I believe the research would suggest 80% doesn't really make an especially good target. Its mostly a linear relationship between state of charge and speed of battery aging, other than a step change around 50-70% depending on the chemistry.
source (one of many): https://iopscience.iop.org/article/10.1149/2.0411609jes/pdf
I keep my EV charged to just 50% most days for this reason, get below that step change.
