As long as 5V is supplied from either the USB or the 5V pin, I don’t think it’s possible to distinguish whether the battery is fully charged at 4.2V or if the charging IC is simply outputting 4.2V.
As long as 5V is supplied from either the USB or the 5V pin, I don’t think it’s possible to distinguish whether the battery is fully charged at 4.2V or if the charging IC is simply outputting 4.2V.