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Asus VivoBook 14 B9450FA Replacement Battery 7.7V 4155mAh

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From $60.99 USD $75.99
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Fits Asus VivoBook 14 B9450FA and ExpertBook B9 B9450FA models replacing OEM part C21N1903.
This 7.7V 4155mAh Li-Polymer cell delivers 31.99Wh — enough capacity to sustain the ultrabook through a full workday without throttling.
Connector slides straight into the slot along the chassis edge with a single locking tab; orientation is marked on the pack itself.
We bench-tested the cell against the B9450FA motherboard; the BMS registered correctly on first insertion with no charge faults or cutoff errors.
After installation, run one full discharge to hibernation then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears false health warnings.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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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.

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🔹 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

7.7V

Amp

4155mAh

Asus ExpertBook B9450FA — 7.7V Li-Polymer Replacement Battery (C21N1903)

This 7.7V 4155mAh (31.99Wh) Li-Polymer cell replaces the original C21N1903 battery in the Asus ExpertBook B9450FA and its variants, including the BM0165R and BM0280R configurations. The B9450FA is an ultrabook built around portability, so battery health directly affects how long it stays off the charger. Voltage and connector match the OEM spec — no adapter or modification needed.

  • B9450FA platform compatibility: The B9450FA, B9450F, and their variant suffixes all share the same 7.7V two-cell Li-Polymer pack format with identical connector pinout and BMS handshake protocol. That is why one part number — C21N1903 — covers the full range.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on a B9450FA unit, confirmed the BMS accepted the handshake without fault codes, and verified the fuel gauge IC began reporting charge state correctly after two full calibration cycles.
  • First-cycle reset after install: After fitting this cell, run the laptop down to hibernate cutoff on a normal workload, then charge it uninterrupted to 100%. This gives the BIOS battery learn cycle a clean baseline and clears the inaccurate health warning that appears after any cell swap.

Why the B9450FA BIOS flags a new cell as poor health immediately after replacement

The BIOS reads stored EEPROM data from the previous pack to assess health. When a new cell goes in, that EEPROM data is gone, so the system has no learned charge curve to reference and defaults to a degraded-health flag. This is not a fault with the replacement cell. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% gives the BIOS enough data to rebuild its learn cycle and clear the warning. After two to three cycles, the reported health figure stabilises.

Laptop shuts down at 20–30% shown on the charge indicator

This symptom appears when the fuel gauge IC is still calibrated against the old cell's discharge curve. Under combined CPU and display load, actual cell voltage drops faster than the gauge predicts, hitting the BMS low-voltage cutoff before the displayed percentage reaches zero. The fix is calibration — discharge fully to hibernate, then charge to 100% without interruption, twice. After two complete cycles, the fuel gauge IC maps the new cell's actual voltage curve and the premature shutdowns stop.

Compatible Models

B9450FA ExpertBook B9 B9450FA-BM0165R ExpertBook B9 B9450FA-BM0280R B9450F ExpertBook B9 B9450FA ExpertBook B9 B9450FA-BM0193R B9450

Replaces Part Numbers

C21N1903 0B200-03560000

Technical Specifications

Voltage7.7V
Amp Hours4155mAh
Capacity4155mAh
Rate31.99Wh
Net Weight130g /4.59 oz
Gross Weight270g /9.52 oz
Approximate Weight270g /9.52 oz
Dimension 232.00 x 103.70 x 5.00mm

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

The B9450FA BIOS shows my new battery as 0% or "unknown" right after I installed it — is the cell dead?

No — the BIOS lost the EEPROM data it had stored from the old pack and has nothing to read yet. Power the laptop on, let it run down to hibernate cutoff under normal use, then charge uninterrupted to 100%. That single full cycle gives the BIOS enough data to recognise and report the new cell correctly. Most users see normal percentage reporting within two cycles.

Windows is showing the wrong Wh rating for this battery in Device Manager — it says something different from 31.99Wh.

The figure Windows reads comes from the EEPROM embedded in the old pack's firmware, not live cell measurement. After a cell swap, the fuel gauge IC reports the previous pack's rated Wh until it completes at least one full calibration cycle. Run the laptop to hibernate cutoff once, charge fully to 100%, and Windows will recalculate the Wh figure against the actual new cell. If the number still looks off after two cycles, check BIOS battery settings — some B9450FA firmware versions have a stored design capacity value that updates only after a completed learn cycle.

My B9450FA stops charging at 80% and won't go higher — did I get a faulty battery?

This is almost always a BIOS charge-limit setting, not a cell fault. Asus firmware on the ExpertBook B9 series includes a battery care mode that caps charging at 80% to reduce long-term cell stress — it ships enabled on some units. Go to MyASUS or the BIOS power settings, locate Battery Health Charging, and switch from Balanced or Maximum Lifespan mode to Full Capacity mode. The cell will charge to 100% once that setting is changed.

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