Asus VivoBook 4000 Compatible Battery C21N1408 7.6V 4700mAh
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Asus VivoBook 4000 Compatible Battery C21N1408 7.6V 4700mAh - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Asus VivoBook 4000 Compatible Battery C21N1408 7.6V 4700mAh - is backordered and will ship as soon as it is back in stock.
Voltage
7.6V
Amp
4700mAh
Asus VivoBook V555L / MX555 / 4000 Series — 7.6V Li-Polymer Replacement Battery (C21N1408)
This is a 7.6V, 4700mAh (35.72Wh) Li-Polymer replacement battery for the Asus VivoBook 4000, V555L, MX555, A555LJ, and related models. It replaces OEM part numbers C21N1408, 0B200-01130100, and 0B200-01130300. If your VivoBook no longer holds a charge or powers off unexpectedly, this cell is the direct swap.
- VivoBook V555 / MX555 / 4000 platform fit: These models share the same two-cell Li-Polymer pack format, 7.6V nominal voltage rail, and connector pinout. The BMS handshake protocol is consistent across this generation, so the replacement cell is recognised without any firmware workaround.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a VivoBook V555L unit. The BMS accepted the new cell without fault codes, and the protection circuit responded correctly to overcharge and over-discharge cutoff thresholds.
- First-cycle calibration after install: After fitting this cell, run a full discharge to the hibernate cutoff point, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after swapping cells on this platform.
BIOS reporting poor battery health after fitting a new C21N1408 cell
When a new cell goes in, the BIOS still holds EEPROM data from the old pack — cycle count, learned capacity, and health flags. The system compares the new cell's output against stale reference values and flags it as degraded before it has been through a single cycle. This is not a fault with the replacement cell. Run one complete discharge-to-hibernate followed by a full uninterrupted charge, and the BIOS will rewrite those values against the new cell's actual behaviour.
VivoBook shutting down at 20–30% charge shown on screen
The fuel gauge IC calibrates against cell behaviour over several cycles. After a swap, the IC is still working from the old cell's discharge curve, so it misreads the remaining capacity. When the new cell hits a voltage the IC hasn't mapped yet, the system interprets it as empty and cuts power — even though the percentage shown still reads 20–30%. The fix is two to three full discharge-and-charge cycles so the IC relearns the curve. After calibration, shutdowns should stop above 5% and the percentage readout will track accurately. Confirm calibration is complete when the laptop reaches hibernate at a consistent voltage near 6.8V per cell.
Compatible Models
Replaces Part Numbers
Technical Specifications
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 VivoBook shows "0% available (plugged in, charging)" and the battery percentage never moves — is the new cell faulty?
This is almost always the BIOS reading stale EEPROM data from the old pack rather than a fault with the new cell. The BIOS locked onto the old battery's communication data and hasn't yet recognised the replacement. Perform a full discharge to hibernate, remove the charger, hold the power button for 15 seconds, then charge uninterrupted to 100%. If the gauge still reads 0% after one complete cycle, reseat the battery connector and repeat.
Windows is reporting 35Wh but the battery info tool shows a different design capacity — which number is right?
The rated design capacity in Windows comes from EEPROM data written to the BMS chip — it reflects the chemistry rating, not a live measurement. The 35.72Wh figure in our product data is the actual cell specification for this C21N1408 replacement. Small discrepancies between what Windows reports and the label spec are normal until the fuel gauge IC completes two or three calibration cycles against the new cell's discharge curve. After calibration cycles, the reported full-charge capacity will converge toward 35Wh.
The new battery won't charge past 80% on the VivoBook — is something wrong with the cell?
An 80% charge ceiling on Asus laptops is a BIOS-controlled feature called Battery Health Charging, active by default on many VivoBook models. The cell itself is not at fault. Open MyASUS or ASUS Battery Health Charging in Windows settings and switch the mode from "Balanced" or "Maximum Lifespan" to "Maximum Performance" — this lifts the cutoff to 100%.
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