What changed with iPhone 11 and later
On iPhone X and earlier a battery swap is a mechanical job: remove the old pack, fit the new one, done. From iPhone XS and especially iPhone 11 onward, iOS pairs the battery’s management chip with the logic board. Fit any battery the phone does not recognise and Settings shows a Service or Unknown Part notice, and Battery Health reports no maximum capacity. The phone charges and runs normally; only the health reporting is affected. The three battery types we sell exist because of this, so choose the type before you open the phone.
Choosing the battery type
| Type | What it is | Health shown? | Extra work |
|---|---|---|---|
| Original Chip | New cell paired with an original battery management chip | Yes, including cycles | None |
| Pre-Programmed (JCID) | Pack with a JCID-compatible chip, health data readable and editable | Yes, after programming | JCID programmer to write data |
| Cell Only (No Flex) | Bare cell, no flex | Depends on the flex you attach | Spot welding or soldering; reuse original flex or fit a tag-on flex |
| High Capacity | Cell with more mAh than stock (exact mAh on the listing) | Needs a matching flex | As above; check thickness fits the bay |
A battery marked Health-Tested has been checked for capacity, cycles and voltage before shipping, whatever its type. Every type is listed per model under iPhone Parts, for example iPhone 12 / 12 Pro, which share the same battery.
An honest word about what a programmer does: it does not make an aftermarket cell into an original one. It writes the serial, capacity and cycle count so the phone displays a reading. Whether iOS still shows a parts notice under About depends on the iOS version and the method, and that notice does not change performance.
Tag-on flex explained
A JCID battery tag-on flex clips onto the connector of a bare cell or a pack with an unrecognised chip and sits between the cell and the board. The programmer writes the health data to the tag-on flex, so the phone reads a normal battery with 0 cycles and the capacity you set. It is the usual route when a shop buys cells without flex in bulk and welds them. Tag-on flex cables are listed per model group on Programmers & Testers. Set the capacity to the real cell rating; writing a higher number only produces a battery that drops from 100 to 80 percent in an hour and a customer who comes back.
Step 1: open the phone and disconnect
- Discharge the phone below 25 percent before starting. A puncture on a full cell is far more violent than on a drained one.
- Remove the screen as described in the screen guide, or lift it enough to reach the connectors on models where the battery is accessible from the front. On iPhone 14 and 15 (non-Pro) the back glass is removable, and the battery is easier to reach from the back.
- Disconnect the battery connector first, then the display. Remove the taptic engine or loudspeaker if it blocks a pull tab.
Step 2: remove the old battery
- Locate the adhesive pull tabs (two on older models, four on 12 and later). Pull each slowly and at a low angle, parallel to the back of the phone. If a tab breaks, stop.
- With a broken tab, apply a few drops of isopropyl alcohol under the cell and wait, then lift with a plastic card. Never pry a battery with a metal tool and never bend the cell. iPhone 16 and later use adhesive that releases with low-voltage current; follow the model instructions.
- Do not apply heat directly to the cell. A heat mat under the phone at 60 °C for a minute is the limit.
A swollen battery gets separate treatment: open the phone without heat, do not press on it, and put the removed cell in a metal container with sand or a lithium battery bag. Do not stack swollen cells in a drawer.
Step 3: fit the new battery
- Clean the bay with isopropyl. Fit new adhesive strips, liner side up, then lay the battery flat and press for ten seconds.
- For a bare cell: weld or solder the original flex (or the tag-on flex) to the cell tabs before placing it, using a spot welder sized for phone cells such as the QianLi Macaron. Insulate the tabs with Kapton tape.
- Connect the battery last, after the display. Power on. If using a tag-on or JCID pre-programmed pack, run the programmer now and write capacity and serial.
- Check Settings > Battery > Battery Health. Then run a full charge and discharge cycle before handing over; the first reading can be off until the gauge calibrates.
Testing before you install
A battery tester or a board like the Mega-Idea iCharger 4.0 shows open-circuit voltage and charge current in seconds. A cell below 3.6 V from new stock or one that will not take current should not go into a customer’s phone. The RELIFE TB-06 Pro tester also reads cycles and capacity on original-chip packs. Both are in the programmers and testers category.
Safety summary
- Puncture, bending, or heat above 80 °C can ignite a lithium cell. Keep a bucket of sand or a Class D extinguisher within reach.
- Work on a non-conductive mat; a cell shorted by tweezers heats instantly.
- Spent cells are hazardous waste; collect them for proper recycling rather than general rubbish.
Batteries ship from China under lithium battery rules, which limits some courier options and quantities per parcel; see our shipping guide. Repair shops get wholesale pricing after approval.
FAQ
Why does the phone say Unknown Part after I fitted a new battery?
Because iOS could not match the battery chip to the logic board. Use an Original Chip pack, or program a JCID pack or tag-on flex. The notice does not affect charging or speed.
Can I reuse the original flex on a new cell?
Yes, if it was not damaged in removal. The original flex keeps the original chip, so health reporting works, but the cycle count carries over from the old battery unless you reset it with a programmer.
What capacity should I write with the programmer?
The rated capacity printed on the cell. Writing more only causes inaccurate percentage readings.
Is a High Capacity battery worth it?
For heavy users, yes, if the listing states the real mAh and the cell fits the bay without pressing on the screen. Expect a small gain, not double the run time.
How many cycles will the phone show after the swap?
Zero with an Original Chip pack or a freshly programmed tag-on flex; the old count with a reused original flex.