Two numbers, one chip
Every iPhone battery carries a small gas gauge chip on its flex. It counts the charge that goes in and out, estimates the remaining full capacity and stores the number of completed cycles. Settings, Battery, Battery Health reads those values and shows them as Maximum Capacity (a percentage) and, on newer models, Cycle Count. Neither number is measured by the phone itself; both come from the chip, which is why a replacement battery shows whatever its chip reports.
How a cycle is counted
One cycle is the use of 100 percent of the battery’s capacity, not one plug-in. Using 60 percent today and 40 percent tomorrow adds one cycle. Short top-ups from 70 to 90 do not add a full cycle each; they add fractions that sum up over time. The chip tracks the fractions internally and rounds the displayed figure.
What 80 percent means
Apple rates iPhone 14 and earlier batteries to keep 80 percent of original capacity at 500 full cycles, and iPhone 15 and later at 1,000 cycles. Below 80 percent the phone offers a service message and, on older models, may enable performance management that slows the processor to avoid shutdowns. For a repair shop, 80 percent and under is the honest replacement threshold; between 80 and 85 the customer decides based on how long the phone needs to last.
| Maximum Capacity | Typical age | What to tell the customer |
|---|---|---|
| 95 to 100 | Under a year | Normal; no action |
| 85 to 94 | One to two years | Normal wear; replace only if runtime is a problem |
| 80 to 84 | Two to three years | Replacement is reasonable |
| Under 80 | Three years or heavy use | Replace; the phone may throttle |
Where to find the cycle count
- iPhone 15 and newer, iOS 17.4 and later: Settings, Battery, Battery Health shows cycle count, manufacture date and first use date directly.
- iPhone 14 and earlier: there is no cycle count in Battery Health. Read it with a programmer such as JCID V1SE or QianLi iCopy connected to the battery flex, with a Mac tool such as coconutBattery, or from the analytics log under Settings, Privacy and Security, Analytics Data, which is tedious but free.
- Repair shop practice: read the cycle count with a programmer before and after the job and note both on the work order. It settles disputes later.
What replacement batteries show
This is where grades matter. The phone reads the chip, and the chip reports what it was built or programmed to report.
- Original pull battery: shows its real history, for example 91 percent and 240 cycles. On iPhone 12 and newer the Parts and Service History line says Used after Repair Assistant, or Unknown Part if calibration was skipped.
- Original Chip (new cell on an original flex): the chip is reset or carries the cell’s real values, so health shows close to 100 percent and a low cycle count. The log still says Unknown Part on tracked models because the pairing does not match.
- Aftermarket battery with its own chip: before iOS 18.1 many of these showed “Unable to verify” and no percentage at all. Since iOS 18.1 most report health and cycles normally; the log says Unknown Part.
- Pre-Programmed (JCID): the chip is compatible with JCID tools, so the shop can read it, set the cycle count to zero and correct the capacity figure before installation.
- Cell only with tag-on flex: the tag-on flex carries the chip and is written with the phone’s original battery data using the JCID programmer, so the phone sees a matching serial and shows health without the pop-up. Our guide on using a JCID programmer covers the procedure.
Whatever the grade, do not promise a customer that health will show 100 percent after the job unless you have read the chip yourself. Listings in our iPhone parts catalogue state the grade and whether the battery is Health-Tested; see also how to replace an iPhone battery.
Reading the numbers critically
A new battery that shows 100 percent and 0 cycles may be a fresh cell, or a used cell with a reset chip. The only reliable test is capacity: charge to full, discharge under a known load with a tester, and compare the measured mAh to the rating. Testers such as the Mega-Idea battery detection board and the QianLi Apollo show voltage, real-time current and reported capacity, which is enough to catch cells that are far below rating. Cross-check against the figures in our listings: an iPhone 13 cell is rated 3,227 mAh and an iPhone 15 Pro cell 3,274 mAh, so a tester reading of 2,600 mAh on a “new” cell means it is not new.
Why health drops faster than expected
- Heat. Charging in a hot car or gaming while charging ages a cell faster than cycles do.
- Deep discharges to zero. A phone that shuts down daily loses capacity sooner.
- Fast charging at high state of charge. Keeping Optimized Battery Charging on helps.
- A miscalibrated chip. If health jumps around by several points, recalibrate by running the phone from full to empty and charging to full once; the figure settles.
Safety note
A low health figure is a wear indicator, not a safety warning. A battery that is swollen, hot while idle or smells sweet is a safety problem at any percentage; power the phone off and replace the battery. Never puncture a cell when removing it, and keep a sand bucket or a fireproof pouch on the bench.
FAQ
Can I see the cycle count on an iPhone 13?
Not in Settings. Use a programmer on the battery flex, a Mac app, or the analytics log. iPhone 15 and newer show it in Battery Health.
Why does my new battery show 97 percent?
Capacity estimates start slightly below 100 on many chips and settle after a few cycles. If it stays under 95 after a week, the cell is below rating.
Does resetting the cycle count make the battery new?
No. It changes the number the phone displays, not the chemistry inside the cell. Only a capacity test tells you the real state.
Why did health disappear after I fitted the battery?
On iOS versions before 18.1 an unrecognised chip hid the percentage. Update iOS, or use a battery with an original or JCID-compatible chip.
What is a normal cycle count per year?
Most users add 300 to 400 cycles a year. A phone with 1,000 cycles on an iPhone 14 or earlier is well past the rated life.