Interesting Tesla battery fire

Tony_Cape · 2018-11-27T13:37:10.000Z

Interesting YouTube clip.

Henk4U2 · 2018-11-27T14:04:01.000Z

Anything can be a potential danger (planes, trains, automobiles, bikes, guns, fugu fish).
Unless they are handled by people who know what they are doing.

You would not want me to be the captain of the Jumbo-jet you are about to board.

EasyB · 2018-11-27T23:33:17.000Z

Pretty annoying, they don’t say anything about what could have caused the cell to overheat.

snakebite · 2018-11-29T13:43:48.000Z

probably charging with a golf car charger meant for use with lead acid batts?
with predictable outcome.
i have several tesla modules here and they have a bms for this very reason.
as you can see they can turn into a commercial display fireworks bank if abused!

Tom_Tom · 2018-11-29T14:27:39.000Z

What really made me cringe was seeing the chap handling the destroyed cells with bare hands

How much fluorine was released in that fire, in various compounds, including HF ? How much did they breathe in ?

“Toxic fluoride gas emissions from lithium-ion battery fires”

PubMed Central (PMC)

Toxic fluoride gas emissions from lithium-ion battery fires

Lithium-ion battery fires generate intense heat and considerable amounts of gas and smoke. Although the emission of toxic gases can be a larger threat than the heat, the knowledge of such emissions is limited. This paper presents quantitative...

“Significant amounts of HF, ranging between 20 and 200 mg/Wh of nominal battery energy capacity, were detected from the burning Li-ion batteries. The measured HF levels, verified using two independent measurement methods, indicate that HF can pose a serious toxic threat, especially for large Li-ion batteries and in confined environments. The amounts of HF released from burning Li-ion batteries are presented as mg/Wh. If extrapolated for large battery packs the amounts would be 2–20 kg for a 100 kWh battery system, e.g. an electric vehicle and 20–200 kg for a 1000 kWh battery system, e.g. a small stationary energy storage. The immediate dangerous to life or health (IDLH) level for HF is 0.025 g/m3 (30 ppm)22 and the lethal 10 minutes HF toxicity value (AEGL-3) is 0.0139 g/m3 (170 ppm)23. The release of hydrogen fluoride from a Li-ion battery fire can therefore be a severe risk and an even greater risk in confined or semi-confined spaces.”

I foresee a large insurance bill (assuming it was insured), even just to re-spray all those other cars that got damaged.

EasyB · 2018-11-29T14:30:48.000Z

Yep I think you’re right. This is from the YouTube comments and the video maker “liked” it, indicating that’s what happened.

I’m guessing the 2 Tesla modules connected in series was 12s and they used the 48v charger that came with daisy to charge it. The Tesla Modules can only be charged to about 50.4v, while a 48v lead acid charger will put out at least 54v once in the CV phase.

Without a BMS to bleed off everything the charger was sending it, eventually all the cells were overcharged, and one brick with the highest voltage reached its ignition point first. Then quickly spread.

So my guess is unsupervised charging (human or BMS) with the wrong voltage of a 12s battery pack

These guys must be very ignorant of li ion batteries. There’s only a couple things you can’t do, and overcharging them is one of them. So using a random lead acid charger is just really dumb.

This was something I didn’t fully understand. I understand that overcharging is bad and can damage the electrodes, but would overcharging at a modest current still cause thermal runaway? According to this paper it does.
https://www.researchgate.net/publication/226507209_Failure_mechanism_of_Li-ion_battery_at_overcharge_conditions

Cereal_killer · 2018-11-29T14:31:28.000Z

I saw this video earlier this week (posted here). My biggest thought was about how the FD shows up and starts dumping water on it

Isn’t it a general rule you fight a Li fire with dry CO2 extinguishers only?

Tom_Tom · 2018-11-29T15:16:25.000Z

You can’t put out a runaway lithium cell. It’s not a “fire”, all the ingredients are contained in the cell itself. The flames that you see are a by-product of the escaping gases then burning with atmospheric oxygen, but the major release of energy has already happened inside the cell, and is pretty much un-stoppable.

Clearly the venting system of these cells wasn’t very effective, given the way they flew about like firecrackers.

And obviously this was a propagating failure, the cells didn’t all decide to let go simultaneously (that would have been impressive).

Consider: a fully stoked 357 Magnum bullet carries say 600 ft-lbs of energy. That’s 813 Joules.

A 3000 mAh 18650, nominal 3.7V contains 40,000 Joules.

Let’s hope nobody figures out how to make a mini rail-gun in portable size.

BlueSwordM · 2018-11-29T15:25:08.000Z

During a thermal runaway, you either want to use sand, or actually water.

Since the cell undergoes rapid degradation, it uses its own oxygen supply to keep itself lit. You want to use sand to prevent as much fire to spread to the cells as possible.

And since it’s lithium ion and not pure lithium, to lower the pack temperature, a strong water mist can be used to lower the thermal runway temperature to slow down the chemical degradation.

Kame_Sennin · 2018-11-29T15:41:16.000Z

Tom Tom:

A 3000 mAh 18650, nominal 3.7V contains 40,000 Joules. Let’s hope nobody figures out how to make a mini rail-gun in portable size.

And a bottle of gasoline the size of a 18650 contains about 1,000,000 Joules ... but we agree that the required oxygen is not included

Tom_Tom · 2018-11-29T15:44:25.000Z

A bucket of sand is carried on aeroplanes these days, hopefully to dunk any burning-up iPhones or Samsungs, or laptops that let go.

I wouldn’t want to rely on it, but at least it’s there.

Being in a tin tube at 40,000 feet with a battery “fire” going off is the stuff of nightmares.

sb56637 · 2018-11-29T16:01:00.000Z

Haaaaa, those dogs! Doesn’t matter how irrationally you act or as confounded as you might be, you can always count on a thumbs up from your loyal dog. :+1:

hank · 2018-11-29T16:45:48.000Z

Hmmm. And people are homebuilding “Powerwall” storage too, eh?
The future looks bright, and smoky.

Tom_Tom · 2018-12-01T04:00:32.000Z

sb56637:

Haaaaa, those dogs! Doesn’t matter how irrationally you act or as confounded as you might be, you can always count on a thumbs up from your loyal dog. :+1: :+1:

,

My loyal dog would have more sense and run far away (I live in a semi-rural place). Well, eventually back to the house, or to a neighbour. He’s had to be gathered up a couple of times, fortunately I have good neighbours who like him, and he likes them, and we all look out for each other.

He is completely calm with clay shooting, big rifles, even fireworks (we really know how to do these in Sussex and Kent, it’s a tradition). But that is another story.