Comment by 0_____0

Bigger, fewer, more chill cells, fairly robust trenchcoat.

(IIRC, these packs are 16 100ah LiFePO4 cells in a steel case w/ built-in fuse, breaker, and BMS that monitors individual cell health and pack temperature, w/ automatic cut-off if any of that goes out of spec. The weakness is primarily the MOSFETs on the BMS potentially failing shorted. Fortunately, they've added some sort of additional fire suppression beyond just "steel case" in recent-ish versions of these packs)

I can't see what the construction looks like but the mention of 'fire arrestors' gives me a lot of hope. If you haven't designed a battery that can take a cell runaway safely, you haven't done the work, and clearly they've done at least that much.

For a highly engineered battery like a premium EV, there are coolant channels, temp monitoring, voltage monitoring, etc.

Soldering some connectors onto some random cells and knowing they shouldn't go over 4.2v is one thing, but measuring cell health via internal resistance, programming a controller to do temp shutoff and wiring up temp sensors, keeping cells balanced, is a lot of extra work, but critical if you at all care about not potentially burning down wherever they're stored.

Keeping the cells small and just using a hundred of them in parallel (and a hundred of these parallel packs in series to get up to the hundreds of volts needed), thus using ~10,000 cells, in EV batteries limits the maximum damage from one cell going worst-case, assuming your enclosure can contain it.

That being said, it seems there is a slow movement towards larger cells, from 18650 to 26650 or similar. But each cell on its own is still a dumb can of chemicals ready to go boom if you mistreat it.

I used to joke with my buddy back when he first got his Tesla that we were driving around on "over 7000 vape batteries!", as that was the fad at the time and where most normal consumers recognized them.

There's some optimization that happens in the chemistry and construction details for specific uses.

Also with bigger packs inter-cell consistency is really important (good cell integrators will test and bin them by ESR even if they're from the same lot, and using a really reliable cell mfg/vendor is critical because you're selling expensive systems with a number of failure points that scales with the number of cells and you want their process development to be super mature.

There's a lot of risk in creativity when you're selling crap to the public at scale. Way better to just use what everyone else is using.