Asus VivoBook F542UF Replacement Battery C21N1634 7.6V 4900mAh
Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.
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Asus VivoBook F542UF Replacement Battery C21N1634 7.6V 4900mAh - 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
⚠️ 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.
Asus VivoBook F542UF Replacement Battery C21N1634 7.6V 4900mAh - is backordered and will ship as soon as it is back in stock.
Voltage
7.6V
Amp
4900mAh
Asus VivoBook F542UF — 7.6V Li-Polymer Replacement Battery (C21N1634)
This is a 7.6V, 4900mAh (37.24Wh) Li-Polymer battery for the Asus VivoBook F542UF and related VivoBook variants including the R542UF and R542UQ series. It matches OEM part numbers C21N1634, C21PQCH, 0B200-02550000, and 0B200-02550200. Install it when the original cell no longer holds a usable charge or fails to power the laptop off mains.
- VivoBook F542 and R542 platform fit: These models share the same two-cell Li-Polymer pack format, 7.6V voltage rail, and SMBus BMS handshake. The connector and cell housing are physically identical across the F542UF, R542UF, and R542UQ variants, which is why one part number covers all of them.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a VivoBook F542UF unit. The BMS communicated state-of-charge data correctly over SMBus from the first cycle, and the ASUS battery management driver read capacity and cycle count without errors.
- First-cycle calibration on VivoBook: After fitting this cell, run the laptop on battery until it hibernates at low charge cutoff, then charge uninterrupted to 100%. This one full discharge-to-hibernate cycle resets the BIOS battery learn cycle and clears the inaccurate health warning that almost always appears after a cell swap on this platform.
Why the VivoBook F542UF shuts down at 20–30% shown after a battery swap
The fuel gauge IC on the F542UF learns discharge curves from the previous cell and stores them in EEPROM. When a new cell is installed, the IC is still referencing the old cell's end-of-life voltage floor, so it miscalculates the remaining capacity. Under full CPU and display load, the new cell hits the IC's stale cutoff threshold before the gauge reaches zero. Running two to three complete discharge-to-hibernate cycles recalibrates the fuel gauge IC against the new cell's actual voltage curve and eliminates the early shutoff.
BIOS reporting battery health as "poor" or "replace battery" immediately after fitting a new cell
This warning is driven by EEPROM data carried over from the old cell, not a fault in the new one. The Asus BIOS reads cycle count and state-of-health flags from the battery's SMBus EEPROM, and a degraded old cell leaves behind unfavourable values that persist after the swap. The fix is straightforward: complete one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100%. After that charge completes, the BIOS battery learn cycle refreshes the stored health data and the warning clears — confirm by checking MyAsus or BIOS Battery Information at 100% charge.
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 F542UF shows the new battery as "0%" or "unknown" in Windows immediately after fitting — is the cell dead?
No — this is the fuel gauge IC reading stale EEPROM data from the old cell before it has run a calibration cycle. Plug in the charger and let it charge uninterrupted to 100%. Windows Battery report should then show correct capacity. If it still reads 0% after a full charge, reseat the connector and confirm the SMBus pins are fully engaged.
Windows is reporting 37Wh but the system info screen shows a different Wh rating than what I expected — which is correct?
The 37.24Wh figure from the cell's own EEPROM is the accurate rated value for this pack. Some Asus system info screens pull a cached Wh figure from a firmware table rather than live EEPROM, which can show a mismatched number for the first few cycles. After one or two full charge-discharge cycles the SMBus data settles and the system info readout aligns with the cell's actual 37.24Wh rating.
The F542UF stops charging at 80% and won't go higher — what's causing that?
This is a BIOS-controlled charge limit, not a fault in the replacement cell. Asus ships many VivoBook models with Battery Health Charging enabled in MyAsus, which caps charging at 80% to reduce long-term cell wear. Open MyAsus, go to Battery Health Charging, and switch the mode from "Balanced" or "Maximum Lifespan" to "Maximum Capacity" — the battery will then charge to 100%.
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