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Redmi Note 12 4G BN5M Replacement Battery 3.87V 4900mAh

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Fits Xiaomi Redmi Note 12 4G, Redmi Note 12 4G NFC, and related variants using OEM part number BN5M.
Voltage is 3.87V nominal; capacity is 4900mAh (18.96Wh) — matches original cell discharge curve and modem load profile.
Connector is soldered JST directly to mainboard; polarity marked on cell frame; no locking tab present.
We bench-tested against a discharged OEM cell; BMS accepted charge without fault codes; fuel gauge IC read raw voltage on first cycle.
On first use after installation, disable fast charging for one complete discharge-charge cycle — this recalibrates the fuel gauge IC against the new cell discharge curve before high-current fast charging runs.
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

3.87V

Amp

4900mAh

Redmi Note 12 4G — 3.87V Li-Polymer Replacement Battery (BN5M)

This is a 3.87V, 4900mAh Li-Polymer replacement battery for the Xiaomi Redmi Note 12 4G smartphone. It carries OEM part number BN5M and fits models 23028RA60L, Note 12 4G NFC (23021RAA2Y), and related variants. Install it when the original cell no longer holds charge through a normal day or shuts down unexpectedly under load.

  • Note 12 4G variant coverage: The 23028RA60L and 23021RAA2Y share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell fits all listed variants without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the Note 12 4G platform. The BMS accepted the USB-PD and Xiaomi 33W fast charge handshake cleanly after the first complete cycle.
  • Fuel gauge recalibration on first use: 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 into an uncalibrated state.

Sudden shutdown at 20–30% on the Note 12 4G after a cell swap

A new Li-Polymer cell has a slightly different internal resistance profile than the worn cell the fuel gauge IC learned against. Under modem or display load, the new cell's voltage drops faster than the IC predicts, triggering a low-voltage cutoff well above the displayed percentage. The phone reads 25% but the cell voltage has already fallen below 3.5V at high draw. One full discharge-charge cycle with fast charging disabled corrects the coulomb counter and the shutdowns stop.

OS reports wrong battery percentage after replacement

The fuel gauge IC on the Note 12 4G stores a learned discharge curve from the original cell. A replacement cell with a different impedance curve makes those stored values inaccurate from the first boot. The percentage readout can jump, stall, or read 100% well before the cell is full. Run one full uninterrupted discharge down to auto-shutdown, then charge to 100% without interruption — this forces the IC to rewrite its reference curve against the new cell.

Compatible Models

Note 12 4G 23028RA60L Note 12 4G NFC 23021RAA2Y 23021RAA2G 23027RAD4I

Replaces Part Numbers

BN5M

Technical Specifications

Voltage3.87V
Amp Hours4900mAh
Capacity4900mAh
Rate18.96Wh
Net Weight66g /2.33 oz
Gross Weight116g /4.09 oz
Approximate Weight116g /4.09 oz
Dimension 89.20 x 64.00 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 12 4G won't turn on at all after the replacement battery sat in a drawer for a few weeks — is the cell dead?

Probably not dead, but the BMS has locked out below 2.5V per cell due to deep discharge in storage. Connect the phone to a low-current charger (a standard 5W USB adapter, not a fast charger) and leave it for 20–30 minutes without pressing any buttons. The BMS needs a trickle current to recover before it will allow a normal boot. If the charge LED doesn't appear within 45 minutes, the cell has dropped below recoverable threshold.

Fast charging stopped working on my Note 12 4G right after I fitted the new battery — it only charges slowly now.

On the first cycle after installation, the new BMS has not yet completed a handshake with the phone's charge IC for the 33W Xiaomi fast charge protocol. This is normal. Run one complete slow charge to 100%, then discharge fully, and fast charging will activate on the next session once the BMS handshake is confirmed. If it still fails after two full cycles, check that the USB-C port contacts are clean and the cable supports the 33W protocol.

The battery percentage on my Note 12 4G keeps jumping — it showed 60%, then jumped to 45% within seconds without any heavy use.

Erratic percentage jumps point to the fuel gauge IC recalibrating against the new cell's discharge curve. The IC's stored capacity model no longer matches the actual cell voltage behavior, so it corrects itself in sudden steps rather than smooth increments. Disable fast charging, run the phone down to automatic shutdown, then charge uninterrupted to 100% — after one full cycle the coulomb counter stabilises and the jumping stops.

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