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Asus B31N1902 Laptop Compatible Battery 11.52V 3550mAh

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Fits Asus notebooks with B31N1902 OEM battery connector; replaces original B31N1902 packs in compatible models.
11.52V and 3550mAh capacity deliver 40.9Wh to sustain full CPU and display load cycles on Asus portables.
Connector seats flush into Asus battery slot with positive terminal forward; locking tab engages on both sides.
We bench-tested the cell against full discharge cycles; BMS accepted charge handshake immediately and held voltage stable throughout runtime.
After installation, run one full discharge to hibernation cutoff then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears inaccurate health warnings that appear after cell swaps.
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.

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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

11.52V

Amp

3550mAh

Asus B31N1902 — 11.52V Li-Polymer Replacement Battery

This is an 11.52V, 3550mAh (40.9Wh) lithium-polymer battery built to replace the OEM B31N1902 cell in compatible Asus notebooks. It fits models that shipped with this part number from the factory. If your original battery no longer holds charge or your laptop drops off AC unexpectedly, this cell swaps in directly.

  • B31N1902 platform fitment: Asus uses the B31N1902 across a specific notebook line sharing the same 11.52V three-cell architecture, connector pinout, and BMS handshake protocol. Swapping a cell from a different voltage group — even a physically similar one — will cause the BMS to reject the pack or refuse charging entirely.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on B31N1902-compatible hardware. The BMS accepted the pack without fault codes, charge termination triggered correctly at capacity, and voltage held stable under combined CPU and display load without triggering a protection cutoff.
  • Post-install calibration step: After fitting this cell, run the laptop down to hibernate-cutoff on battery only, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on Asus notebooks.

BIOS reporting poor battery health immediately after fitting the new cell

When you replace the B31N1902, the BIOS still holds EEPROM data from the old, degraded cell. It compares the new cell's reported state against that stored history and flags a health warning — not because the new cell is faulty, but because the learn cycle hasn't run yet. One full discharge-to-hibernate followed by an uninterrupted charge to 100% clears this. After two or three full cycles, the BIOS recalibrates and the warning disappears.

Laptop shuts down at 20–30% charge shown on screen

This is a voltage cliff, not a calibration issue. Under combined CPU and display load, the cell voltage drops faster than the fuel gauge IC can track — the system hits the low-voltage protection threshold before the displayed percentage reaches zero. The fix is calibration: fully discharge to hibernate-cutoff under normal use load, then charge to 100% without interruption. After two full calibration cycles, the fuel gauge IC maps the new cell's actual discharge curve and the early shutdowns stop.

Replaces Part Numbers

B31N1902

Technical Specifications

Voltage11.52V
Amp Hours3550mAh
Capacity3550mAh
Rate40.9Wh
Net Weight170g /6.00 oz
Gross Weight430g /15.17 oz
Approximate Weight430g /15.17 oz
Dimension 270.60 x 72.30 x 6.00mm

Product Highlights

  • Brand: Asus
  • 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 Asus laptop shows 0% or "unknown" battery right after I put the new B31N1902 in — is the cell dead?

The cell is not dead. The BIOS fuel gauge IC is still reading EEPROM data from the old battery and hasn't mapped the new cell yet. Plug in AC power and leave it to charge uninterrupted to 100%, then run the laptop on battery alone until it hibernates. That one full cycle resets the learn cycle and the gauge corrects itself.

The battery Wh rating showing in Windows says 42Wh or higher, but the product lists 40.9Wh — which is right?

The figure Windows reports comes from the EEPROM on the cell, which stores the rated design capacity. The 40.9Wh on the product listing is the actual tested capacity at full charge. Minor differences between rated and real-world capacity are normal across lithium-polymer cells — the cell is not oversized or mismatched. The BIOS and charger both use voltage thresholds, not the Wh figure, so this difference does not affect charging or protection behaviour.

New B31N1902 cell stopped charging at 80% and won't go higher — is the battery faulty?

This is almost always a BIOS charge-limit setting, not a cell fault. Asus MyASUS and BIOS both include a battery health charge mode that caps charging at 60% or 80% to reduce long-term cell stress. Open MyASUS, go to Battery Health Charging, and switch the mode to Full Capacity. The cell will then charge to 100% on the next cycle.

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