Battery life?

Question

How many cycles can a battery do in its life? Is it better to charge the iphone when the battery is less than 20%?

Answer 1

iPhone batteries use lithium-ion technology. Compared with older generations of battery technology, lithium-ion batteries charge faster, last longer, and have a higher power density for more battery life in a lighter package.
“Battery life” is the amount of time a device runs before it needs to be recharged. “Battery lifespan” is the amount of time a battery lasts until it needs to be replaced. One factor affecting battery life and lifespan is the mix of things you do with your device. No matter how you use it, there are ways to help. A battery’s lifespan is related to its “chemical age,” which is more than just the passage of time. It includes different factors, such as the number of charge cycles and how it was cared for.
You can follow some tips to maximize battery performance and help extend battery lifespan. For example, keep iPhone half-charged when it’s stored for the long term. Also avoid charging or leaving iPhone in hot environments, including direct sun exposure, for extended periods of time.
Read on this tutorial to learn more tips: https://all-things-about-apple.blogspot.com/2021/06/12-ways-to-fix-fast-draining-battery-on.html

Answer 2

Remember that "Battery Life" and "Battery LifeSpan", both are two different things. As you asked in the question, i would like to tell you that try your best to not drop the battery below 20% as it gradually makes the battery slow. Update to the latest softwares. Further details can be seen in the below link:

https://www.apple.com/lae/batteries/maximizing-performance/