Computing stuff tied to the physical world

Lithium theatrics

In Hardware on Apr 16, 2012 at 00:01

As an alternative to supercaps, I recently ordered a Lithium rechargeable battery from Digikey:

ML614 TZ21

It’s not quite what you might think, though: its size is only 6.8 x 1.4 mm, with a tiny 3.4 mAh capacity :)

Got ten of them, as part of a larger order, and they came packaged as follows:

DSC 3039

So far so good, but now the crazy part. These batteries were sent out in a separate 23x23x5 cm box:

DSC 3040

With a warning label …

DSC 3041

… and another warning label:

DSC 3042

The max discharge current of these things is 1.5 mA according to the specs. I doubt they’ll even go up to 15 mA when shorted! By the way, does that dented corner qualify as “damaged” ? … I want my money back! :)

Get real – or better still, read Bruce Schneier‘s works!

PS. Please don’t get me wrong: fire risks are very real – it’s just that the above cells have virtually no energy…

  1. Security theatre sounds bang on the money.

    I can’t help but wonder what the California special handling would entail (visions of men in full yellow hazmat suits spring to mind).

    As you’ve got so may JC, how about a destruction test in the back garden with video coverage and a 1 wire thermometer strapped to one?

    Yes, I know, probably a bit of a non-event, but you never know, the labels might actually be true!

  2. The danger with lithium batteries is the chemical energy of the batteries, not the electrical energy. When damaged, they’re just plain flammable.

  3. It’s not the electrical stuff that matters, but the chemical. When exposed to air and moisture, lithium can burn violently.

  4. If the max discharge current is 1.5 mA how would you get 15 mA when shorted?

    • Allowed / within spec versus what-happens-if-I-ignore-the-specs was my thinking.

  5. It is funny to see that these batteries still store much more power than the 0.470F supercaps you used earlier. Supercap: 0.13 mAh (3.6 F = 1 mAh) Lithium: 3.4 mAh 26 times as much.

  6. The actual lithium content of these is very small, a CR1226 is 2x this size and only has .006 grams (.0002 oz) of lithium in it. This seems to be overkill on the part of the shipper. They may ship larger cells and the shipping department was given instructions on the proper packaging for the larger cells and carried it too far. I would like to see additional protection on those cells to prevent the contacts from touching, The soft plastic bags do not protect very well. It would probably only mean a dead cell, but still. BTW that damage on a box for a larger cell would be suspect. Interestingly, I received a box containing 50 5000mAh (5Ah) lithium cells from china with no markings like that on it. The box had very little packaging other than a cardboard (cheap) box and plastic heatshrinked around pairs of cells. On the very top,inside of the package were 2 plastic wristbands with flashing LEDs in them. The customs declaration said “toys with lithium cells inside”

  7. I agree the packaging/hazard label seems excessive, but unfortunately the hazards of shipping these around are very real (and many break the rules as bratib illustrates). I recall the Dubai UPS crash which puzzled the flying forums on how two seasoned pilots reacted so inadequately to a hold smoke alarm warning. Turns out the cockpit was engulfed in smoke so thick they could not read the instruments and missed the runway for the emergency return. The controls burnt out soon after and their fate was sealed.

    Since a punctured cell goes into thermal runaway supplying its own oxygen, none of the standard fire extinguisher “flood” gases work. The heat released is sufficient to trigger neighbouring good cells. Standard practise now is to ship a limited total mass in a heavier container – so declaring even a few grams of coin cells is still important for segregation & mass count.

  8. @Rikkert Koppes: Most types of lithium cells don’t actually contain elemental lithium, rather various lithium compounds which don’t react violently with water. However, some cells do contain elemental lithium – these tend to be non-rechargable. Also note that lithium itself does react quickly with air but not quick enough to cause any real trouble – you need some water for that.

  9. BTW, these look like primaries(non-rechargeable), be careful!

  10. I just received 20 Cr2320 batteries wrapped in a bit of plastic in a bubble envelope.

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