modern devices often keep the battery at 80% level if charged for a long time, for this reason. (they say "to extend battery life" in notifications, and that mi

modern devices often keep the battery at 80% level if charged for a long time, for this reason. (they say "to extend battery life" in notifications, and that might also be a side effect, but AFAIK the primary reason is to reduce the probability of bulging. But many/most of these older devices discuss, do not - and my personal anecdote is that of the tens of phones+laptops I have owned myself and managed for family through the years - there were 4 cases of bulging: 3 were constantly-charging devices (as in, 3-5 years with hardly any time not charging), and one that was dropped from height and bulged immediately.