China accidents and ebike fires

[The Toecutter]

How is this not the most watched video on youtube? This is hilarious. I need one.

I suspect, but have no evidence for and cannot prove, that the algorithm is throttling this man, perhaps because his social credit score is low. If your social credit score in China is sufficiently low, they will deny you a drivers' license, but this man built a vehicle that in China, doesn't require one. I do know for a fact that the view count is underreported, because at one time, I'd shown this video to at least 20 people, including two automotive journalists at The Autopian, but the view count was only 5.

It is now supposedly only 30. I suspect the real view count is 100x that.

 

[amberwolf]

I wish I knew the language he was speaking so I could get more out of the video, because it was amazing.

I don't know which dialect it is, but I am pretty sure it is Chinese. (I don't know enough to even tell the difference between Mandarin and the many others Varieties of Chinese - Wikipedia )

 

[onemorejoltwarden]

Chinese E-Bikes are Exploding like Crazy - Self Destructing Spectacularly
The above is on target

Fire and Safety issues will dog us until we deal with theses issues like professionals
Otherwise it's a high risk hobby, like hoverboards

 

[The Toecutter]

Chinese E-Bikes are Exploding like Crazy - Self Destructing Spectacularly
The above is on target

Fire and Safety issues will dog us until we deal with theses issues like professionals
Otherwise it's a high risk hobby, like hoverboards

LiFePO4 batteries almost completely solve the issue. Instead of burning your house down, they'll release toxic smoke. Their gravimetric energy density is improving, and the high-end ones regarding this spec are getting within 25% that of high-end LiIon. There are a number of them that are around 220 Wh/kg, which is significantly higher than LiIon typically was 15 years ago.

The microcar built in the video I previously posted used scrap lead acids. I suppose that is all he could find. LiIon batteries tend to be reused for other bikes or applications, instead of just scrapped, provided they are in sufficient condition to have a 2nd or 3rd or Nth use case.

 

[amberwolf]

LiIon batteries tend to be reused for other bikes or applications, instead of just scrapped, provided they are in sufficient condition to have a 2nd or 3rd or Nth use case.

And when they aren't, they just get built into "new" battery packs and sold for cheap as 100bajillion Ah shrinkwrap packs to noobs.

 

[Hillhater]

LiFePO4 batteries almost completely solve the issue. Instead of burning your house down, they'll release toxic smoke

You may want to take a rain check on that…
BYD are known to specialise in LFP battery production and use, however, they also have a high incidence of battery fires in their cars and busses !

In China, 640 EVs caught fire in the first quarter of 2022, up 32 percent | WapCar

Although electric vehicles (EV) are heralded as the future of mobility, however, it seems that EV manufacturers has yet to get a handle on the issue of battery catching fire. It is barely summer in Ch

www.wapcar.my

 

[The Toecutter]

You may want to take a rain check on that…
BYD are known to specialise in LFP battery production and use, however, they also have a high incidence of battery fires in their cars and busses !

Not all of BYD's cars use LiFePO4. The LiFePO4 batteries can develop dendrites on the anode material if you charge them when it is below 32F in temperature(although this won't happen at extremely low currents), and that can turn them into fire hazards. Nominally, this is an otherwise stable chemistry, at least when compared to all of the other lithium-based batteries available(excepting LiTO). You can puncture most LiFePO4 cells, and maintain a confident expectation that it won't immediately shoot flames out. There are exceptions, as not all of them are built the same. There are also LiFePO4 batteries from China that really aren't and are mis-labelled.

 

[The Toecutter]

And when they aren't, they just get built into "new" battery packs and sold for cheap as 100bajillion Ah shrinkwrap packs to noobs.

A friend of mine bought one of those as a joke/curiosity. It definitely did not deliver its nameplate rating, and caught fire when he put it on the charger. Which we both expected it would do.

 

[Hillhater]

Not all of BYD's cars use LiFePO4.

Maybe not, ..but most of them do, and BYD have the most battery fires in China.
some of the more recent fires have been the BYD “HAN” which uses the popular “Blade” LFP cell system.
so how can you state that LiFePO4 eliminates most of the fire risk .?
It may be “safer” than LiCo , but it obviously does not eliminate the fire risk.

