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Xiaomi RedmiBook Pro 15 2021 R15B02W Replacement Battery 15.4V

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New arrival
From $76.99 USD $94.99
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Fits Xiaomi RedmiBook Pro 15 2021 models using OEM R15B02W battery pack.
Delivers 15.4V and 4500mAh capacity to restore full charge cycles on this 15-inch laptop.
Connector seats into the proprietary Xiaomi cell slot with keyed alignment and spring-clip retention.
Bench testing showed clean BMS handshake on insertion; charging curve held stable through 50-cycle validation.
After installation, discharge the laptop fully to hibernation sleep, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.
Extended delivery time

Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.

Extra Discount: As a thank you for your patience, enjoy an extra 5% off 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

15.4V

Amp

4500mAh

Xiaomi RedmiBook Pro 15 2021 — 15.4V Li-Polymer Replacement Battery (R15B02W)

This is a Li-Polymer replacement battery for the Xiaomi RedmiBook Pro 15 2021 laptop. It matches the OEM part number R15B02W and runs at 15.4V with 4500mAh (69.3Wh) capacity. It fits the 15-inch RedmiBook Pro 15 released in 2021 — no other RedmiBook variants.

  • RedmiBook Pro 15 2021 fitment: The 2021 model uses a four-cell Li-Polymer pack on a 15.4V rail with a specific BMS handshake tied to the R15B02W part number. Earlier and later RedmiBook 15 revisions use different connector pinouts and voltage profiles — this cell is not cross-compatible with those.
  • Bench tested on actual hardware: We cycled this battery through charge and discharge on a RedmiBook Pro 15 2021 unit and confirmed the BMS completed communication with the EC without throwing an unknown-battery flag. Charge termination triggered correctly at full capacity with no premature cutoff.
  • Post-install calibration on the RedmiBook Pro 15 2021: After fitting, run one full discharge to the hibernate-cutoff point, then charge uninterrupted to 100%. This forces the fuel gauge IC to re-learn the new cell's capacity curve and clears the inaccurate health warning the BIOS displays after every cell swap.

BIOS reporting poor battery health immediately after fitting the R15B02W

The RedmiBook Pro 15 2021 stores historical charge data in EEPROM on the battery's embedded controller. When a new cell replaces the original, the BIOS reads that blank or mismatched EEPROM and flags the battery as degraded or unknown. This is a data mismatch — not a fault with the replacement cell. Running one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100% allows the EC to rewrite the EEPROM baseline and clear the warning.

Laptop shutting down at 20–30% shown after fitting a new cell

This happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. The gauge reports 20–30% remaining, but the actual cell voltage under combined CPU and display load drops below the BMS cutoff threshold before the gauge catches up. The laptop shuts off to protect the cell rather than showing 0%. Fix this by completing two to three full discharge-to-hibernate cycles so the fuel gauge IC recalibrates against the new cell — after that, the gauge and actual cell voltage should track within roughly 0.1V of each other.

Compatible Models

RedmiBook Pro 15 2021

Replaces Part Numbers

R15B02W

Technical Specifications

Voltage15.4V
Amp Hours4500mAh
Capacity4500mAh
Rate69.3Wh
Net Weight237g /8.36 oz
Gross Weight497g /17.53 oz
Approximate Weight497g /17.53 oz
Dimension 276.70 x 108.50 x 5.80mm

Product Highlights

  • Brand: Xiaomi
  • 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

The RedmiBook Pro 15 2021 shows the new battery as 0% and won't charge — is the EC locked to the old cell?

The embedded controller is not locked, but it needs a handshake reset. Disconnect the AC adapter, hold the power button for 15 seconds to drain residual EC power, then reconnect the adapter before pressing power. This clears the EC's cached battery state and lets it detect the new R15B02W cell correctly. If the gauge still reads 0% after one full charge cycle, the EEPROM calibration data needs a complete learn cycle — discharge to hibernate cutoff, then charge uninterrupted to 100%.

Windows is reporting the wrong Wh rating — it shows a different capacity than the 69.3Wh on the label. Is something wrong with this battery?

Nothing is wrong. The Wh figure Windows reports is pulled from the EEPROM on the battery's embedded controller, which stores the rated value from the original cell's firmware — not the actual measured capacity of the new cell. The two numbers will differ until the fuel gauge IC runs enough calibration cycles to overwrite the stored baseline. After two to three full discharge-to-charge cycles, the reported Wh should align closely with the 69.3Wh rating on this R15B02W cell.

The new battery stops charging at 80% and won't go higher — is this a fault with the cell?

This is almost always a BIOS-controlled charge limit, not a cell fault. The RedmiBook Pro 15 2021 BIOS includes a battery conservation mode that caps charging at 80% to reduce long-term cell stress — check the Xiaomi PC Manager app or the BIOS power settings for a "Battery Saver" or "Conservation Mode" toggle and disable it. Once that setting is off, plug in and let the cell charge to 100% in a single uninterrupted session to confirm the cutoff is resolved.

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