Though in Many Handsets Auto Power Cut off System is there, which works when phone got Fully Charged and it stops further unnecessary of power supply...
And further there might be the Led Colour light notification, which changes from Red to Green when fully charged.. Also we have Battery Percentage Status to give idea about charging status....
But we only came to know about Full Charging Status through these methods only by Seeing it and we need to check many times in-between that phone got Charged or not....
So what if we got a Buzzer Sound or a Specific tune to get notified as soon as battery status goes 100% or fully charged, I am getting it on my Note9 but don't know is it because of "Quick heal total Security" or because of any other app or it is with Note9 system app itself...But I like it, Since I have observed that even after getting 100% battery status while charging it takes some more time to get Led from Red to Green but this Buzzer Sounds immediately as soon as it got 100% bench mark of charging battery status...
Not So with S10 of my Friend and this difference he observed when we put Both Note9 & S10 for charging and my Note9 sounds as soon as it got Fully charged but not his and infact his phone was got charged prior to mine...We searched if any such setting is there or not ?? But we won't get anything..If anybody have any idea if it is system Setting or not?? If yes, then where does it exists??