Computing stuff tied to the physical world

LiPo bulge

In Hardware on May 19, 2011 at 00:01

Speaking of Lithium Polymer batteries…

Last week, I was working on the (2007-vintage?) MacBook Pro now used by my wife Liesbeth, who uses it every day as desktop machine with an external keyboard and mouse hooked up all the time. Then I noticed that for some reason, the built-in trackpad had stopped working…

Here’s what happened:

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The battery pack had bulged to almost twice its normal thickness. Here’s a good battery pack for comparison:

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Sure enough, that bulge pressed up very hard against the mouse pad. I’m surprised it didn’t bend or damage anything else in the laptop! Removing it made the trackpad work again, BTW.

These battery packs are quite large and can store a serious amount of energy:

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Ok, now since that pack is hosed anyway, I decided to take it apart. Which wasn’t relly hard, considering how much of the innards were already exposed:

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After prying off the aluminum cover, which was glued on, this came out:

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You can see the battery protection / charge circuits, and what appear to be three sets of LiPo batteries in a sturdy plastic pouch. And the middle one sure doesn’t look right:

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I’ve stopped there, afraid to open up the battery and expose the Lithium to air, which as far as I understand could cause it to spontaneously catch fire. Well, that’s what Sodium (Na) does, anyway.

Given that the battery was produced 5 years ago and has given me several years of good service, I don’t really mind. Just need to get rid of this chemical waste in the proper manner.

Or did I narrowly escape a major disaster?

  1. Neither sodium nor lithium will spontaneously catch fire upon exposure to air. Also, lithium ion and lithium polymer cells don’t actually contain elemental lithium (although some other types of lithium cells do).

    • Ah, wait – that was sodium dropped in water :) – ok, thx, good to know.

    • Although if the air happens to be particularly moist it could start fizzing at least.

  2. Had exactly the same thing happen with my older MBP 17″ – twice. The second time it happened, the machine was in semi permanent use on a stand for a few months (always on power) and the LiPo actually bulged more than 2 cm – it got twice as thick. Nasty…

  3. I had the same thing happen to one of my batteries with that same model. I took the machine to the Apple store and put it upside down (battery up) on the Genius Bar in front of a lot of customers. Amazingly I got their attention very fast as they took the battery quickly to hide it and gave me a new one.

    You might try taking it to a local store and see if they will replace it as it was a well known defect in the battery line.

    • I hope you didn’t accidentally roll up to the genius bar on a very busy Saturday ;-)

  4. To my understanding, the chemicals in lithium batteries are perfectly recyclable. The public not knowing this helps to feed the ‘lithium shortage myth’ (all stories that we will run out of lithium if everyone starts using electric cars all came down to one source, which wasn’t perfectly correct either). So the more reason for mentioning ‘get the batteries recycled’ rather than ‘get rid of the chemical waste’.

  5. See also: It seems that Apple considers a bulging battery a safety hazard- at least, some of the time!

  6. I wonder if Apple has a patent on this unique hand warming feature? :o)

    Rather scary, I’ve never seen a LiPo go like this, although I do have a rather knackered AA NiMh which managed to short out when thrown in a bag with a few of its friends, some small change and a bunch of keys (possibly not the best storage idea I’ve had!). I only discovered it by accident the other day, it’s completely toast, 0.3v on the meter and distinct signs of some serious heating in that the plastic wrapper has partially melted and the cell has bulged 1-2mm in length.

    Apart from that I feel rather left out. Despite owning several laptop models which earnt a battery fault recall, I never seemed to get one from the dodgy batch :-(

  7. Been working with LiPos for my airmodelling hobby, i can tell you that a bulged lipo is a fire hazard. Poking the Lipo WILL combust almost instantly. Lipos cannot be recycled must be thrown to garbage AFTER they have been properly discharged. DO NOT By any circumstance ReCharge it. What i usually do to my hobby LiPos is connect an LED with a resistor and leave it outside for a week. I then measure the Voltage of the packs and if it near 0 (0.1 or 0.2 is ok) i then through them away. All these steps have being aquired from various discussions on aeromodelling forums over the years. ( is one of the largest)


    • I think this calls for another JC destruction weblog post, with video :-)

      Although I fear his back garden might not be big enough… I know of a nice concrete farm yard which would be perfect, but I don’t think this battery would be a good thing to put in the post.

      Time to wander to the Apple store and quote the WEEEEEEEE (it might possibly only have 3 E’s) disposal directive :-)

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