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Redmi Note 9 Pro BN52 Compatible Battery 3.85V 4800mAh

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From $30.99 USD $38.99
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Fits Xiaomi Redmi Note 9 Pro, Note 9S — replaces OEM battery BN52.
3.85V nominal, 4800mAh capacity — supplies full day runtime on stock ROM without fast-charge mode.
Connector slides straight into the battery slot with no locking tab — orientation marked on both cell and housing.
Bench tested on M2003J6A1I; BMS accepted charge without fault codes through two full cycles at standard 5V input.
On first use after installation, disable fast charging for one complete discharge-charge cycle — this lets the fuel gauge IC recalibrate against the new cell discharge curve before high-current charging.
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

4800mAh

Redmi Note 9 Pro / Note 9S — 3.85V Li-Polymer Replacement Battery (BN52)

The BN52 is a 3.85V, 4800mAh Li-Polymer cell for the Redmi Note 9 Pro (M2003J6A1I) and Note 9S (M2003J6A1G). It replaces a degraded or damaged original battery when the phone no longer holds charge through a normal day. Capacity is 18.48Wh, matching the OEM specification.

  • Note 9 Pro and Note 9S platform fit: Both models run the same battery bay geometry, connector pinout, and BMS handshake protocol. The M2003J6A1I and M2003J6A1G share an identical voltage rail, so one cell fits both without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and load on the Note 9 Pro platform. The BMS accepted the charge IC handshake without fault flags, and protection circuits tripped correctly at both high-current and low-voltage thresholds.
  • Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated register.

Sudden shutdown at 20–30% on the Note 9 Pro after a cell swap

A new cell has a slightly different internal resistance profile than the worn cell the fuel gauge IC was calibrated against. Under modem radio or screen load, voltage sags faster than the coulomb counter predicts, and the protection circuit cuts power before the displayed percentage reaches zero. One full discharge-charge cycle at standard rate lets the IC rebuild its voltage-to-capacity map. After that cycle, shutdowns at 20–30% typically stop.

USB-PD or proprietary fast charge not activating on the first cycle after replacement

The charge IC on the Note 9 Pro negotiates fast charge only after it reads a valid cell temperature and impedance from the BMS. A new cell may present a higher initial impedance, causing the charge IC to stay in trickle or standard mode for the first cycle. This is normal and not a fault in the replacement cell. Let one full standard-rate charge complete — fast charge typically activates from the second cycle onward.

Compatible Models

Note 9 Pro M2003J6A1I Note 9S M2003J6A1G

Replaces Part Numbers

BN52

Technical Specifications

Voltage3.85V
Amp Hours4800mAh
Capacity4800mAh
Rate18.48Wh
Net Weight63.6g /2.24 oz
Gross Weight113.6g /4.01 oz
Approximate Weight113.6g /4.01 oz
Dimension 90.15 x 64.80 x 4.42mm

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 shuts off at around 25% after I put in the new battery — is something wrong with it?

Nothing is wrong with the cell. The fuel gauge IC was calibrated to the old battery's discharge curve, and the new cell's internal resistance causes voltage to sag under modem or screen load faster than the counter expects. Run one full discharge down to auto-off, then charge to 100% at standard rate without fast charging. After that cycle the IC recalibrates and the premature shutdowns stop.

The phone shows 100% for a long time then the percentage drops fast — why is the gauge behaving like this after replacement?

The coulomb counter inherited the old cell's charge curve and hasn't mapped the new one yet. It holds 100% until voltage drops past the stale reference point, then jumps down quickly. One complete discharge-charge cycle at standard rate forces the IC to relearn the new cell's actual voltage-to-capacity relationship. Erratic percentage readings normally settle after that first full cycle.

My Note 9 Pro won't turn on at all after the replacement battery sat in a drawer for a few months before I installed it — what do I do?

Li-Polymer cells self-discharge in storage, and if the cell dropped below roughly 2.5V the BMS entered lockout to prevent damage. Plug the phone into a wall charger — not a PC USB port — and leave it for 30 minutes without pressing the power button. The charge IC will trickle current into the cell until voltage rises above the BMS recovery threshold, after which the phone will boot normally.

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