Ask HN: Just how dangerous are lithium-ion batteries? | Hacker News Reader

Ask HN: Just how dangerous are lithium-ion batteries?

4 pointsprmph6 comments

I just read that they can release hydrofluoric acid (HF) and other toxic chemicals under conditions of chemical leakages, overcharging, external heating, or explosions.

Now, hydrofluoric acid (HF) in particular is extremely toxic, whether inhaled, touched, or ingested. An explosion can also cause a fire.

How concerned should we be about this release occurring in common household electronics like phones, laptops, and battery packs?

Is the risk greater for old, depleted, or swollen batteries? Are LiFePO4 batteries safer?

What tips can help keep one safe?

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Well, you can start with https://en.wikipedia.org/wiki/Lithium-ion_battery#Safety

How big an "event" occurs when a battery is damaged to the point of self-immolation is correlated with its level of charge. A fully-depleted battery won't do much if damaged. A fully charged battery will vary from "it gets really hot" to "boom," depending on how it is constructed. Thus, if you have a LiIon battery that you want to dispose of, it's always better to safely discharge it as low as it will go before storing or transporting it.

Lithium-polymer ("pouch") cells are cheap to make and are incredibly energy-dense compared cylindrical cells (such as the classic 18650), but are far more likely to go kaboom. Unfortunately, they make up the majority of our Lithium-powered gadgets.

LiFePo4 cells are MUCH more stable than either traditional lithium style, handle over-charging better, and survive far more charge/discharge cycles. The tradeoffs are that they are a bit more expensive and are slightly less energy-dense. I have also never seen them in "pouch" form, so I don't know if they can ever replace lithium-polymer for cell phones/tablets. But they are pretty popular now in power tools and car/bike batteries.

Any suggestions for safely discharging? I have two very old puffed up phone batteries, both removed from their devices, but I can't figure out how to discharge them since they won't fit in their devices anymore and I don't have any background in safely handling stored electricity.

I've looked for advice online, but it mostly requires tools I don't have, or sounds like someone completely made it up and it isn't safe at all.

Disclaimer: I'm a co-founder of Gouach, the repairable e-bike battery.

Because we're making a repairable battery, we're VERY careful about safety, which is why we developed a fireproof casing.

If you want to see some battery fires, go check our casing comparison video :) https://www.youtube.com/watch?v=tJETffg0kFc

I used to work at a battery recycling company and one time I accidentally let one slip through and sent it off to the place where they do something with them involving fire. This battery was maybe the size of a TV remote and caused an explosion. However, they are just about as energy dense as they get and happen to weigh nothing. But you can’t put it out with water if it catches fire.

They are safe barring manufacturing defects. The large enterprise I worked for had 6 fire incidents over 4 years, 5 of which were in a single lot of laptops. (~2000 laptops out of ~150k total)

Swelling is much more common (I’d estimate hundreds of incidents over a similar period). IT teams should have procedures for high risk batteries and containment plans for each significant location. In most cases that means 5 gallon buckets with cat litter or vermiculite.

I have this classic "Bag Check" XKCD cartoon taped to my wall. The TSA actually did respond to this cartoon. Some of the comments in that response may be helpful to you.

Phones and Laptops have started fires in peoples homes and on airplanes. The risks are real. Today we have somewhat better charger designs. The most often failure is using a replacement battery that has fake certifications.

In my Day Job I have to deal with UL1642 that deals with Lithium Batteries, you should look that up. I've had one China based manufacture try to self-certify their products with this comment: "Battery burst into flames but did not ignite Cheesecloth". Thereby proving I could use their product. Sorry, I can't have any flames.

https://xkcd.com/651/

https://web.archive.org/web/20170630101802/https://www.tsa.g...

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