ThinkPad batteries are lithium-ion, so capacity loss over time is normal. But my brand-new replacement battery dropped to 97% in a month, and it won’t charge past 99%. That’s definitely fucked up. I remember there used to be a ThinkPad Windows tool for recalibrating the battery — drain it completely, charge it back up, let it re-estimate capacity. Except I’m on Linux. And after I dug up a Windows To Go drive and booted into Windows, that ThinkPad tool was gone anyway, so I had no idea how to calibrate. Good thing TLP exists on Linux and can recalibrate the battery. One command, that’s it.