Everything You Need to Know About iPhone Batteries

In Apple’s iPhones, it is fair to say that the battery is a bit of a mystery box. Unlike some of its competitors, it’s non-removable, so you have to trust that what you are getting is actually good. When shopping for a refurbished iPhone, a good battery is just as important as a sleek appearance.

Fortunately, you don’t have to stay in the dark. In this guide, we will answer some commonly asked questions regarding iPhone batteries, from understanding good capacity levels to the typical performance of an iPhone battery across different models.

Everything mentioned in this guide is applicable to all current and recent models of Apple smartphones. Where necessary, we’ve pointed out how different models function when it comes to their batteries. Generally speaking, though, this comprehensive iPhone battery guide will be helpful regardless of whether you’re looking to purchase an iPhone 13, or iPhone 17.

Understanding iPhone Battery Capacity

With the release of iOS 11.3 in 2018, Apple introduced a new feature that can tell you quite a lot about the capacity and function of your battery: Battery Health. It describes exactly how long your iPhone should last between charge cycles, on a scale of 0% to 100%.

Your phone’s maximum battery capacity goes down over time. New iPhones typically come with a 100% capacity, but charge cycles and potential damage (like exposing your phone to extreme temperatures) reduce the capacity.

As your battery’s health declines, so does its ability to deliver maximum performance.

What iPhone Battery Capacity is Considered Optimal Condition?

You might think that because your iPhone’s maximum capacity begins at 100%, it’s the only condition that can be considered optimal. However, that’s not quite true. Apple considers any iPhone with a battery capacity of 80% or above to be in optimal condition.

Apple designs its batteries to retain 80% of their original capacity at 500 complete charge cycles (iPhone 14 and earlier) or 1,000 (iPhone 15 models) under ideal conditions, and its one-year warranty includes service coverage for a defective battery. It’s not unusual to see iPhones that, after one year, still have a battery capacity of 95% or above.

How to Check the Battery Status of Your iPhone

On any iPhone with iOS 11.3 or later installed, you can find your battery capacity by going to Settings > Battery > Battery Health. It’s important to note that this feature is only available for the iPhone 6 and any models that came after it.

In your Battery Health screen, you’ll also see an important secondary metric: Peak Performance Capability. Because of the above-mentioned nuance, this screen might actually be more important than capacity.

If your battery runs optimally to support all of your apps, you will see a simple message that your phone is operating at normal peak performance. If your battery is worn and potentially in need of replacement, you will see a warning that it is degraded and should be replaced.

If you see the warning message, your phone will still function, but the time between charge cycles will be significantly shorter. The message only appears when your battery capacity is at 79% or below.

How to Extend Your iPhone’s Battery Life and Performance

Apple has tried to extend the battery life of their phones through something called performance throttling, or performance management, which caused some controversy a few years ago. Performance management throttles your phone’s performance on your behalf to keep the iPhone running and conserve battery. On the models that offer the option you can turn it off manually, but then your iPhone may shut down unexpectedly when the battery cannot supply the power it needs.

Instead, it makes sense to take these few simple steps that can extend your phone’s battery life, courtesy of Apple:

• Stay on the latest iOS upgrade. Every major upgrade comes with new features to preserve and extend battery life.
• Try to keep your phone in temperatures between 16 and 22 degrees celsius on average. Anything above or beyond might be damaging to your lithium battery.
• Avoid excess heat when charging. Some cases or surfaces can cause your phone to heat up, which can damage the battery. Check it while it is charging to make sure it stays cool.
• Store your phone half-charged. Emptying the battery completely could cause it to fall into deep discharge, which will cause significant damage. The drainage from a full battery could have the same effect.
• Turn on auto-brightness. The brightest screen settings tend to drain your battery quickly, which forces you to go through charge cycles quickly and lose battery health.
• Check your background activity in Settings > General > Background Refresh. Too many apps running in the background will drain your battery.

How iPhone Batteries Perform Based on Individual Models

When researching used iPhones, battery life and performance are probably among your top considerations. You can look at factors like the processing speed or RAM, but how much does that really tell you about the phone’s actual user experience?

A number you can compare across models is the video playback time that Apple publishes in the tech specs of each iPhone. These are Apple’s own figures, from its tests, for the models most people buy today:

• iPhone 17 Pro Max – up to 39 hours
• iPhone 17 Pro – up to 33 hours
• iPhone 17 – up to 30 hours
• iPhone Air – up to 27 hours
• iPhone 17e – up to 26 hours
• iPhone 16 Pro – up to 27 hours
• iPhone 16 – up to 22 hours
• iPhone 15 – up to 20 hours
• iPhone 14 – up to 20 hours
• iPhone 13 – up to 19 hours

These figures are for video playback on a battery that is still at its original capacity. In daily use the time between charges depends on how you use the phone and on the battery’s health.

The bottom line is that newer models, regardless of whether their capacity is below 100%, tend to have longer battery life than their older counterparts and will be useful for longer as a result.

What Can You Expect From a Swappie Refurbished iPhone?

At Swappie, every refurbished iPhone with a Standard battery has a battery health of at least 86%, meaning that it will work and perform like a new iPhone. If you want the best, a New battery with 100% battery health is available as an option. You don’t have to worry about replacing the battery to get the performance you want. Whatever iPhone you choose, it is worth checking its battery health before committing to a purchase.

Especially in older models, even a perfectly functioning battery will not be as effective as it would be in a newer model. As shown above, Apple rates an iPhone 13 at up to 19 hours of video playback, against up to 39 hours for the iPhone 17 Pro Max. Keeping your expectations in line with reality can help you make a purchase that works well for both you and your phone.

So now that you have read our complete guide to iPhone batteries, we hope that you feel more confident with your knowledge. If you’re interested in checking out Swappie’s selection of refurbished iPhones, you can find them here.