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Apple iPhone 15 Replacement Battery A3018 3.85V 3500mAh

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Fits Apple iPhone 15 and replaces OEM battery part number A3018.
Voltage 3.85V and capacity 3500mAh deliver the same charge window as factory cells in iPhone 15.
Connector orientation matches Apple's internal flex design; no adhesive tabs or mechanical locks to manage.
We ran full discharge cycles on iPhone 15 — fuel gauge IC accepted the new cell without voltage errors on cycle two.
On first use after installation, disable fast charging for one complete discharge-charge cycle to let the coulomb counter recalibrate against this 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.

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⚠️ 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

3.85V

Amp

3500mAh

Apple iPhone 15 — 3.85V Li-Polymer Replacement Battery (A3018)

This is a 3.85V, 3500mAh Li-Polymer replacement battery for the Apple iPhone 15. It fits the iPhone 15 only — not the Plus, Pro, or Pro Max. Voltage and capacity match Apple's OEM specification for this model.

  • iPhone 15 fitment: The iPhone 15 uses a specific connector orientation and BMS handshake protocol tied to the A3018 cell. Other iPhone 15 variants run different voltage rails and fuel gauge calibration — this cell is matched to the base iPhone 15 board only.
  • Bench tested on actual hardware: We ran this cell through a full charge cycle on an iPhone 15 unit. The BMS accepted the charge handshake without error, and the charge IC stepped through trickle, constant-current, and constant-voltage phases normally.
  • Fuel gauge recalibration after install: After fitting this cell, disable fast charging and run one complete discharge-charge cycle at standard 5W. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the replacement cell

A new cell has a discharge curve the iPhone's fuel gauge IC has never seen. Under high-current load — 5G modem switching, ProRAW processing, or screen at full brightness — the cell voltage can dip below the BMS cutoff threshold even when the reported percentage looks safe. The phone reads 25% but the instantaneous voltage under load drops below 3.4V, triggering a hard shutdown. Run one full discharge to 1–2% followed by a complete charge to 100% to let the coulomb counter recalibrate against actual cell capacity.

USB-PD fast charge not accepted on first cycle after replacement

On the first charge cycle, the iPhone 15's charge IC may not negotiate full USB-PD fast charge with a replacement cell — it defaults to a lower current rate while the BMS and fuel gauge IC finish initial calibration. This is not a fault with the adapter or the cell. Use a standard 5W charge for the first full cycle, then reconnect a USB-PD adapter. Fast charge should negotiate normally from the second cycle onward at the expected 18W input rate.

Compatible Models

iPhone 15

Replaces Part Numbers

A3018

Technical Specifications

Voltage3.85V
Amp Hours3500mAh
Capacity3500mAh
Rate13.48Wh
Net Weight45g /1.59 oz
Gross Weight95g /3.35 oz
Approximate Weight95g /3.35 oz
Dimension 87.40 x 44.00 x 4.80mm

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 15 keeps shutting off at around 25% after fitting the new battery — is the cell defective?

The cell is almost certainly fine. The fuel gauge IC on the iPhone 15 is still calibrated to the old cell's discharge curve, so voltage readings under modem or screen load are inaccurate. When instantaneous cell voltage drops below 3.4V under high current draw, the BMS triggers a hard cutoff even though the displayed percentage looks safe. Run one complete discharge to near 1% and a full uninterrupted charge to 100% — the coulomb counter will remap to the new cell and the shutdowns should stop.

The battery percentage is jumping around erratically after I swapped the cell — it went from 60% to 43% in seconds with no heavy use.

This is the fuel gauge IC recalibrating against a cell it has no historical data for. The coulomb counter uses charge and discharge history to estimate state-of-charge, and a new cell resets that history entirely. Percentage jumps and sudden dips are normal for the first one to three cycles. Complete two full discharge-charge cycles without interruption and the readings will stabilise as the IC builds an accurate model of the new cell's capacity curve.

The phone feels noticeably warm near the battery area during charging — is that normal with a new cell?

A new Li-Polymer cell typically has slightly higher internal impedance than a broken-in cell, which means the charge IC dissipates more heat during the constant-current phase on the first few cycles. This usually resolves by the third or fourth full charge as the cell's impedance settles. If the phone feels hot enough to be uncomfortable to hold, stop the charge, let it cool to room temperature, and resume. Impedance-related warmth should drop off noticeably after two to three full cycles.

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