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Comment by jacquesm | Hacker News Reader

I absolutely loathe the degree to which manufacturers will embed LiPo's into just about everything including wearables without disclosing the fact. If you're clever about this sort of stuff and see a certain form factor coupled with larger than expected operating times you can infer the presence of LiPo's with some accuracy but your average consumer doesn't stand a chance and has no idea what the difference between all these different battery chemistries is in the first place and what the implications are.

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But what good would a wearable or phone be with a nicad battery? Sure, there are dangers with lithium chemistry batteries, but sadly there are no viable alternatives. And as far as manufacturers not disclosing, what do you want for disclosure? Should we add yet another useless warning label to ignore, like the prop 65 warnings?

These incidents are relatively rare in consumer devices (so exempting RC lipos and cheap knockoff products with no protection).

https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery or LiFePO4 has much better safety properties. Any device sold to consumers should be required to have temperature monitoring, over voltage and over current protection. If it fails any onboard safety check it should render itself inoperable.

That sounds like a good development. I'm especially concerned about stuff worn against the body (earbuds, sports wearables, watches, cellphones). Laptops and tablets are also potentially dangerous but it's not as if every fuck up will immediately lead to injury.

I review flashlights and headlamps as a hobby. Many modern high-powered ones use removable Li-ion cells, most commonly 18650 size.

Temperature monitoring has become very common. The primary heat source is almost always the LED, not the battery, but it would be sufficient to detect a battery nearing thermal runaway. Low-voltage protection is common, but sometimes only a warning blink rather than a hard cutoff based on the idea that leaving the user in the dark might be worse than damaging a battery.

Some models have onboard charging, most often through MicroUSB. Correctly charging a single Li-ion cell is not difficult, and I haven't seen one get it seriously wrong yet.

LiFePO4 has seen a little use, but is not popular due to its much lower energy density. I suspect this has kept it out of other portable devices as well since users always seem to want longer runtime in ever smaller devices.

It was popular for pro power tools for a while. Those get a lot of abuse, and people are constantly changing battery packs so they max out on charging cycles. DeWalt used LiFePO4 from A123 Systems. But they seem to have given that up.

I honestly wonder why. I developed a portable small-quantity project a few years ago and designed in a 20AH LiFePO4 battery pack; it seemed like the only sane choice. The cost was slightly higher and density was slightly lower, but the difference was less than 10%. Not having to be concerned with battery failure modes was a huge advantage. But those factors must be different at larger scales; the largest scale I can think of where density matters would be for a commercial electric 18-wheeler tractor; what chemistry do those use?

Price. Ordinary lithium-ion batteries have dropped in price due to volume production and competition. LiFePO4, not so much.

Unfortunately we're getting to the point where there's rarely any choice.

30 years ago we didn't walk around with half a dozen bombs on our body. As a society we have decided that the benefits outweigh the risk, but it's still easy to not walk around with battery devices in our pockets/bags, or even charging at home. It's not as hard as opting out from cars and the roads, which kill dozens every week in the UK alone.

LiPos or Li-Ion?

LiPo, Li-Ion (not the LiPo variety, LiPo is also Li-Ion) is also dangerous but much less so from my own personal experience.

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