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Poco M4 Pro 5G BN5C Replacement Battery 3.87V 4900mAh

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From $33.99 USD $41.99
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Fits Poco M4 Pro 5G (OEM part BN5C) smartphone battery slot.
3.87V, 4900mAh Li-Polymer cell restores full charge capacity to the display and modem.
Connector aligns vertical into the spring-clip slot; no locking tab — slides straight down.
We bench-tested the BMS on a live M4 Pro 5G board; voltage held steady under 2A discharge load.
On first use after installation, disable fast charging for one complete discharge-charge cycle — the fuel gauge IC needs to recalibrate against this cell's discharge curve before high-current charging resumes.
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

3.87V

Amp

4900mAh

Poco M4 Pro 5G — 3.87V Li-Polymer Replacement Battery (BN5C)

This is a 3.87V, 4900mAh Li-Polymer replacement battery for the Poco M4 Pro 5G smartphone (model numbers 21091116AG and MZB0BGVIN). It slots into the original battery position and connects to the same BMS handshake points the phone expects. Rated at 18.96Wh, it restores full power to the display, processor, modem, and connectivity stack.

  • M4 Pro 5G platform fit: The 21091116AG and MZB0BGVIN variants share the same battery bay dimensions and the same fuel gauge IC wiring. Both accept the BN5C connector pinout without modification.
  • Bench tested on actual hardware: We ran this cell on the M4 Pro 5G and confirmed the BMS negotiated charge acceptance correctly, with the protection circuit triggering at the expected cutoff voltage on discharge.
  • First-cycle fast charge lockout: On first use after installation, disable fast charging and run one full discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the replacement cell

A new cell has a slightly different voltage-discharge curve than the degraded cell the fuel gauge IC learned. When the phone hits a voltage cliff — the point where cell voltage drops sharply under modem or screen load — the IC hasn't mapped that cliff yet and shuts down early. One complete slow charge-discharge cycle forces the coulomb counter to re-learn the new curve. After that cycle, shutdowns at high reported percentages typically stop.

OS reporting wrong battery percentage after cell swap

The fuel gauge IC stores a learned capacity model tied to the old cell's impedance and voltage profile. Drop in a new cell and the IC is reading against the wrong model, so the percentage display jumps erratically or reads high until sudden shutdown. A full discharge to automatic power-off, followed by a full charge to 100%, forces the IC to write a new baseline. After that first calibration cycle, percentage accuracy should stabilise within a few percent.

Compatible Models

M4 Pro 5G 21091116AG MZB0BGVIN

Replaces Part Numbers

BN5C

Technical Specifications

Voltage3.87V
Amp Hours4900mAh
Capacity4900mAh
Rate18.96Wh
Net Weight66.2g /2.34 oz
Gross Weight116.2g /4.10 oz
Approximate Weight116.2g /4.10 oz
Dimension 88.60 x 64.15 x 5.00mm

Product Highlights

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

Frequently Asked Questions

My Poco M4 Pro 5G won't turn on at all after the replacement battery sat in a drawer for a few months — is the battery dead?

Most likely the cell discharged below 2.5V during storage, which triggers BMS lockout — the protection circuit disconnects the cell to prevent damage, and the phone sees no power at all. Plug in the original charger and leave it connected for 15–20 minutes without pressing the power button; the charge IC needs to push a small trickle current through the BMS to bring the cell voltage back above the lockout threshold. Once the charging indicator appears, charge fully before booting. If no indicator appears after 30 minutes, the cell may have discharged too deeply to recover and will need replacement.

Fast charging stopped working after I put the new BN5C battery in — the phone just charges slowly now.

On the first charge cycle after a cell swap, the USB-PD or proprietary fast charge protocol sometimes fails to negotiate because the BMS on the new cell hasn't completed its initial handshake with the phone's charge IC. Run one full slow charge to 100%, then disconnect and allow the phone to boot and settle for a few minutes. Reconnect the original charger — fast charge negotiation typically succeeds from the second cycle onward once the BMS has completed its initialisation sequence.

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

A new Li-Polymer cell starts with higher internal impedance than a broken-in cell, so the charge IC pushes more voltage across a higher-resistance cell, which generates more heat in the first few cycles. Warmth during charging is expected and typically reduces after three to five full charge cycles as the cell's impedance settles. If the phone becomes hot to the touch rather than just warm, or if charging stops before 100%, check that the charging port is clean and that the connector is fully seated. After the break-in cycles, charge temperature should return to the same range you experienced with the original battery.

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