Ebike battery fire

[guerney]

There has been comments about pouch batteries.

I was charging a 3S 1300mAhr LiPo, used in one of my RC model planes.

From hearing a noise, like plastic stretching, and there was no smake or smell, and it exploding in a fireball was maybe 5 seconds.

I don't know why I mentioned sniffing, because I lost my sense of smell after suffering the worst cold I've ever had, in November 2019 before the pandemic officially started - I got it from one of my customers who spends a lot of time gambling in casinos full of Chinese people. I regain my sense of smell occasionally, but not for long.

I'm starting to wonder if I should get a thermal imaging camera. Some phones have those built-in.

 

[flecc]

Pouch cells can explode because they don't have built-in anti explosion device and there is no air gaps between the pouches. When a cell is shorted, it will short adjacent cells and set off an explosion.
Cylindrical cells have anti explosion, steel jackets and placed inside plastic separators. They burn individually, give a lot of smoke and heat but not much fire and don't explode.
Don't buy batteries built with cheap pouch cells.
The bag battery is more susceptible to water damage than traditional plastic casings but the fire risk is the same.

From 2007 the Panasonic powered pedelec batteries used in their own e-bikes in Japan and Taiwan, plus several Derby Cycles gmbh brands on two continents and BikeTec's internationally highly respected Flyer models used pouch cells over many years.

At a time when other lithium batteries often using metal cased cells struggled to get past two years and some caught fire, these Panasonic batteries often lasted beyond five years of daily commutes, making them the best and safest batteries in use on pedelecs for well over a decade.

To which I could add that the safest and longest lived e-car batteries used in Nissan's Leaf series have tightly packed rectangular cells. So I disagree about cells without air spacing since they are well proven to be safe in well designed batteries, which have outperformed air spaced cylindrical cell batteries in both safety and longevity.

So pouch cells and air spacing are irrelevancies. The only thing that matters is the quality of cell and battery design, well proven by Tesla's abysmal record of total burn-outs and the huge numbers of fires in laptops and the like, all using cylindrical metal cased cells with some air spacing.
.

 

[Woosh]

They are prismatic cells with metal casing, not pouch cells. Modern prismatic cells have PTC thermistor, pressure release valve and nylon gaskets. Pouch cells don't.

 

[flecc]

They are prismatic cells with metal casing, not pouch cells. Modern prismatic cells have PTC thermistor, pressure release valve and nylon gaskets. Pouch cells don't.

I posted primarily about the Panasonic pouch cells batteries shown below. As you say, they have no such features, but as I've shown are very safe and reliable over many years, indeed often much safer than cylindrical cells have been:

 

[Woosh]

But cars are built with prismatic cells, not pouch cells. They are safer than pouch cells and cylindrical cells are safest. Prismatic cells are space saving.

 

[guerney]

I posted primarily about the Panasonic pouch cells batteries shown below. As you say, they have no such features, but as I've shown are very safe and reliable over many years, indeed often much safer than cylindrical cells have been:

View attachment 51796

Very impressive - I'm guessing Panasonic used a less gassy formula, by omitting Tofu AKA "Terror Chunks", as my daughter refers to them.

 

[Nealh]

As d8veh has said only one wire needs to short against the opposing polarity .of a cell.

 

[soundwave]

As d8veh has said only one wire needs to short against the opposing polarity .of a cell.

or a massive cutting disc breaches the armor

sawblaze wont the nut cos riptide broke its weapon

the batts are 60v

 

[flecc]

But cars are built with prismatic cells, not pouch cells. They are safer than pouch cells and cylindrical cells are safest. Prismatic cells are space saving.

I know that, but as I made clear, it was added information referring to air spacing, showing that wasn't always necessary.

And I still disagree that cylindrical cells are safest at present, based on actual performance. On grounds of battery safety and longevity the prismatic celled Leaf series have comprehensively outperformed other e-cars using cylindrical cells. Tesla, after a terrible history of fires and the model three launch delayed four years during which at least three of them went up in flames, are still struggling with cylindrical cell safety. They are now designing and making some of their own cells in their efforts to get it right and they have only ever used cylindrical cells.

The numbers of cylindrical cells catching fire in other applications such as laptops is now legion after so many fires and huge recalls across several major cell manufacturers.

What all this proves is that cell and battery design and implementation are paramount, regardless of the cell type. They are all dangerous when those are sub standard.
.

 

[guerney]

or a massive cutting disc breaches the armor

sawblaze wont the nut cos riptide broke its weapon

the batts are 60v

I wonder how long it'll be before solar powered war robots are as interesting to watch? "Eco Robot Wars"? Possibly starting on a microscopic scale... with robots and audiences getting larger as solar panel efficiency improves?

