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Apple iPhone 12 A2479 Replacement Battery 3.83V 3350mAh

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From $34.99 USD $43.99
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Fits Apple iPhone 12, iPhone 12 Pro, iPhone 12 Max; replaces OEM part A2479.
This 3.83V, 3350mAh lithium-polymer cell restores full charge capacity to the iPhone 12 platform.
Connector seats flush into the battery slot without physical modification or adhesive rework required.
We bench-tested this cell in an iPhone 12 chassis; the BMS accepted the pack on first insertion and delivered stable voltage under standby and modem load.
On first use after installation, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC recalibrate against the new cell's discharge curve.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.83V

Amp

3350mAh

Apple iPhone 12 / iPhone 12 Pro — 3.83V Li-Polymer Replacement Battery (A2479)

This 3.83V, 3350mAh lithium-polymer battery replaces the original A2479 / A2431 cell in the iPhone 12 and iPhone 12 Pro. It fits the A2408 variant as well. The physical dimensions match the original bay at 84.20 × 44.54 × 4.40mm, so no trimming or bracket modification is needed.

  • iPhone 12 and 12 Pro shared platform: Both models run the same A14 Bionic voltage rail and use an identical battery connector and BMS handshake. One cell covers both devices without wiring adaptation.
  • Bench tested on actual hardware: We cycled this cell through the iPhone 12 charge IC under load. The BMS accepted the charge profile without dropping into fault state, and the fuel gauge IC completed its first-cycle coulomb count without error flags.
  • Fuel gauge recalibration after install: On first use after installation, disable fast charging for one complete discharge-to-charge cycle. This lets the fuel gauge IC build a fresh discharge curve against the new cell before high-current USB-PD pushes amperage into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on a replacement iPhone 12 cell

This happens when the fuel gauge IC is still running the discharge curve from the old degraded cell. The new cell hits a voltage cliff under 5G modem or display load that the old curve did not predict. iOS interprets the drop as a low-voltage cutoff and shuts down before the percentage reaches zero. One full discharge cycle — drain to auto-off, then charge uninterrupted to 100% — forces the fuel gauge IC to remap the curve against the new cell's actual capacity.

iOS percentage jumping erratically after battery replacement

Erratic percentage jumps are a coulomb counter recalibration issue, not a faulty cell. The fuel gauge IC uses stored data from the previous cell's impedance and discharge profile, which no longer matches the replacement. Values appear to skip or bounce until the IC gathers enough current-in and current-out data to reset its model. Run two to three full discharge-charge cycles without interruption and the readings stabilise — look for the percentage to increment smoothly and hold steady at rest above 3.7V open-circuit.

Compatible Models

iPhone 12 iPhone 12 Pro iPhone 12 Max A2408

Replaces Part Numbers

A2479 A2431

Technical Specifications

Voltage3.83V
Amp Hours3350mAh
Capacity3350mAh
Rate12.83Wh
Net Weight43g /1.52 oz
Gross Weight93g /3.28 oz
Approximate Weight93g /3.28 oz
Dimension 84.20 x 44.54 x 4.40mm

Product Highlights

  • Brand: Apple
  • Manufacturer: CS
  • Series: X-Longer
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My iPhone 12 won't power on at all after the battery sat in a drawer for a few months — is the cell dead?

Likely not dead, but the BMS has locked out below 2.5V per cell after deep self-discharge in storage. Plug into a wall adapter — not a computer USB port — and leave it for 20–30 minutes without pressing any buttons. The charge IC needs to trickle current past the lockout threshold before the BMS will allow a normal charge cycle to begin. If the Apple logo appears and then disappears repeatedly, let it sit on charge for a full hour before attempting to boot.

Fast charging stopped working the first time I plugged in after swapping the battery — USB-PD shows as regular charging only.

This is a first-cycle BMS behaviour. The new cell's BMS does not immediately negotiate the USB-PD handshake until it completes one standard charge cycle at base current. Complete one full charge to 100% on a standard 5W or 12W adapter, then reconnect your USB-PD charger. The fast charge protocol should negotiate correctly on the second cycle. If it still shows standard charging, check that the Lightning connector is clean — debris interrupts the USB-PD negotiation signal before it reaches the charge IC.

The phone feels warm near the back during the first few charges after replacing the battery — is the charge IC overheating?

Warmth on the first few cycles is normal with a new high-impedance cell. A fresh lithium-polymer cell has higher internal resistance until it is conditioned, which causes the charge IC to dissipate more heat than it will once the cell breaks in. Keep the phone out of its case for the first two or three charge cycles so heat can escape the aluminium frame. If the back becomes hot enough to be uncomfortable to hold — above roughly 45°C — remove it from charge and let it cool before resuming.

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