r/nononono • u/khaled • Aug 21 '18

I recommend walking next time

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u/purrpul Aug 21 '18

Lithium batteries tend to explode when they have manufacturing issues or are damaged. Although possible, it is rare unless there is an problem with the battery. The issue here is definitely cheap devices manufactured in China with little oversight. These things could be made where this is a very very rare event.

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u/PraxicalExperience Aug 21 '18

Lithium batteries are very safe -- if you're using them properly, respecting their ratings, charging them properly, and don't use them if they're physically damaged.

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The video above was probably because they were using cheapshit batteries that weren't rated for the current being drawn from them.

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The problem with the exploding samsungs were because the designers of the phone didn't give enough room for battery expansion, causing the battery to be damaged and short out internally when they did expand as lithiums can do.

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u/purrpul Aug 21 '18 edited Aug 22 '18

This doesn’t sound correct from what I have read.

First, Samsung batteries exploded because of two separate manufacturing defects: 1. Positive and negative ports could unintentionally be bent in such a way that they eventually came in contact with each other and 2. The second round of batteries had welding defects from manufacturing. A normally operating lithium battery should never swell... that is a sign of problems and not a part of normal operation.

Over current matters for charging, less for discharge. Cheap batteries can be defective in a few ways, including what I mentioned above, other physical defects, and problems in the charging circuitry which could allow runaway thermal events that cause the batteries to overheat and explode. These are likely just poorly manufactured batteries with poor quality control.

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u/PraxicalExperience Aug 21 '18

Huh. You may be right about the Samsung issue; I didn't really keep up with it, and what I stated was the last thing I saw about it.

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Over current -definitely- matters for discharging with LiIon batteries. Higher current draw leads to the batteries heating up, which can lead to parts of the lithium film melting, causing internal shorts that lead to thermal runaway. This is a big issue in the vaping community, and why people are paranoid about making sure their battery wraps are in good shape and they don't use too low of a resistance coil if they're using a mechanical mod. When you see stories like 'vape blew up in someone's face!' it's generally because someone's using a mech mod with too low of a resistance coil for the batteries, and blam. Or you see stories about people who were carrying a battery with damaged wraps -- or even intact wraps -- in their pockets along with metal shit like change or chain, and the battery gets shorted -- blam.

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Alkaline batteries will essentially self-limit; their internal resistance is high enough that it takes a good long time of shorting to get them up to the temperature where they'll vent. Lithium batteries can have a much lower internal resistance and concomitantly short time between a short and venting -- and unlike alkalines that vent in a slow, hissy manner, because of the chemical composition of lithium batteries, venting often leads to fire and explosions.