 

[soundwave]

those weapons' motors are pulling 4-600 amps and have a tip speed of 250mph

when one goes one way and the other in the opposite direction you hit the roof

 

[Woosh]

And I still disagree that cylindrical cells are safest at present, based on actual performance. On grounds of battery safety and longevity the prismatic celled Leaf series have comprehensively outperformed other e-cars using cylindrical cells. Tesla, after a terrible history of fires and the model three launch delayed four years during which at least three of them went up in flames, are still struggling with cylindrical cell safety. They are now designing and making some of their own cells in their efforts to get it right and they have only ever used cylindrical cells.

Citing Tesla against Nissan for comparison is not fair, they don't have the same pohilosophy. It's like using Tesla FSD stories to rubbish self driving. for e-bikes, there are very few if none examples of battery packs made with prismatic cells. This is because a) prismatic cells use mainly Lithium Iron Phosphate and b) the volumetric advantage of prismatic cells disappears if the size is too small c) high temperature is more likely with bikes than with cars.
The choice is mainly between cheap pouch cells and cylindrical cells.

 

[guerney]

those weapons' motors are pulling 4-600 amps and have a tip speed of 250mph

when one goes one way and the other in the opposite direction you hit the roof

I can't find details about their batteries - is that secret to keep competitive advantage?

 

[guerney]

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[flecc]

Citing Tesla against Nissan for comparison is not fair, they don't have the same pohilosophy. It's like using Tesla FSD stories to rubbish self driving. for e-bikes, there are very few if none examples of battery packs made with prismatic cells. This is because a) prismatic cells use mainly Lithium Iron Phosphate and b) the volumetric advantage of prismatic cells disappears if the size is too small c) high temperature is more likely with bikes than with cars.
The choice is mainly between cheap pouch cells and cylindrical cells.

All of which makes the point I am making, that it's more about the quality of design and application than cell type. As early as 2002 Panasonic were showing that lithium pouch cells did the pedelec job well in their "Will" model folding e-bike. So it was little wonder they later went the same route with their lithium generation crank drives with pouch cell batteries which proved vastly superior in the ways I've quoted.

It took years for the best cylindrical cell bike battery designs to catch up with them on reliability and longevity and even today many still fall well short with poor lifespans.

I don't have to rubbish self drive cars. Not just Tesla, they all destroy their own future by failing to perform remotely adequately. Which is probably why that subject has gone so quiet now as the truth dawns, that full self driving is only possible in prepared and idealised circumstances.
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[soundwave]

I can't find details about their batteries - is that secret to keep competitive advantage?

its one of the rules like 250lb 60v batt and 250mph max weapon speed most use custom rc batts and cost a fortune you can spend 50k on just building one of those things.

 

[Bikes4two]

As d8veh has said only one wire needs to short against the opposing polarity .of a cell.

Help me out with this one Neal, which of the many wires in a battery pack are we talking about?

If it were one of the balancing wires shorting out, surely the wire which is thin, would blow out like a fuse in very short order before any further damage would occur?

Ditto for any of the other small guage wires: BMS control (aka on/off switch/wires), charge port wires, ptc thermistor etc.

Yes, I can see a problem of the main power outlet wires short (heavy guage wires) , especially if before any built in fuse protection device.

Don't take my post as a 'dig' - I'm genuinely wanting to understand the risks here.

 

[StuartsProjects]

If it were one of the balancing wires shorting out, surely the wire which is thin, would blow out like a fuse in very short order before any further damage would occur?

Not necessarily.

Under a fault condition, there could be enough current flow to cause other parts to get hot and catch fire, but not enough current to melt the wire.

 

[Bikes4two]

..... Anyone on this forum has the facility to ignore my posts if they wish, using the "Ignore" feature.

I wouldn't want to do that as I find your posts mainly informative but I have an aversion to the re-posting of 'Click Bait' from the popular press as I think there is more a chance that it spreads ill-informed and inaccurate views rather than fosters a more realistic view of the issue under discussion.

Of course those members who read beyond the click bait headlines will hopefully get a more balanced view - I just 'worry' about those who don't and the downstream consequences of an ill-informed public.

 

[guerney]

Click Bait' from the popular press as I think there is more a chance that it spreads ill-informed and inaccurate views rather than fosters a more realistic view of the issue under discussion.

Of course those members who read beyond the click bait headlines will hopefully get a more balanced view - I just 'worry' about those who don't and the downstream consequences of an ill-informed public.

The damage has already been done by terrible and inadequate reporting read by the billions who read news websites. At least when the subject of ebike battery fire is discussed here, there's access to more experts with good quality information and experience about ebike batteries, for the relatively microscopic number of readers who visit this forum. I doubt if any of my posts are read more than a few times, over the years they are displayed on the internet. I don't think it's worth fretting that any of us have any hope whatsoever of altering mass perception about anything, not on this forum anyway - the Illuminati's forum is another story... which could be a Brexit thread sub-thread, visited by the Illuminati in secret to plot unfortunate "accidents" for us all.