On Wed, 09 Jun 2021 17:25:55 -0400, micky
wrote:

How come my Sandisk Clip Sport says one cannot ovrcharge the battery,
but none of my smartphones have ever said that?

It's not a smart phone and deals only with one Li-Ion cell battery.
Protection electronics and charge limiters for that purpose are
commodities. I've never had a small MP3 player with battery issues.

They're claiming something that all previous competition took
for granted, to increase meaningless advertizing content.

Your smart phone has a more advanced and more complicated
battery. New developments or manufacturing changes will have
issues without a strict discipline that is often not present
in that competitive arena.

RL