Battery OEM FORD or OEM Volvo

Even in the colder weather now, I'd be getting 400+ km on a full charge in my BEV (Mustang Mach e). But I only charge once a week (Fri night), to 80% to help with battery life; costs about $3 per week to get an extra 200-300km.

Always read your manual/mfr suggestions for battery charging and longevity.

For Li-ion you generally should charge no more than 80% (some mfg hide 10% via software like Ford, so you charge to 90%). Also, limit fee cycling these types too, regularly you should DC to about 50% max. Occasionally deep cycling and full charging is fine. Should limit DCFC also.

I got 14 years out of the battery in my Volvo.

Well my Volvo dealership wanted $400 for a battery so yeah... It's the small things that cost the most at dealerships, maybe as a way to lessen to cost of bigger jobs so you're not paying tens of thousands for a major job.

Both of mine were defective. Ford replaced them.