Below the 3.0 volt limit will reduce usable cycle count by 30-80% Everytime the cell drops that low. Charging over 4.1 will reduce usable cycle count as well.

Example # of usable cycles if you stop discharge at 3.2 and stop charging at 4.0 for modern lipos can be 5000-10000 cycles.

Charging to 4.3 every cycle (phone batteries are rated to 4.3 not 4.2… it’s why they have the larger than expected wh capacity numbers) will reduce that to 500.

Discharge it to 2.5 and you will get 10-50 cycles.

For those who are just looking at the SD or their phones… Most devices report 0% at 3 or 3.1v and 100% at 4.3 or 4.2 volts… So basically discharging to 0% doesn’t matter… It’s the charging to 100% that matters to most people.

If you charge to 100% you will get about 500 charges (it doesn’t matter what the % is you start at is… 90% -> 100% is the same one cycle as 20% -> 100%). That’s about two years of use for most people before your battery starts to suffer and you will see noticable decrease in battery life.

If you charge to 70% you will get about 10 years before you will see a drop in battery life. 80% will get you about 6-8 years.