>> > temperature as indicators of thermal runaway.
>> >
>> > I found one study, from NREL, that used fast radiography to study the
>> > propagation of a reaction front from a local defect.
>> >
>> > https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi0lbm44PWBAxXRIkQIHWNyAsQQFnoECCoQAQ&url=https%3A%2F%2Fwww.nrel.gov%2Fdocs%2Ffy22osti%2F82410.pdf&usg=AOvVaw3CJ_O8Y-D-J8zDUulMU_mT&opi=89978449
>> >
>> > or
>> >
>> > https://tinyurl.com/yn9r2rzh
>> >
>> > The separators between reactants are usually thin polymers and the thermal conductivities are low, so I'd expect a small defect to spread rapidly, somewhere between burning paper and burning gunpowder, I'd guess.
>
>Ejecting over 50% of the mass in couple of minutes would qualify as firework/rocket, in my humble opinion.
>
>> But what's going to produce that "small defect"? If it was there at manufacture the battery would burn up when it was first charged.
>> > The NREL radiography shows reaction propagation velocity in the ballpark of 20 mm/s, so a cell with a small central defect could be fully engaged in a second or so. Not much time to detect and mitigate a failure.
>> But such a defect would wreck the battery on first use. A working cell hasn't got such a defect.And they don't seen to develop them all that often - if at all.
>
>Not necessary, I have many cells going bad after several charge/discharge cycles. They would get hot enough to be problematic, if not with the fuse for disconnection.
>
>> > This study does conclude that many other gross-measurement studies are probably unreliable.
>> So somebody should fund more of their studies, which they imagine to be more reliable.
>
>We don't need a PHD to know that Lithium cells can ignite.

We need commom sense, which universities don't award.

On Sunday, October 15, 2023 at 7:16:11 AM UTC-7, John Larkin wrote:
> On Sat, 14 Oct 2023 22:18:09 -0700 (PDT), Eddy Lee
> <eddy7...@gmail.com> wrote:

> >We don't need a PHD to know that Lithium cells can ignite.
> We need commom sense, which universities don't award.

Of course not; universities are few, and common sense is... by
definition, mass-produced already.
So, there's no need, no market, for such an offering.

We also need oxygen in our atmosphere; universities don't award
that, either, for the same reason.

On Monday, October 16, 2023 at 1:16:11 AM UTC+11, John Larkin wrote:
> On Sat, 14 Oct 2023 22:18:09 -0700 (PDT), Eddy Lee <eddy7...@gmail.com> wrote:
> >On Saturday, October 14, 2023 at 9:59:11?PM UTC-7, Anthony William Sloman wrote:
> >> On Sunday, October 15, 2023 at 2:08:53?AM UTC+11, John Larkin wrote:

<snip>

> >We don't need a PHD to know that Lithium cells can ignite.
>
> We need common sense, which universities don't award.

John Larkin seems to define common sense as the facility to make the same mistakes as John Larkin. He thinks that Donald Trump has it.

Universities seem to think that anybody bright enough to get admitted as an undergraduate has it - but Tulane admitted John Larkin - so they don't have to each it.
--
Bill Sloman, Sydney

whit3rd wrote:
>John Larkin wrote:
>
>
> > >We don't need a PHD to know that Lithium cells can ignite.
> > We need commom sense, which universities don't award.
>
> Of course not; universities are few, and common sense is... by
> definition, mass-produced already.
> So, there's no need, no market, for such an offering.
>
** ROTFL !! How completely asinine.

FYI imbecile: so called "common sense" is in reality far from common, cannot be taught by authoritarian institutions and is only learned by some from experience.
> We also need oxygen in our atmosphere; universities don't award
> that, either, for the same reason.

** Be almost funny if it were not so sad.

.. ... Phil

On Sun, 15 Oct 2023 23:06:52 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

>whit3rd wrote:
>>John Larkin wrote:
>>
>>
>> > >We don't need a PHD to know that Lithium cells can ignite.
>> > We need commom sense, which universities don't award.
>>
>> Of course not; universities are few, and common sense is... by
>> definition, mass-produced already.
>> So, there's no need, no market, for such an offering.
>>
>** ROTFL !! How completely asinine.
>
>FYI imbecile: so called "common sense" is in reality far from common, cannot be taught by authoritarian institutions and is only learned by some from experience.

It requires believing (and testing) basic causalities and not being
confused by subtle and infinite complexity.

The "101" level college courses explain the simple causalities, the
fundamental principles. In some areas, like physics, the
graduate-level studies respect and fine-tune those basics. In some
areas, like economics and psychology and sociology and journalism, the
more sophisticated "higher level" studies contradict the basics.

Common sense mostly requires the willingness to say "stop, that
doesn't seem right" in the face of sunk costs and peer pressure. In
other words, do what actually works.

On Tuesday, October 17, 2023 at 1:48:55 AM UTC+11, John Larkin wrote:
> On Sun, 15 Oct 2023 23:06:52 -0700 (PDT), Phil Allison
> <palli...@gmail.com> wrote:
>
> >whit3rd wrote:
> >>John Larkin wrote:
> >>
> >>
> >> > >We don't need a PHD to know that Lithium cells can ignite.
> >> > We need commom sense, which universities don't award.
> >>
> >> Of course not; universities are few, and common sense is... by
> >> definition, mass-produced already.
> >> So, there's no need, no market, for such an offering.
> >>
> >** ROTFL !! How completely asinine.
> >
> >FYI imbecile: so called "common sense" is in reality far from common, cannot be taught by authoritarian institutions and is only learned by some from experience.
>
> It requires believing (and testing) basic causalities and not being
> confused by subtle and infinite complexity.

"Infinite complexity" if it existed - and it probably can't - would be bound to be confusing. What John Larkin is actually saying is that he is a pretentious twit.
> The "101" level college courses explain the simple causalities, the fundamental principles. In some areas, like physics, the graduate-level studies respect and fine-tune those basics.

That's reasonable.

> In some areas, like economics and psychology and sociology and journalism, the more sophisticated "higher level" studies contradict the basics.

They don't, but there are number ways of doing "higher level" studies and those fields have yet to latch on a single set of insights that everybody can agree on. They don't contradicts the basics, but they do contradict one another, and the discussion is frequently acrimonious, and some partisans imagine that their particular high level insights are more basic than they actually are. Monetarists come to mind.
> Common sense mostly requires the willingness to say "stop, that doesn't seem right" in the face of sunk costs and peer pressure. In
other words, do what actually works.

But of course agreeing about what "actually" works is part of the problem. Common sense doesn't help much there.

--
Bill Sloman, Sydney

On Monday, October 16, 2023 at 7:48:55 AM UTC-7, John Larkin wrote:
> On Sun, 15 Oct 2023 23:06:52 -0700 (PDT), Phil Allison
> <palli...@gmail.com> wrote:
>
> >whit3rd wrote:
> >>John Larkin wrote:
> >>
> >>
> >> > >We don't need a PHD to know that Lithium cells can ignite.
> >> > We need commom sense, which universities don't award.
> >>
> >> Of course not; universities are few, and common sense is... by
> >> definition, mass-produced already.
> >> So, there's no need, no market, for such an offering.

> Common sense mostly requires the willingness to say "stop, that
> doesn't seem right" in the face of sunk costs and peer pressure. In
> other words, do what actually works.

That's not a definition of common sense, but of pragmatism.
The "face of sunk costs and peer pressure" doesn't
seem particularly relevant to a discussion of the concept of
'common sense'.