Since more and more questions are being received about how to properly charge a phone battery, I decided to write this article. If the admins choose, they can pin it as important. I’m writing this as a hardware engineer with over 40 years of experience. I’ll include some theory followed by practical examples.
The percentage displayed by your phone corresponds to a specific battery voltage, which differs by manufacturer. For example, 100% charge typically means 3.6-3.8V, while 0% corresponds to 1.5-1.8V. However, the voltage never truly reaches 0 due to the battery management system (BMS) and the phone’s internal controller. These systems ensure the battery neither overcharges nor discharges to zero, meaning how and when you charge doesn’t matter as much as people think.
Many believe that charging the battery to 80% and not letting it drop below 20% helps extend battery life, but this is a misconception. It’s like waiting for a washing machine to stop spinning to prevent damage—it’s unnecessary. By following this method, you limit the full potential of your battery, missing out on 40% of its capacity, which could provide a full day of use. This behavior turns you into a slave to your phone, which was designed to serve you.
What is good practice? When you buy a new phone, it typically comes with some initial charge. Let the battery drain to 0%, then fully charge it to 100%. Doing this 4-5 times helps calibrate the battery, allowing you to use its full capacity in the future. Additionally, once or twice a month, it’s beneficial to let your phone completely discharge and charge it fully without using it. While it’s fine to use your phone while charging, most phones draw power directly from the charger when plugged in, leaving the battery as it is.
Regarding fast and slow chargers, fast chargers provide high voltage and amperage initially to quickly charge the battery. There’s no harm in using them, as the phone’s controller regulates the charging process. Slow chargers, usually 5 volts and 1-2 amps, deliver a steady charge without spikes. After years of experience, I haven’t noticed much difference in battery life between fast and slow charging methods.
Different manufacturers handle charging differently. For instance, Huawei devices continue charging even after reaching 100%, while Apple phones behave similarly. With some other manufacturers, the charge stops immediately at 100%, and the battery may drop to 99% shortly after unplugging. This difference has no impact on the battery’s life.
Years ago, I bought a second-hand Huawei P10 from someone who had used the 20-80% charging method for 1.5 years. When I started using it, I noticed the battery drained slowly from 100% to 80%, but from 80% to 20%, it dropped quickly. I had to perform 10 full charge-discharge cycles to recalibrate the battery. This situation shows how limiting battery usage to a certain range can actually shorten its lifespan.
In conclusion, use your phone as you see fit. Manufacturers have designed the devices for your convenience, so don’t worry about these charging myths. The phone is there to serve you, not the other way around.
