Charge Limit or Optimized Battery Charging for iPhone?

There is lots of confusion around whether to use a Charge Limit or Optimized Battery Charging on iPhone, and which is best for battery longevity and to use. I am here to demystify it.

First off, we must understand and add a bit background to both charging habits. Charge Limits are fairly new and were introduced with iOS 18 around September 2024. This feature is only supported on the iPhone 15 and later. What the Charge Limit does is pause charging at the limit you set, which can be 80%, 85%, 90%, and 95%. If your iPhone’s charge goes below 5% of the charge limit you set, charging will resume again until it hits your limit.

Then we have Optimized Battery Charging, which has been here since the release of iOS 13 around September of 2019. Optimized Battery Charging learns from your charging habits daily overnight and waits to finish charging past 80% before you need to use it. It is on by default when you setup your iPhone. This will want to be used with charging every day, all night.

Note that there are a few requirements for Optimized Battery Charging to work. First, you must have the Charge Limit set to 100%. Second, Optimized Battery Charging takes at least 14 days to activate and learn from your habits. Third, it needs to experience 9 charges or more of 5 hours or more at a certain location. Note that it only activates when the iPhone’s intelligence determines you’ll leave it on the charger for an extended period of time, which usually is overnight. If you are ever traveling and your usage will be more variable, Optimized Battery Charging won’t enable. For that to happen a few location settings must be on.

Follow these steps:

• Go to Settings > Privacy & Security > Location Services and turn on Location Services.
• Go to Settings > Privacy & Security > Location Services > System Services and turn on System Customization.
• Go to Settings > Privacy & Security > Location Services > System Services > Significant Locations and turn on Significant Locations.

Now onto the big question of which charging habits should I use to ensure my battery lasts longer? Some people think Charge Limits are better because they don’t “overcharge” the battery, but there’s no such thing as that. Your iPhone automatically stops charging when it's full. You end up having to charge your iPhone more often which will degrade the battery faster. In addition to that caveat, your iPhone will still charge to 100% “occasionally”, which defeats the purpose of the Limit. There is no set definition of the word “occasionally”, it can be weekly or even more often. In addition, Charge Limits are believed to merely give users a way of micromanaging their battery. If it really were important and the best charging habit, Apple likely would have released it to most supported iPhone models, but they chose only the newest ones. While some have compared and claimed the Charge Limits are better, the results were mostly disappointing and didn't notice much of a difference until many years later.

Compared to Optimized Battery Charging which has been around for the longest of time for about all iPhone models. This ensures every single day you wake up with a full charged iPhone that will last the whole day. And some users think their iPhone is being overcharged and that charging overnight is not healthy for the battery, in reality it isn’t and as I stated, charging is paused until right before you take the iPhone off the charger. Through the night any power used is coming from the outlet or main source, giving your battery rest and extending the longevity of it. As a result, Optimized Battery Charging is the better option.

Users that have used the Charge Limit have also noticed downsides to it. While the battery may be sufficient enough for at home or near a charger, when outdoors using the Camera or other high-power consuming applications, it often isn't enough. And by allowing your iPhone to run this low on the battery, will actually degrade it more, as further explained below.

Furthermore, testing has been done in the wild and the results were surprising. MacRumors used the 16 Pro Max with the 80% Charge Limit for one year and ended up with 94% after 300 charge cycles. 1% per 50 charge cycles is expected for newer models, so 300/50 = 6% drop which was expected regardless of the Charge Limit or not. Guess what, another person from the article below tested the same model with Optimized Battery Charging for 1 year, and they ended up with roughly the same charge cycles, and a healthier battery at 96%!

https://www.macrumors.com/2025/09/24/iphone-16-pro-max-charge-limit-test/

Now no matter which charging habit you choose, here’s what will damage the battery permanently. The first is letting the iPhone’s charge get very low below 20%, and worst, letting it die fully. If you ever get that low, be sure to charge your iPhone. It can also shut down as it gets closer to zero if you are running certain tasks, such as a long phone call. It is considered a deep discharge and causes additional stress on the battery to charge out of it. Even worse is leaving your iPhone’s battery dead for an extended period of time, which can permanently damage the battery and cause it to fall to sleep and never be able to turn on again. If you ever plan to go away from your iPhone for a while, be sure to power it off around fully charged. That’s the same reason why new iPhones in the box when opened are stored to around 50%, it’s best for long-term. In short, you should use Optimized Battery Charging to get the most usage on a daily basis.

In addition to applying to most other Apple products, these principles apply to all smartphones and other devices that use Lithium Ion batteries.

Some resources by Apple:

About Charge Limit and Optimized Battery Charging on iPhone - Apple Support