iphone question [View all]

iphone 5 something ...

i've recently noticed a strange behavior with my phone ...
on mondays only, each monday for the last month+
i always plug my fone to charge overnite, and 6 days a week awaken to find 100% charge status, but on monday it always says 78%...
always and will not upcharge beyond 78% no matter how long plugged
in...
i'll unplug and it will drain down normally, plug it up again and it's not charging
(the battery is newish, maybe 6 months old)
the 1st time it happened, i was literally getting in the car to take it in to have it diagnosed by the techs who installed the battery, and plugged it into my car charger and it said 100% immediately... so forgot about it,
figured it was a glitch... same thing a week ltr,
no big deal, car charge same result, next week again,
and i realized it always monday, my day off... and again today...
so as it's immediately remedied with the car charger i don't think it's a real big
deal but has anyone else seen this behavior?

tia
✌🏼