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. Feedback is welcome.

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 but in reality, it may be better by a few battery health percent over a few years, which is very only marginal. You also have to charge your iPhone more often which will degrade the battery faster. In addition to the caveat, your iPhone will still charge to 100% “occasionally”. There is no set definition of the word “occasionally”, it can be weekly, monthly, somewhere in between or more. It will vary by person, this is because your iPhone learns from each and every person’s unique usage, charge schedules, battery state and determines when to do this. In addition, many senior community members believe that Charge Limits are merely to give some users a way of micromanaging their battery. If it really were important and the best charging habit, Apple surely would have released it to most supported iPhone models, but they chose only the newest ones.

Compared to Optimized Battery Charging which has been around for the longest of time for about most 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. Most senior members will suggest Optimized Battery Charging, that is usually a better charging habit for most users.

But in reality for battery longevity, comparing all the charge habits none really make a big difference with each other. What will damage the battery permanently and cause it to degrade faster 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 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