Extend battery life: charge from 40% to 80% or from 30% to 70% ?

Hi, when I want to extend my phone's battery life, how should I charge it ? I have seen multiple different recommendations how to charge a battery.

Is better to start charging from 40% and stop at 80% charge level ?

Or should I start charging at 30% and stop at 70% ?

To extend lifespan of lithium-ion battery, it is recommended to not fully charge it. Lithium-ion batteries are usually used in phones and laptops. Charging to 100% level stresses them.

There are multiple recommendations how to charge Li-Ion battery. Probably the most popular is so called 40-80 rule, according to which is recommended to keep the charge level close to 40% - 80%. Other popular battery charging rules are 20-80 and 20-90.

But manufacturers have their own recommendations, how to charge lithium-ion batteries:

Samsung recommends charge battery to less than 100%, optimally to 80% - 85%
HP recommends charge battery to 85% - 90%
Apple recommends charge battery to around 80%
Huawei recommends 30-70 rule

To stop charging at a certain charge level, you can use some of the battery charging apps.

Li-ion batteries don't like full charge and full discharge. To prolong Lithium-ion battery life, it is recommended to not fully charge the battery, but also you should avoid its full discharge for a longer periods of time.