Hi all , just wondered if this or similar had happened to anyone else, my S10 got down to 5% battery left ( I know I shouldn't let it get so low ) and at 5% it just turned itself off and as I tried to turn it back on it had 0% in it , so basically it went from 5% to 0% straight away !!
Basically every so often the battery is misread, when the phone goes completely flat it will recalibrate it so now it will show the true reading. From time to time this happens and its nothing to worry about, basically your battery was empty which is why it turned off but now it shouldn't happen again for a while. I run mine flat once every 6 weeks to keep the reading accurate.
To enhance battery performance best not to completely discharge . 20% is regarded as the optimum but would say not to let it drop much below 15% anyway. Think battery does discharge rapidly once around 5%.
There is a school of thought suggesting battery should be completely discharged periodically bit I do not think that is particularly desirable.