I've been using a company iPhone for quite some time now, and I found it to be much better than my Android personal phone, so I decided to buy a 256 Gb iPhone XS. I like it much better than my Samsung, except for the battery - even if it's brand new, it runs out of juice pretty quickly (it may also be that I'm so happy with my purchase, that I end up overusing it - the UX is much better :-) What's the recommended routine for an iPhone? Should I charge it as soon as battery gets down to 20%? Sooner? Later?
Apple has a guide on how to maximize the performance of your battery.
Here are some of the key points:
- Avoid extreme temperatures
- Remove certain cases during charging(may cause excessive heat)
- Store the device half-charged when storing long-term without usage
- You may also want to check battery settings for what apps are using your battery and maybe disable background app refresh/location services for those apps
- Make sure your display brightness isn't too high and enable auto-brightness if you want
Additional tip(not included in article): Keeping your device between 20%-80% helps your battery last longer. The website says keeping your device up to date also helps, but in many cases updating older devices reduces battery life.(the one exception to this is iOS 12 which actually improved performance and battery life)
My personal answer: Charge whenever you can!
Lithium ion batteries basically age based on the pace at which you use them. Whenever the battery goes down, then back up, whether it's 10% or 90%, it ages the amount it went up and down. So it shouldn't matter if you drain it 10% or 50% before charging, any time you're actually using your phone, it is draining and aging the battery.
So: Basically just charge it whenever you have a chance so that you are keeping it as full as possible. This will be convenient for you and shouldn't have any effect on the battery compared to letting it get really low before filling it again.
What about leaving it plugged in?
I honestly don't know anymore. Logically, the facts above about lithium ion batteries imply that keeping it plugged in is the best solution, since it isn't going up and down, just staying at 100%, but I'm not sure if this is practically true or not. Apple makes no mention of whether to keep it plugged in or not in the document linked below, which is annoying, since IMHO it's the biggest question there is.
I personally try to plug it in whenever I can, but for practical reasons I rarely keep it plugged in while using it, which is the main time it's draining anyway.
The answers on this older question on AskDifferent about "overcharging" imply that there's no reason to think leaving it plugged in is bad for the phone, but there's not much hard evidence there.
I think the most important thing to keep in mind is: Don't keep it plugged in if what you're doing is making it hot. Heat is the biggest enemy of battery performance in short and long term (as described below), so mixing charging which heats up the phone with intense activities that heat up the phone (e.g. gaming) is probably a bad solution.
Leave the screen off unless you need it.
Remember that the screen is the biggest drain on the battery. It can do non-screen things all day, but any time the OLED is lit up the battery is draining like crazy, so if you find yourself staring at the podcasts app, opening the phone just to admire it's beauty etc. then stop doing that and your battery will last longer each day (and stay more full over the years, since anything that avoids the battery going down in the short term also inherently makes stronger in the long term).
Apple's answer: Vague!
Apple has a detailed article that covers this in detail, here's some quotes:
“Battery life” is the amount of time your device runs before it needs to be recharged. “Battery lifespan” is the amount of time your battery lasts until it needs to be replaced. Maximize both and you’ll get the most out of your Apple devices, no matter which ones you own.
Your device is designed to perform well in a wide range of ambient temperatures, with 62° to 72° F (16° to 22° C) as the ideal comfort zone. It’s especially important to avoid exposing your device to ambient temperatures higher than 95° F (35° C), 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.
iPhone, iPad, iPod, and Apple Watch work best at 32° to 95° F (0° to 35° C) ambient temperatures. Storage temperature: -4° to 113° F (-20° to 45° C).
Brightness settings are something to consider:
There are two simple ways you can preserve battery life — no matter how you use your device: adjust your screen brightness and use Wi-Fi.
Dim the screen or turn on Auto-Brightness to extend battery life.
- To dim, open Control Center and drag the Brightness slider to the bottom.
- Auto-Brightness adjusts your screen to lighting conditions automatically. To activate it, go to Settings > General > Accessibility > Display Accommodations and set Auto-Brightness to On.
When you use your device to access data, a Wi-Fi connection uses less power than a cellular network — so keep Wi-Fi on at all times. To turn on Wi-Fi, go to Settings > Wi-Fi to access a Wi-Fi network.
Remember to engage low power mode when it you forget and it gets really low!
Enable Low Power Mode.
Introduced with iOS 9, Low Power Mode is an easy way to extend the battery life of your iPhone when it starts to get low. Your iPhone lets you know when your battery level goes down to 20%, and again at 10%, and lets you turn on Low Power Mode with one tap. Or you can enable it by going to Settings > Battery. Low Power Mode reduces display brightness, optimizes device performance, and minimizes system animations.