From “Engineering Explained.” He says that as you charge/discharge, the random orientation of microcrystalline structure in the battery combined with expansion/contraction due to Lithium migration results in forming cracks in the particles, which then results in reduced battery capacity. I’ve been letting my battery get down to 50% or so before bothering to charge back up to 80%, I may default to 70% and charge after every trip instead. (For a Volvo with NMC chemistry I’m not sure if I have “high nickel content” and would benefit form staying below 75% or not.)
There is a difference between requirements and best practices though. There are some things that rarely impact me one way or another, so I’m happy to do it as feasible.
Like, setting an 80% charge limit. I’m in no way required to do that, but I typically drive 50 miles a day or less. That’s about 20% of my battery capacity. I plug into a charging setup every night that can bring my battery from 0-100% while I sleep. So I really don’t care if that 20% capacity usage means I go from 100-80% or 80-60%. For those days, I’m happy to set an 80% charge limit. I’m not required to, and when I have a day of over 100 miles planned (doesn’t usually happen spontaneously) I’ll bump it up to 100% because my car works for me and it’s designed to do that if needed.