Test/Review of UltraFire BRC18650 3000mAh (Red-silver) 2015

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SIGShooter
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hank wrote:
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I sent him some articles on how dangerous they were and he immediately tossed it.

Tossed it where??


Our company has a container for battery disposal, which is where he put them. It’s picked up along with our used desktops, laptops, and other hardware. After that I have no idea what happens to the stuff. I suppose it’s possible that the batteries will come back as “ultrafires” Sad
FlashPilot
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I always thought BRC was a Chinese acronym for “mini exploding hand grenade”.

dchomak
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Someone correct me if I’m wrong, but I am guessing that when a cell vents or explodes, it is all the energy stored in the cell when it is charged up. All of that stored energy is released suddenly and it could be argued that the UltraFires are safer because they don’t store as much energy!
(A safety feature) Wink

In other words, can a discharged cell vent or explode? Where would the energy come from?

hank
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Where would the energy come from?

I’m no expert, but I ‘oogled, and as I understand it, you never get to zero with this chemistry unless you do something like drop the cell into a bucket of salt water and wait a long time. All you need is a slight heat source or tiny spark if the solvent chemicals have leaked, as each battery is made using organic solvents, liquid, in two separate compartments with a very thin membrane in between. Crystals start growing after a while, and grow slowly — and if a crystal punctures the membrane the chemicals mix and heat is released. That’s why you don’t toss these into the ordinary trash — it can take weeks or months before one cooks off.

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lithium dendrite structures known to degrade lithium-ion batteries…. form when metallic lithium takes root on a battery’s anode and begins growing haphazardly. If the dendrites grow too large, they can puncture the divider between the electrodes and short-circuit the cell, resulting in catastrophic battery failure.

http://www.hpcwire.com/off-the-wire/ornl-captures-real-time-images-of-st...

Quote:
In a separator failure, that same kind of short happens inside the lithium-ion battery. Since lithium-ion batteries are so energetic, they get very hot. The heat causes the battery to vent the organic solvent used as an electrolyte, and the heat (or a nearby spark) can light it.

http://electronics.howstuffworks.com/everyday-tech/lithium-ion-battery2.htm

Oh — and, you’re relying on a good material being used for the membrane.

Just any old thin crap sheet will work for a while, long enough to get the stuff shipped out.

Cutting corners is a lot of the problem.

HKJ
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dchomak wrote:
In other words, can a discharged cell vent or explode? Where would the energy come from?

It can, the electric energy is only part of the energy in the cell, the chemicals and other stuff it is made of contains many more times energy. I have seen numbers like: Electric energy 36kJ (10Wh), other stuff: 280kJ (I do not know how precise this number is).

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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