For lithium batteries (phone batteries) it’s actually more important than draining to 0. Many studies indicate that the average phone battery should last several thousand cycles while only losing 5-10% of total capacity provided it is never charged above 80%. Minimum % (even down to 0%) and charge rate below 70% is also unrestricted.
The tl;dr is that everytime you charge to 100% is the same as 50-100 charges to 80%. Draining a lithium chemistry battery to 0 isn’t an issue as long as you don’t leave it in a discharged state (immediately charging).
For lithium batteries (phone batteries) it’s actually more important than draining to 0. Many studies indicate that the average phone battery should last several thousand cycles while only losing 5-10% of total capacity provided it is never charged above 80%. Minimum % (even down to 0%) and charge rate below 70% is also unrestricted.
The tl;dr is that everytime you charge to 100% is the same as 50-100 charges to 80%. Draining a lithium chemistry battery to 0 isn’t an issue as long as you don’t leave it in a discharged state (immediately charging).