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News Apple PowerBook goes up in flames in London office

Discussion in 'Article Discussion' started by Sifter3000, 27 Feb 2009.

  1. Phil Rhodes

    Phil Rhodes Hypernobber

    27 Jul 2006
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    Herewith follows a factoid report designed to minimise the promulgation of this sort of misinformation.

    There is by design no lithium metal in lithium-ion batteries. There were lithium metal batteries during the 70s, but they were horribly dangerous and really used only for situations where there was no alternative to achieve the required levels of performance, particularly in things like military guided missile systems.

    The lithium in a modern battery is supposed to be in the form of a lithium salt - a compound with other things. The problem happens when they're overcharged, overdischarged, or asked to supply too much current. Particularly, if you overcharge the cell, you will begin to plate lithium out of the compound as a metallic coating on the electrondes. Since all lithium ion cells contain a certain amount of air and water as an inevitable part of manufacturing tolerances, and lithium is pyrophoric in contact with those substances, having metallic lithium inside your lithium-ion battery is a near guarantee of a seriously unpleasant flammable-metal fire. These fires are extremely difficult to extinguish, burn very hot, and produce noxious fumes.

    However, this almost certainly isn't what happened here. The famously-defective Sony cells were contaminated with metal particles which pierced the insulating separator that keeps the anode and cathode apart. This short-ciruicts the cell. Lithium ion cells have an extremely high energy density, and a short causes the cell to dump almost all of that energy into its internal structure very quickly. This causes it to blow its emergency vent (as opposed to exploding like a hand grenade, which is what it'd do otherwise). The impressive jets of flame visible in all those youtube videos are mainly just burning plastic and electrolyte being blown out of the cell under pressure. Nothing to do with a flammable metal fire.

    Regardless it is difficult extinguish and isn't something you'd want happening on, say, an airliner, so you can understand caution.

    Has worked with these things a lot.
  2. Pricester

    Pricester What's a Dremel?

    25 Aug 2002
    Likes Received:
    Can someone please explain why the words "IT Manager" in the news article provide a pop-up link to advertise Server Management?

    Bit-Tech - that's strike one.
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