Short answer: Open Settings → Battery → Battery Health & Charging and read the Maximum Capacity figure. Apple treats 80% as the point where a battery needs replacing. Anything in the 80s is a battery already on its way out — which is why “above 80%” is a warning in a listing, not a selling point. A properly renewed iPhone should read 100%.
How to check iPhone battery health in 10 seconds
- Open Settings
- Tap Battery
- Tap Battery Health & Charging
- Read Maximum Capacity
That percentage is the battery's current capacity measured against what it held when it was new. A reading of 87% means the battery now holds 87% of the charge it originally did — you are losing roughly an eighth of your day, every day.
On iPhone 15 and later you can also see the exact cycle count under Settings → General → About. One cycle equals one full charge worth of use, not one plug-in.
What battery health number is actually acceptable?
| Reading | What it means in practice |
|---|---|
| 100% | New, or a genuinely replaced battery. Full day of use. |
| 95–99% | Lightly used. You will not notice a difference yet. |
| 90–94% | Normal ageing. Slightly shorter evenings. |
| 85–89% | Noticeably shorter days. Degradation accelerates from here. |
| 80–84% | Near end of service life. Expect a charger by evening. |
| Below 80% | Apple flags this for replacement. Performance throttling may kick in. |
Apple designs iPhone batteries to retain around 80% of original capacity after 500 complete charge cycles — and on iPhone 15 and later, after 1,000 cycles. Once a battery crosses below that line, iOS may begin managing peak performance to prevent unexpected shutdowns, which is where the “my old iPhone feels slow” complaint actually originates. It is usually not the processor. It is the battery.
Why “above 80% battery health” is a red flag, not a promise
Scroll any second-hand listing in India and you will see the phrase everywhere. It sounds like a guarantee. It is the opposite.
“Above 80%” is the widest possible claim a seller can make while still technically telling the truth. It covers a battery at 99% and a battery at 81% equally. And a battery at 81% is one that Apple itself considers close to end of life — you are buying a phone that needs a battery replacement almost immediately, at your cost.
The tell is the vagueness. A seller who has actually replaced the battery states a number. A seller who has not gives you a range.
This is the single most common way buyers get caught out in India's second-hand market, and it is why we do not participate in it. Every Premium Renewed iPhone from Control Z ships at 100% battery health, because the battery is replaced during renewal rather than carried over from the previous owner.
Things that distort the reading
A few situations produce numbers that do not mean what they appear to.
A recently reset battery. Some sellers use tools that reset the reported capacity to 100% without changing the physical battery. The giveaway is cycle count — a genuinely new battery has a low cycle count. A reset one shows 100% capacity alongside hundreds of cycles.
Third-party batteries. If a non-genuine battery has been fitted, iOS often shows an “Unknown Part” notice or hides the health reading entirely. A missing Battery Health section on a modern iPhone is not a glitch. It means someone has been inside the phone.
A phone that has just been charged to full. Capacity readings recalibrate over a few charge cycles. A number taken minutes after unboxing can drift slightly in either direction over the first week.
How to make a battery last longer
Heat is the real enemy, more than charging habits. Avoid leaving the phone in a car, on a dashboard, or charging under a pillow. Keep Optimised Battery Charging switched on so the phone learns your routine and delays the final stretch to 100% until you need it. And stop worrying about charging overnight — modern iPhones manage that themselves.
Realistically, expect to lose a few percentage points a year with normal use. Starting from 100% instead of 85% is what buys you the extra two years.
Before you buy any used or renewed iPhone
Check the battery health yourself before money changes hands, and check the cycle count alongside it. If the seller will not let you open Settings, walk away.
Battery is one of several things worth verifying. Our full 9-step checklist for verifying a refurbished phone covers the rest, and the IMEI verification guide covers how to confirm the device is not stolen or blacklisted before you pay.
If you would rather skip the inspection entirely, this guide explains whether a renewed iPhone is worth it and what a real renewal process looks like.
Frequently asked questions
Where is battery health on an iPhone?
Settings → Battery → Battery Health & Charging. The Maximum Capacity percentage is the figure that matters. This is available on iPhone 8 and later.
Is 85% battery health good for a used iPhone?
No. At 85% the battery is already past the halfway point of its useful life and degradation accelerates from there. You would likely need a replacement within a year.
What battery health does a Control Z renewed iPhone have?
100%. The battery is replaced as part of the renewal process on every device, rather than carried over from the previous owner.
Why can't I see Battery Health on my iPhone?
Usually because a non-genuine battery has been fitted. iOS hides or flags the reading when it cannot verify the part. Treat a missing Battery Health section as a sign the phone has been opened.
What is a good cycle count for an iPhone?
Under 200 cycles is low. Apple rates batteries to hold about 80% capacity at 500 cycles, and at 1,000 cycles on iPhone 15 and later. Always read cycle count together with capacity — a 100% reading with a high cycle count suggests the figure has been reset rather than the battery replaced.
Does battery health affect iPhone performance?
Yes. Once capacity drops below roughly 80%, iOS may limit peak performance to prevent sudden shutdowns. Most “my iPhone got slow” complaints are battery ageing, not the processor.