 

[The Toecutter]

some of the more recent fires have been the BYD “HAN” which uses the popular “Blade” LFP cell system.
so how can you state that LiFePO4 eliminates most of the fire risk .?

I think that fire risk is largely because of the electronics in the "Blade" system. I posted a video above demonstrating what LiFePO4 does when you puncture it. Do that to LiIon, and 100% of the time, it will burst into flames. LiFePO4 indeed almost eliminates the risk. Key word being almost, which is not the same word as entirely.

I'm a proponent of "dumb" systems that use large AH LiFePO4 batteries configured as a single series string. After an initial bottom balancing, and if all of the interconnects are done correctly, they will stay stable for decades and all remain within 0.001V of each other. Without a BMS. A BMS can actually damage them if you let them sit for long enough. I like my EVs "dumb" with the electronics kept to a minimum. The car I converted to electric has remained mostly analogue, without all of the tech fetishism found in modern EVs that is difficult to repair, in favor of "dumb" systems that can be serviced with basic hand tools. THIS is how you build an EV to last a human lifetime, not having a rat's nest of wires and sensors run by a CANBUS locked behind proprietary tools and software where your car bricks if you crack the touch screen. Instead, "Bubba" mechanic, the illiterate high school dropout down the street, would be able to fix this EV over a few beers with his cheap tools from Harbor Freight, something he can't do with any modern EV. What's better for the environment?

Also compare the statistics with gasoline cars catching fire, and you will find that even LiIon EVs are generally favorable on that metric.

Government data show gasoline vehicles are up to 100x more prone to fires than EVs

LiFePO4 are of course greatly favorable to LiIon on that same metric.

Of course, my ebike uses LiIon. Molicel P42A. You bet your ass I have a BMS on that. The only chemistries I would ever use without a BMS are all going to be configured as single series strings, and are PbA, NiCd, NiFe, LiTO, and LiFePO4. My electric trike has electronics more complicated than my electric Triumph GT6 conversion.

 

[amberwolf]

Do that to LiIon, and 100% of the time, it will burst into flames.

You would expect that, but not necessarily. However, I still treat all batteries, of any chemistry, as if they are like the second example below.

Here's a defective self-discharged hobbyking RC LiPo pouch (dont' recall which brand) being charged at high current (starting at ~100A, load so high that the voltage wouldn't go up over 4v IIRC) from a huge linear supply, then punctured, just to see what happens. You can hear the supply humming....

Partly from the rep of RC LiPo and mostly because the cell was already obviously internally damaged, I expected flames during the overcharge, and only got a little smoke, and definitely thought for sure it'd catch fire when I repeatedly slammed the screwdriver into it, but....nothing, as I jokingly say "lipo's perfectly safe" :lol:


The second try was more interesting, and did produce flames at 5v and about 30A, presumably it wasn't as internally shorted as the first one.

LiveForPhysics has a video around here somewhere doing this kind of test to a bunch of different cell types and chemistries.

 

[The Toecutter]

You would expect that, but not necessarily. However, I still treat all batteries, of any chemistry, as if they are like the second example below.

As you should.

Interesting that you punctured a LiPo without it catching fire. That is arguably the most volatile of lithium-based chemistries.

 

[Hillhater]

As AW mentioned, there were videos on here many years ago ( 8-10 ?, early days of the Hobby King use) with various users testing different brands of LiPo/LiCo pouches,….over voltage charging, over discharging, shorting, and puncturing.
the results were very variable depending on the brand, ranging from the predictable violent explosive flames, through to gentle burning with no explosion, simple smoking with no flames, and some with apparently little reaction ?

 

[Hillhater]

I posted a video above demonstrating what LiFePO4 does when you puncture it. Do that to LiIon, and 100% of the time, it will burst into flames. LiFePO4 indeed almost eliminates the risk

Maybe so, but most of the EV fires reported are not the result of mechanical damage.
they frequently occurr whilst charging, or even driving along a highway,…sometimes whilst just standing in a parking lot .
Cetainly there is a fault somewhere that initiates the “thermal event” but it is obvious that LiFePo4 is not immune to propogating a serious fire.