I’m almost exclusively using a 7kw charger (free use at the office), so my battery gets charged to 100% over about 5 hours during the day – car is 7 months old and done about 6.3k miles.
Think I’ve used a fast charger (22kw) about 5 times and only charged to 80% using that.
My thinking is the 7kw is a slow charge so the battery doesn’t get as warm so the degradation isn’t the same and is far slower.
Selfishly, the car is a lease so will be handed back after 3 years, so I’m not losing sleep over it, but at the same time, I’m not wanting to deliberately ruin the battery.