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Apple iPhone 15 Plus A3039 Replacement Battery 3.85V 4650mAh

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From $43.99 USD $54.99
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Fits Apple iPhone 15 Plus, replaces OEM part number A3039.
This 3.85V, 4650mAh Li-Polymer cell restores the iPhone 15 Plus to original power draw capacity during typical daily use.
Connector is a proprietary five-pin flex cable with one-way orientation — tab locks into the upper logic board slot, no keying needed.
We bench-tested the cell on an iPhone 15 Plus motherboard; the fuel gauge IC accepted the new BMS handshake without fault codes after a clean connector reseat.
On first charge after installation, disable fast charging for one complete discharge-charge cycle — this lets the coulomb counter recalibrate against the new cell 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

4650mAh

Apple iPhone 15 Plus — 3.85V Li-Polymer Replacement Battery (A3039)

This is a 3.85V, 4650mAh (17.9Wh) Li-Polymer battery for the Apple iPhone 15 Plus. It replaces part number A3039 — the original cell fitted to this model at manufacture. Fit this when the original cell has lost capacity through normal charge cycling and can no longer sustain the phone under load.

  • iPhone 15 Plus fit: The A3039 cell uses a specific flex connector and BMS handshake tied to the iPhone 15 Plus power management IC. The physical dimensions — 98.80 × 50.00 × 4.80mm — match the battery bay exactly. No adapter or modification is needed.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an iPhone 15 Plus unit. The BMS accepted the full charge cycle without cutoff errors, and the power management IC reported capacity correctly after the fuel gauge completed its first calibration pass.
  • Fuel gauge recalibration on first install: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes additional load into an uncalibrated cell.

Why the iPhone 15 Plus reports wrong battery percentage after a cell swap

The fuel gauge IC on the iPhone 15 Plus uses a coulomb counter calibrated to the old cell's discharge curve. After fitting a new cell, the stored curve no longer matches actual cell voltage behaviour. The percentage reading drifts — often showing 100% then dropping fast, or stalling at mid-range. One full discharge down to automatic shutdown followed by a complete charge to 100% forces the coulomb counter to remap against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC hasn't yet aligned its voltage threshold map to the new cell. The new cell may hit a voltage cliff — dropping below the modem or display's minimum rail voltage — before the reported percentage reaches zero. The phone shuts down as a protective measure, not because the cell is faulty. Run one full discharge-to-shutdown and full recharge cycle; the fuel gauge recalibrates its low-voltage cutoff point against the actual cell, and the shutdowns stop.

Compatible Models

iPhone 15 Plus

Replaces Part Numbers

A3039

Technical Specifications

Voltage3.85V
Amp Hours4650mAh
Capacity4650mAh
Rate17.9Wh
Net Weight58g /2.05 oz
Gross Weight108g /3.81 oz
Approximate Weight108g /3.81 oz
Dimension 98.80 x 50.00 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

USB-PD fast charging isn't working on my iPhone 15 Plus after fitting the new battery — it only shows slow charging. Why?

On the first cycle after a cell swap, the charge IC sometimes defaults to a lower current profile until the BMS completes its initial handshake with the power management IC. This is a one-cycle behaviour, not a fault. Let the phone complete one full slow charge to 100%, then reconnect your USB-PD charger — fast charging resumes once the BMS has confirmed cell parameters to the charge IC.

My iPhone 15 Plus feels warm near the battery during the first few charges after the swap. Is something wrong?

A new high-impedance cell generates slightly more heat during early charge cycles than a broken-in cell. The internal resistance drops as the cell conditions through the first two or three full cycles. If the warmth is concentrated at the battery and not at the charging port, this is normal. If the phone becomes hot to the touch or throws a temperature warning on-screen, stop charging and check the flex connector is fully seated — a partial connection raises contact resistance and heat.

The phone won't power on at all after the new battery sat in storage for a few weeks before I installed it. What do I do?

A Li-Polymer cell stored below roughly 2.5V per cell triggers BMS lockout — the protection circuit disconnects the cell to prevent damage, and the phone won't respond to the power button or show a charging screen. Connect the phone to a low-current charger (a standard 5W USB-A brick works well here) and leave it for 20–30 minutes without pressing anything. Once the cell voltage climbs above the BMS recovery threshold, the phone will show the low-battery charging screen and boot normally.

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