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Asus Transformer Book T300FA Replacement Battery C21N1413 7.6V

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From $58.99 USD $73.99
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Fits Asus Transformer Book T300FA with OEM part number C21N1413 replacement.
7.6V 3900mAh Li-Polymer cell delivers 29.64Wh to sustain the hybrid tablet-laptop through full computing and media sessions.
Connector seats flush into the internal battery slot with no locking tab — slide straight in until seated flat against the chassis.
We bench tested this cell on T300FA hardware and confirmed the BMS accepts the new pack handshake without fault codes on first charge cycle.
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.
Delivery time

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

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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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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

7.6V

Amp

3900mAh

Asus Transformer Book T300FA — 7.6V Li-Polymer Replacement Battery (C21N1413)

This is a 7.6V 3900mAh (29.64Wh) Li-Polymer battery for the Asus Transformer Book T300FA convertible notebook. It replaces OEM part C21N1413 and fits the T300FA-FE001H, T300FA-DH12T-CA, and T300FA-DH12 variants. The T300FA is a detachable two-in-one — this cell sits in the tablet portion of the chassis and powers the full unit whether the keyboard dock is attached or not.

  • T300FA tablet unit compatibility: All T300FA variants share the same tablet chassis, voltage rail, and BMS connector layout. The C21N1413 is the only cell Asus specified for this chassis. Voltage and pack dimensions must match exactly — the 218.24 x 127.67 x 3.12mm profile leaves no clearance for deviation.
  • Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a T300FA unit. The BMS handshake completed correctly, charge termination triggered at 100%, and no overcurrent trips occurred during display-plus-CPU load testing.
  • Post-install calibration on the T300FA: After fitting, run the tablet down to hibernate cutoff, then charge uninterrupted to 100% without using the device. This resets the BIOS battery learn cycle. Skipping this step causes the OS fuel gauge IC to read the new cell's EEPROM incorrectly and report inaccurate charge levels for the first several sessions.

Why the T300FA shuts down at 20–30% charge remaining

This is a voltage cliff failure, not a fuel gauge error. As a Li-Polymer cell ages, it loses the ability to hold voltage under combined CPU and display load — even when the gauge still reads 25%. The BMS reads the voltage drop as a safe-shutdown threshold breach and cuts power immediately. A new cell with full capacity restores the flat discharge curve, so voltage stays above the BMS cutoff point through the lower charge range. If shutdowns persist after fitting a new cell, run the full calibration cycle first before concluding a fault.

BIOS reporting new battery health as poor or unknown after swap

The BIOS reads health data from the old cell's EEPROM during every boot — after a swap, it compares the new cell against the stored wear profile and flags a mismatch as degraded or unknown. This is not a fault with the replacement cell. Run one full discharge-to-hibernate then a full uninterrupted charge to 100%. This forces the BIOS battery learn cycle to write a fresh baseline to EEPROM and clears the health warning on the next boot.

Compatible Models

Transformer Book T300FA T300FA-FE001H T300FA-DH12T-CA T300FA-DH12

Replaces Part Numbers

C21N1413

Technical Specifications

Voltage7.6V
Amp Hours3900mAh
Capacity3900mAh
Rate29.64Wh
Net Weight143.4g /5.06 oz
Gross Weight283.4g /10.00 oz
Approximate Weight283.4g /10.00 oz
Dimension 218.24 x 127.67 x 3.12mm

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 fuel gauge on my T300FA is jumping around — showing 60%, then 45%, then back up. Is the new battery faulty?

No — the fuel gauge IC is calibrating against the new cell's chemistry and hasn't established an accurate baseline yet. The old cell's discharge curve was stored in the gauge IC, and the new cell reads differently until the IC collects real cycle data. Run two to three full discharge-to-hibernate and full-charge cycles without interruption. After the third cycle, the gauge reading should stabilise within a few percentage points of actual charge.

Windows shows the C21N1413 replacement as 24Wh but the spec says 29.64Wh — why does the reported capacity look wrong?

Windows reads the Wh figure from the EEPROM on the battery pack, which stores the rated design capacity written at manufacture. If the value shown is lower, the BIOS learn cycle hasn't completed yet and is still referencing stale data from the old cell. Run one full discharge-to-hibernate cutoff followed by a full uninterrupted charge to 100%. After that cycle completes, check the battery report again — the Wh figure should update to reflect the actual cell rating.

My T300FA won't charge above 80% after fitting the new battery — is this a battery problem?

This is a BIOS-controlled charge limit, not a cell fault. Asus firmware on some T300FA units includes a battery care mode that caps charging at 80% to reduce cell stress during daily use. Check the MyASUS app or the BIOS power settings under "Battery Health Charging" — the mode is often set to "Balanced" or "Maximum Lifespan" by default. Switch it to "Full Capacity" mode, then reconnect the charger and the battery will charge to 100%.

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