I actually did have a laptop battery fail recently -- it swelled and the only reason i realized was the charging light switched from steady to blinking rapidly -- something it usually does when the battery voltage is critically low.

Old laptops don't always come with good battery charging software. Ideally you could set the battery to UPS mode and have it sit to 50%.

Funny enough there is a little Bluetooth dongle that can add this capability to usb-c laptops, but the development is now vibe coded and the developer has gone full AI and the quality of the software and customer support has taken a nosedive.