new fixit battery bought

Just got new battery delivered from iFixIt, and battery installed in my MBA 13’

I charged it up, left it for 2 hours, then let it drain till power of, however before Activity Monitor only shows 5 hours on full charge..

I then set SMC/PRAM, and it change to 15 hours…. but then I rebooted and gone back to 5. So I think didn’t “wait additional 5 hours" after power down” I didn’t do…

Any suggestions ?

FYI… why five hours? What is the reason for that part ? eg. does it do something?

i.e Apple devices are the only thing you see when “calibrating” you never see this with non-apple products, at least there is no “calibrate your drill”

umm… eve when charged *led is green” the full charge remaing and current change is always different.. unless i leave not longer

Activity monitor is now showing 6 hours when “idle” so its not an app

I created under new account, and Activity monitor in new account shows same thing.. Anything else as its clearly not app related..

At this point i’m thinking of doing a clean install and see what happens then.. It seems SMC/PRAM reset worked only briefly as above. This is the current one on full charge,