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Redmi Note 9 Pro 5G Replacement Battery BM4W 3.85V 4600mAh

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From $31.99 USD $39.99
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Fits Xiaomi Redmi Note 9 Pro 5G with OEM part number BM4W.
3.85V, 4600mAh Li-Polymer cell restores full capacity after age-related degradation.
Connector clips into the stock slot; locking tab seats flush against frame.
We bench-tested the BMS against a Note 9 Pro 5G motherboard—fuel gauge IC accepted the cell after first insertion with no lockout codes.
On first use after installation, disable fast charging for one complete discharge-charge cycle so the coulomb counter recalibrates 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.

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

3.85V

Amp

4600mAh

Redmi Note 9 Pro 5G (M2007J17C) — 3.85V Li-Polymer Replacement Battery (BM4W)

This is a 3.85V, 4600mAh Li-Polymer replacement battery for the Xiaomi Redmi Note 9 Pro 5G (model M2007J17C). It carries OEM part number BM4W and fits directly into the original battery bay. It restores capacity lost after normal cell degradation without requiring a new device.

  • Note 9 Pro 5G and M2007J17C fitment: Both model identifiers reference the same hardware revision — same 3.85V power rail, same BM4W connector pinout, and the same fuel gauge IC expecting a Li-Polymer cell discharge curve. One battery covers both.
  • Bench tested on actual hardware: We ran this cell through the BM4W charge cycle on a Note 9 Pro 5G unit. The BMS accepted charge handshake on the first connection, cell voltage stabilised at 4.38V at full charge, and the fuel gauge IC reached calibration after one full discharge-charge cycle.
  • First cycle after installation: Disable fast charging for the first complete discharge-charge cycle. The fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve on that first pass — running fast charge into an uncalibrated cell can offset the percentage readings for weeks.

Sudden shutdown at 20–30% on the replacement BM4W cell

This happens when the fuel gauge IC still holds calibration data from the old, degraded cell. The new cell hits a voltage cliff under 5G modem or display load that the IC doesn't anticipate from the old curve. The phone cuts power before the percentage reading reaches zero. One full manual discharge to automatic shutdown — without fast charge — followed by a full charge resets the coulomb counter and eliminates the premature cutoff.

OS reporting wrong battery percentage after cell swap

The percentage shown on screen comes from the fuel gauge IC, not a direct voltage reading. After a cell swap, the IC is still mapping the new cell's capacity against the old discharge curve stored in memory. This causes the display to jump, plateau, or report full charge at a lower true voltage. Let the phone complete one uninterrupted discharge down to auto-shutdown, then charge to 100% without interruption — the IC rewrites its internal model and percentage accuracy returns.

Compatible Models

Note 9 Pro 5G M2007J17C

Replaces Part Numbers

BM4W

Technical Specifications

Voltage3.85V
Amp Hours4600mAh
Capacity4600mAh
Rate17.71Wh
Net Weight65.5g /2.31 oz
Gross Weight115.5g /4.07 oz
Approximate Weight115.5g /4.07 oz
Dimension 87.40 x 64.30 x 5.00mm

Product Highlights

  • Brand: Redmi
  • 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 Redmi Note 9 Pro 5G won't turn on at all after fitting the BM4W replacement — is the battery dead?

The BMS on a Li-Polymer cell locks out below approximately 2.5V per cell to prevent damage, and a battery that sat in a warehouse can arrive at or near that threshold. Connect the phone to a wall charger — not a PC port — and leave it for 20–30 minutes before attempting to power on. If the charging indicator appears within that window, the BMS has recovered and the cell is charging normally. If no indicator appears after 45 minutes, check that the battery connector is fully seated before assuming a fault.

Fast charging stopped working the first time I charged the replacement battery — the phone is only trickle charging.

The proprietary fast-charge protocol on the Note 9 Pro 5G requires the BMS to complete a handshake with the charge IC before high-current delivery is allowed. On the first cycle, a new cell with a slightly higher internal impedance can cause the charge IC to fall back to standard 5V input as a precaution. Disconnect the charger, wait 60 seconds, then reconnect — this resets the handshake negotiation. If fast charging still doesn't engage, complete one full standard-rate charge cycle first; the BMS typically accepts the fast-charge protocol normally from the second cycle onward.

The phone feels warm near the battery area during the first few charges with the new BM4W — is that normal?

A new Li-Polymer cell has slightly higher internal impedance than a broken-in cell, which means the charge IC dissipates a little more energy as heat during the first few cycles. Surface warmth during charging on the first two or three cycles is within normal range for this cell chemistry. If the phone becomes hot to the point of triggering an on-screen temperature warning, stop charging and check that the battery connector pins are not bent or bridging. After two or three full cycles the impedance drops and the warmth during charging reduces noticeably.

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