Video - Leaf cell torture test - virtually indestructable!

[MitchJi]

Hi,

The surprising thing is after repeated piercings, or the corner being burned off with a torch it still works (charges and discharges).

A used battery from a Nissan Leaf 3.8V 33Ah, tested for how likely to catch fire when is destroyed or in flames. We had no success make it burn. Same battery after the burn test was charged/discharged twice at 1/3C - 10A - it has 30Ah capacity remaining. Before the test this cell was under salty water for 2 hours - you can see the contact are destroyed.

When pierced through by the flat head tool, there is no explosion or eruption of flame. Instead, a rather modest wisp of smoke shyly emerges as the electrolyte next to the shorted area of the fully-charged foil pouch reacts with the influx of oxygen. Again and again, the blade descends, until the cell is riddled with holes. No fire.

Amazingly, when connected with a voltmeter afterward there are still plenty of signs of life, and when it is charged and discharged, it suffers only a slight loss of charge capacity. The video goes on to show another cell attacked with open flame (with a propane torch) with similar results.

[youtube]Jz37WycW-7E[/youtube]

 

[liveforphysics]

You can short them and overcharge them to 6-7v and reverse charge them and crush them and struggle to get more than a little puffing or a bit of white smoke.

Substantially safer cell than an A123 pouch, but also a lot lower power density.

 

[John in CR]

Substantially safer cell than an A123 pouch, but also a lot lower power density.

Yeah, I'm questioning whether 22 modules, almost half a Leaf pack, can push dual HubMonsters as well as I'd like. I'm looking for about 10C as 5-10 second peaks.

 

[liveforphysics]

Substantially safer cell than an A123 pouch, but also a lot lower power density.

Yeah, I'm questioning whether 22 modules, almost half a Leaf pack, can push dual HubMonsters as well as I'd like. I'm looking for about 10C as 5-10 second peaks.

They are saggy mofos sadly. Amazingly good choice for a commuter cell, but pretty limiting for hotrods my friend.

 

[mvly]

Substantially safer cell than an A123 pouch, but also a lot lower power density.

Yeah, I'm questioning whether 22 modules, almost half a Leaf pack, can push dual HubMonsters as well as I'd like. I'm looking for about 10C as 5-10 second peaks.

Yeah they sag quite a bit if loaded. 1C-1.5C, they are fine. Once you get more than 2C, they start to sag pretty heavily. The only option is for you to run many more in parallel. Have like 3-4 of the original pack in parallel. That should give you 180-240A. This will give you room up to 480A, but it will be heavy, and expensive, running all those packs.

 

[John in CR]

I don't mind sag so much as long as they don't get warm. The 30s20ah RC Lipo pack I have on my bike now sags over 15V when I lay on the throttle all the way. My standard has been 20s on all my other bikes, but if it's really too saggy, then I thought I'd just go to 22s to make up the difference. I ride pretty conservatively and conserve my voltage for giving electric lessons to cars and motos, so in my use the sag doesn't correspond with heat build up in the pack. My bikes are faster than I ride, so sag doesn't affect my speed except on the few occasions I making test runs for top speed.

For a low sag pack, I'm anxiously waiting for my 65-130C nanotechs to arrive. Then I can see what my SuperV can really do.

 

[ejonesss]

Substantially safer cell than an A123 pouch, but also a lot lower power density.

does the a123 pouch actually explode and burn or just puff and smoke?

the catastrophic rupture of a seam due to gas pressure could be called exploding (over inflate a ballon or even a bike tire and it explodes).

 

[melodious]

does the a123 pouch actually explode and burn or just puff and smoke?

the catastrophic rupture of a seam due to gas pressure could be called exploding (over inflate a ballon or even a bike tire and it explodes).

I'm at work & too lazy to find the youtube vid of LFP overvolting a single A123 20ah pouch cell, but yeah, they puffed & burst into flame quite dramatically (probably due to how much mass is in 20ah).

 

[liveforphysics]

[himself.melodious"]

does the a123 pouch actually explode and burn or just puff and smoke?

the catastrophic rupture of a seam due to gas pressure could be called exploding (over inflate a ballon or even a bike tire and it explodes).

I'm at work & too lazy to find the youtube vid of LFP overvolting a single A123 20ah pouch cell, but yeah, they puffed & burst into flame quite dramatically (probably due to how much mass is in 20ah). [/quote]


J. Rickard had a nice one on EVTV himself.

 

[Hillhater]

the catastrophic rupture of a seam due to gas pressure could be called exploding (over inflate a ballon or even a bike tire and it explodes).

Most people would call a balloon or tyre failure a "burst".
Explosion would normally consist of a rapid combustion process generating a pressure wave..

 

[liveforphysics]

Explosion can't really happen with a pouch cell. Inherently you can only have a low-pressure burning flammable gas release. Takes a pressure vessel type cell to have an explosion.

 

[ejonesss]

hydrogen and even acetylene can make a big bang with very low pressure.

hydrogen mythbusters got a bang from a plastic box chared with it in the hindenburg.

monster garage got a bang from acetylene filled balloon.

supposedly you get hydrogen from lithium batteries.

if you throw pure lithium metal into water it will release hydrogen and go bang.

Explosion can't really happen with a pouch cell. Inherently you can only have a low-pressure burning flammable gas release. Takes a pressure vessel type cell to have an explosion.

 

[liveforphysics]

You can't accumulate even a shot glass of flammable gasses, and the solvent decomposition gasses just aren't that impressive burning under any conditions.

Take if from a guy who has tested hundreds of pouches to catastrophic failure. I can't even think of a method that could produce anything resembling explosion.