Is it bad to let a S9+'s battery run down to 0%?

[Kaiju1998]

Does doing this constantly cause the battery life to shorten? Also, what percentage should I charge my S9+ at?

 

[Rukbat]

It's bad to do that to any lithium battery, cellphones, drills, lawn mowers, etc. 40% to 95% is about the best range for longest life. Running the battery down until the phone shuts off every time can kill the battery in a month or two (and it's no longer a matter of popping the back cover off and replacing the battery for $10). Charging to 100% all the time (if the charger doesn't shut off when the battery is fully charged, for some reason) can vent electrolyte.

Use something like GSam Battery Monitor to give you alarms during use and charge.