iPhone Battery Health Percentage: When It Is Time to Replace
The Maximum Capacity figure in your iPhone's battery settings shows how much charge the battery can hold now compared with when it was new. A reading of 85% means a full charge holds about 85% of what it originally did, so the phone runs out sooner. Here is what the numbers mean and when replacing the battery makes sense.
Where to find it
Open Settings > Battery > Battery Health & Charging (on some iOS versions, Battery Health). You will see:
- Maximum Capacity: the percentage of original capacity.
- Peak Performance Capability: whether the battery can still deliver enough power for full performance.
- On iPhone 15 and later, Settings also shows the battery's Cycle Count, manufacture date, and first use date, under Settings > General > About.
What counts as normal
Apple designs iPhone batteries to keep about 80% of original capacity at 500 complete charge cycles under normal conditions, and states that iPhone 15 models and later are designed to keep 80% at 1,000 cycles. A charge cycle is using 100% of the battery in total, which can be spread across several partial charges.
In practice:
| Maximum Capacity | What it usually means |
|---|---|
| 95–100% | Newer battery, little wear |
| 85–94% | Normal aging; noticeable but often still fine for a day |
| 80–84% | Approaching the replacement threshold; battery life is clearly shorter |
| Below 80% | Apple considers the battery significantly degraded |
Capacity tends to fall faster in the first months and then more slowly, so a phone that drops from 100% to 96% quickly is not necessarily defective.
The 80% line and the Service message
When the battery is significantly degraded, iOS shows a message such as Your battery's health is significantly degraded and the word Service. That is Apple's own recommendation that the battery be replaced. If your phone is under warranty or AppleCare+ and capacity is below 80%, the battery replacement may be covered; check with Apple.
Performance management
An aging battery cannot always deliver peak power, which can make the phone shut down unexpectedly under load. To prevent that, iOS may apply performance management after the first unexpected shutdown, which slightly limits peak speed. Battery Health will say so. You can turn it off, but if another unexpected shutdown happens, it turns back on. A new battery removes the need for it.
Why two phones the same age read differently
Two identical iPhones bought on the same day can show very different numbers a year later. Heavy daily use adds charge cycles faster, and a phone that is often hot, for example from gaming, navigation in a sunny car, or charging under a pillow, loses capacity faster than one kept cool. A phone that sits at 100% on a charger all day also ages a little faster. So a lower number than a friend's phone does not by itself mean something is wrong with yours.
When replacement makes sense
The percentage alone is not the only test. Consider replacing the battery if:
- The phone no longer lasts a normal day for you.
- It shuts down at 20% or 30%, or in cold weather.
- Battery Health shows Service or reports performance management.
- The phone feels slower than it used to during heavy tasks.
If your phone is at 83% and still gets you through the day, there is no urgency. If it is at 88% and dies by mid-afternoon, check what is draining it first, under Settings > Battery, because the problem may be an app rather than the battery.
Signs of a problem, not wear
Stop using the phone and get it checked if the screen is lifting, the case is bulging, or the phone gets hot while idle. A swollen battery can push the screen out and is a safety concern.
How to slow battery aging
- Avoid heat. High temperature is the biggest factor. Do not leave the phone in a hot car, and remove thick cases if it gets hot while charging.
- Use Optimized Battery Charging, on by default, which learns your routine and holds the charge at 80% until you need it.
- iPhone 15 and later also offer an 80% Limit charging option, which reduces wear further for people who keep their phone plugged in.
- You do not need to drain the battery to zero. Partial charges are fine.
About replacement batteries
After a battery replacement, iOS may show a notice in Battery Health if it cannot verify the battery as a genuine Apple part. The phone still works, but the health percentage may not display. Ask any repair shop what battery they use and what you will see in Settings afterward.
Help from Marion Phone Repair
Marion Phone Repair can check your battery's health and cycle count, tell you whether the drain is the battery or an app, and replace the battery if it is worn. We explain the parts we use and what your Battery Health screen will show afterward.
Battery Below 80%?
We replace iPhone batteries while you wait. Takes about 30 minutes. OEM-quality cells with warranty.
(740) 361-2306