I plan on using reasonably cheap powerbanks (like the Aukey Mini 3600mAh) with my own circuits, and - ideally - I'd like to have an appropriate fire extinguisher on hand in case I mess up.

I know that there's protection circuitry inside these things, but if there is a compact, cheap fire extinguisher that I can also use on LiPo batteries if the need arises, I'd like to get one.

This document claims that I do not need a class D fire extinguisher for Li-ion batteries, and that water or ABC will do (but also that you will need one for Lithium batteries - the non-rechargeable kind), but I'm not sure if that applies to lithium polymer as well. This Product Safety Datasheet for Energizer lithium polymer batteries doesn't inspire a lot of confidence.

Again, ideally this thing would be very small, easily available, and not too expensive.

  • 2
    \$\begingroup\$ From personal experience - the powder-based one is effective on a LiPo battery fire... There's still a nice charred patch on my desk at my old job though... As for overall safety I couldn't say. \$\endgroup\$ – brhans Mar 17 '16 at 20:40
  • \$\begingroup\$ @brhans Can I ask to what trouble you had to go to blow it up? I'm under the impression that they're very safe, but have no experience really. \$\endgroup\$ – Stefano Palazzo Mar 17 '16 at 20:49
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    \$\begingroup\$ They are if you don't abuse them. I was working on a new prototype device with a LiPo built-in and the external charger misbehaved while unattended (it was an 'intelligent' charger which got to end-of-charge, turned off, and then though to itself 'hmmm - maybe I should try a bit harder', and turned back on). \$\endgroup\$ – brhans Mar 17 '16 at 21:03
  • \$\begingroup\$ @brhans is that why it's your old job? :-) \$\endgroup\$ – Brian Drummond Mar 17 '16 at 21:15
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    \$\begingroup\$ @BrianDrummond :-) no - I quit a couple of months after that incident for other unrelated reasons. \$\endgroup\$ – brhans Mar 17 '16 at 21:22

I think a better way would be to isolate the fire, but there isn't much lithium in batteries.

Simple Guidelines for Using Lithium-ion Batteries

  • Lithium-ion batteries contain little lithium metal and in case of a fire they can be dowsed with water. Only lithium-metal batteries require a Class D fire extinguisher.

Lithium polymer batteries shouldn't be too different from regular lithium batteries.

  • Water interacts with lithium. If a Class D extinguisher is not available to douse a lithium-metal fire, only pour water to prevent the fire from spreading.

  • For best results dowsing a Li-ion fire, use a foam extinguisher, CO2, ABC dry chemical, powdered graphite, copper powder or soda (sodium carbonate) as you would extinguish other combustible fires. Reserve the Class D extinguishers for lithium-metal fires only.

  • If the fire of a burning lithium-ion battery cannot be extinguished, allow the pack to burn in a controlled and safe way

  • Be aware of cell propagation as each cell might be consumed on its own time table when hot. Place a seemingly burned-out pack outside for a time.

Another good way is fire isolation get some bricks or cinder blocks and make a flame "container", if you mess up the heat will go into the brick slowly.

  • \$\begingroup\$ No difference between Li-ion and LiPo? \$\endgroup\$ – Stefano Palazzo Mar 19 '16 at 12:40
  • \$\begingroup\$ As far as the amount of lithium in them. \$\endgroup\$ – Voltage Spike Mar 21 '16 at 17:12
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    \$\begingroup\$ I've since bought an ABC type fire extinguisher, and I'm hoping to never update the question on whether it worked or not. :) \$\endgroup\$ – Stefano Palazzo Mar 29 '16 at 14:02
  • 1
    \$\begingroup\$ Maybe you should burn one up just for fun :) \$\endgroup\$ – Voltage Spike Mar 29 '16 at 15:32

I've been doing LOTS of research on this for the past several hours on Google. Here is what I've found:

Lithium METAL cells (coin cells like the common CR-2032 and possibly other Li-primary batteries, but I'm not as sure) truly have uncombined lithium metal in them. Li is the lightest of the alkali metals (along with Na/sodium, K/potassium, Ru/rubidium, and Cs/cesium (caesium in the UK), it will react with ANY oxidizer, but being so light is normally isn't violent like the others. Unlike the others, it will also react with nitrogen at room temperature, which makes fighting fires interesting (Class-D lithium extinguishers use argon as the driving gas for that reason). The point is that if these cells physically open for any reason you WILL get a fire or at least a lot of heat. If it's just one cell (like a coin) and not ignited yet, and you have bunch of oil nearby, you may get away with throwing it in as all the alkali (and many of the heavier alkaline) metals are stored under mineral oil. The point is to exclude air, water, and anything containing them (like most extinguisher agents).

Meanwhile, Lithium-ION cells should not, under normal circumstances, contain ANY free metal. The danger is that the electrolyte is often highly flammable, but you can treat it as you would, say, gasoline. It won't spontaneously ignite in water or air, AFAIK, but opening the cell would definitely kill it. Thus (A)BC should work fine.

Of course there's a catch--otherwise you wouldn't need the Battery Management Circuits (BMC's): over-(dis)charge can cause electrolysis which can create free metal. If that happens, THEN you could spontaneously ignite like the Note-7's did. A malfunctioning charger (as related above) or (more likely in production cells/packs) a short in the cells/packs/etc is the most likely cause.

It has also occurred to me that, with the only real exception (outside of factories and warehouses) being electric cars, that you won't have enough lithium around in one place to be a major threat on its own (unless holding it as it goes off, of course): rather, the danger is as an igniter lighting up regular flammable materials like furniture, carpet, etc. In my case, this really worries me because I have several old Li-ion cells in my storage unit inside devices that are likely discharged or nearly so. Some are single cell (phones) and will just go to zero volts. However, there are also laptop and radio packs that have 2-3 cells in series, and these could over-discharge a cell and theoretically cause a fire. THIS worries me but I haven't removed them yet.

  • \$\begingroup\$ Are you sure this is an answer to the question? \$\endgroup\$ – Dmitry Grigoryev Jul 10 '17 at 12:28
  • \$\begingroup\$ Correct answer - just add that the fire extinguisher companies say you should use a Class B fire extinguisher \$\endgroup\$ – Cameron Lowell Palmer Feb 2 '18 at 5:41

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