This happened at a very inopportune time so apologies for the text being a bit bad.
background: framework laptop 13 with 7640 u running fedora 40. ran great for a few months.
issue: played some games on battery power. battery health went from mid 90's to 43. i know playing on battery is bad for it but that is more what i'd expect if I took a hammer to it.
what i've tried: rebooted, cleared upower history, removed 90% charge limit in bios then shut down and charged.
Any thoughts would be appreciated.
Edit: I ran it out of battery while on the bios screen then charged it to full before powering it on. Battery health is now showing 91%. I'll see if it lasts, but I'm glad I didn't just go out and buy a battery without troubleshooting first.
Sounds like one of the cells has died; fully agree that it's best to replace the battery (given its 7th gen, I doubt it's still under warranty).
Alternatively, if you like tinkering with stuff just for the sake of it, you can replace the offending cell (often slightly expanded compared to the rest of them), or all 3/4 of them: in my experience, replacing only the dead one results in another one dying relatively soon after, but may still be a viable temporary solution if you're short on money or have something of similar size lying around. Also, if you decide it sounds fun, be sure to look up how-to's, as just disconnecting a cell will make most BMSes lock themselves + possibly burn the fuse, and you probably don't want to play the game of "is this BMS unlockable without paying 100500 kilomoney for specialized equipment"
It is under warranty, but there's a slightly higher capacity one I might get instead. Thanks for the explanation for how it could have actually failed.