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Originally Posted by Migrant_Coconut
Any reason why we have overheating bike/scooter/EV batteries, but not overheating laptop/phone batteries (except on a plane)? That might be something to look into.
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Overheating laptop batteries were a problem for Dell and Sony in the early 2000's. There was recalls and a rather major overhaul of the laptop battery industry. Once they figured out how to keep the cells stable through more advanced charge controllers and thermal monitoring the problem has mostly gone away and became less of an issue as lower power and higher performance laptops and portable devices no longer needed a metric ton of lithium cells to get 2-4 hours of run time. There was also the additional of internal one-shot fuses for short-circuit protection or vents so that in the event of a cell gassing up it blows a rupture disc and vents out one end of the cell, rather than becoming a bomb.
Lithium technology is kind of a dark magic compared to the old Ni-CD and Ni-MH batteries everything used.
-If you let it fully discharge the cells can become chemically unstable.
-If they are allowed to sit for too long(years), they become chemically unstable. This occasionally causes storage unit fires due to forgotten electronics such as an old phone.
-If they are charged too fast they thermally run away.
-If you discharge them too fast, they thermally run away.
-If you let them get too hot from external factors they thermally run away.
-If the casing or pillow is ruptured, the lithium alloy can react with the air much like Sodium and burst into flames and of course...
-if they are mechanically allowed to short they go into a deep discharge state, become chemically unstable and usually burst into flames.
Lithium-Polymer cells (they look like flat silver pillows) are famous for when they fail or go bad they swell up and can force apart whatever device they are in. The tech world calls them "spicy pillows". Apple products are famous for this.
Why do we use it? There's nothing else commercially viable that packs more potential energy per square inch. Lithium can store a
LOT of energy. It's also extremely cheap.
Most E-bike batteries are just lots of 18650 or equivalent type batteries paralleled in series in a sealed capsule. If you drop a freshly exhausted pack into a charger and the pack isn't intelligent enough to detect it's "hot" and start the charge at a reduced rate until it thermally stabilizes, that will start a runaway. If the charger is one of the cheap fast chargers that starts the charge at a high current rather than reading the pack's battery controller again, the cells may simply overheat, burst and the bonfire begins.
Another is that third party or aftermarket lithium batteries omit a lot of the battery and charge control to bring the cost down. It's surprising how when you spend $9000 for an eBike you look for cheap options when the time comes to replace the $400 pack. Both Apple and iRobot/Roomba put DRM into their charge controllers specifically because cheap replacement batteries were causing fires. (TBH, it's funny watching videos of a Roomba after an hour of cleaning the house returning back to its home, making a cheery sound that it's home and docked and then a few minutes later it bursts into flames)
Back in the day, Dell laptops actually snitched on the AC adapter if either it wasn't genuine or you tried using a lower wattage AC adapter with a higher-end model laptop.
Lithium-ion is one of things that has to be both handled and stored carefully or it will burn your life down for no reason.
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This is really an apples to oranges comparison from someone who is detached from the reality of most people in Vancouver.
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