And you don't have to turn it off to charge it; in fact, you shouldn't. And you can leave it plugged in while using it if you want to. The Best Practice, however, is to charge the phone overnight, every night. As it stops automatically at 100% you can't overcharge it doing this.
Charging overnight is not a danger to your battery in and of itself. However, temperature is a real concern. One of the most damaging things your battery can experience is extreme heat or extreme cold. Apple has publicly stated that temperatures above 35 degrees Celsius can cause permanent damage to battery life.
You can't overcharge an iPhone battery and the best way to manage your battery is to turn on Optimized Battery Charging and plug your phone in to charge when you go to bed at night and leave in plugged in all night every night.
It's especially important to avoid exposing your device to ambient temperatures higher than 35° C (95° F), which can permanently damage battery capacity. That is, your battery won't power your device as long on a given charge. Charging the device in high ambient temperatures can damage it further.
The two things that cause the most battery drain in your iPhone are its screen and cellular service. Obviously, you know when you're actively using your phone, but your iPhone is often performing tasks in the background and even lighting up your screen without you noticing.
The batteries in iPhones aren't like old rechargeable. They don't develop a memory. Charge it whenever you like and to whatever capacity you like. The only thing that's "bad" for it is allowing it to discharge completely.
Modern smartphones have optimized batteries that will stop drawing power once they reach 100 percent. However, when you leave it on the charger, the phone will inevitably lose a little bit of power as it sits there because that's just what batteries do.
Lithium-ion batteries have a shelf life, and each charge cycle reduces the maximum capacity of the battery. If you constantly charge your iPhone to 100% and leave it plugged in for an extended duration, you are reducing the lifespan of the battery.
“Do not leave your phone connected to the charger for long periods of time or overnight." Huawei says, "Keeping your battery level as close to the middle (30% to 70%) as possible can effectively prolong the battery life." The official word is to keep your phone charged – but not fully charged.
Therefore, we recommend the following: Do not fully charge or fully discharge your device's battery — charge it to around 50 percent. If you store a device when its battery is fully discharged, the battery could fall into a deep discharge state, which renders it incapable of holding a charge.
Maintain good battery health
It is always recommended by experts to start charging your iPhone when it hits 25 percent. Similarly, only charging the battery up to 85 percent will help the iPhone's battery to maintain good battery health and deliver extended battery life.
Is it bad to charge your phone multiple times a day? No. Lithium-ion batteries like to be charged in short spurts, so plugging in for five-percent here and 10-percent there is not only fine, but advisable.
Charging your phone overnight occasionally probably won't make a noticeable difference in the battery life for years to come, but if you do it every night consistently, you will probably notice your battery performance degrading over time.
Put simply, you can safely charge your devices overnight without having to worry about damaging their internals. Modern electronics automatically stop pulling current once their batteries reach 100% charge.
The Best Practice, however, is to charge the phone overnight, every night. As it stops automatically at 100% you can't overcharge it doing this.
Since the iPhone's release, there has been a lot of speculation about the best way to care for an iPhone's battery, including the rumour that it needs a full charge before you should unplug it. This is actually false and is based on old technologies that were never a part of the iPhone's design.
To extend the lifespan of your battery, if the battery gets too warm, software might limit charging above 80 percent. Your iPhone will charge again when the temperature drops.
The short answer is no! It is not necessarily bad to charge your phone multiple times per day. In fact, it is better to charge your phone when it reaches a low battery level rather than letting it run all the way to empty.
To extend the lifespan of your battery, if the battery gets too warm, software might limit charging above 80 percent. Your iPhone will charge again when the temperature drops.
Avoid situations where your phone can overheat, especially when your battery is fully charged. Your battery drains much faster when it's hot, even when not in use. This kind of drain can damage your battery. You don't need to teach your phone the battery's capacity by going from full charge to zero, or zero to full.
A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles when operating under normal conditions. The one-year warranty includes service coverage for a defective battery.
Shomes recommends charging your iPhone as it needs it. If you go to sleep and it has a 40 or 50 percent charge, leave it. Then charge it some time during the next day when it gets into the red. That way, the battery won't be stressed, and its health will last way longer than it will when overnight charging.
Apple says that an iPhone battery “is designed to retain up to 80 percent of its original capacity at 500 complete charge cycles when operating under normal conditions,” but regular overnight charging accelerates that degradation.