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.
However, every battery has its own charging cycles. And your battery capacity will also reduce as the charging cycles increase. But you can follow some tips to maximize the battery performance and help expand 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.
By the way, you can often check your iPhone battery health. For iPhone 6 and later, iOS 11.3 and later add new features to show battery health and recommend if a battery needs to be replaced. These can be found in Settings > Battery > Battery Health. If the battery health is lower than 80%, it means that you need to change a new iPhone battery. If the battery health is higher than 80%, you can still use your iPhone as normal. But if the battery still drains too fast, you can read on this tutorial to fix this problem: 12 Methods to Fix Fast Draining iPhone Battery
