Asus UX431 Replacement Battery C21N1833 7.7V 6000mAh
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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Asus UX431 Replacement Battery C21N1833 7.7V 6000mAh - 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 UX431 Replacement Battery C21N1833 7.7V 6000mAh - is backordered and will ship as soon as it is back in stock.
Voltage
7.7V
Amp
6000mAh
Asus UX431 / VivoBook S14 Series — 7.7V Li-Polymer Replacement Battery (C21N1833)
This is a 7.7V, 6000mAh (46.2Wh) Li-Polymer replacement battery for the Asus UX431 and VivoBook S14 ultrabook range. It fits the UX431FA, UX431FA-AM022T, S431FL-AM041T, and over 139 additional variants sharing the same OEM part number C21N1833 or 0B200-03340000. The slim 5mm profile matches the original cell envelope for the UX431's thin chassis.
- UX431 and VivoBook S14 platform fit: These models share a common power rail, connector pinout, and BMS handshake protocol tied to the C21N1833 spec. The replacement cell carries the same communication data the EC chip expects, so the system recognises it without rejecting it at the firmware level.
- Bench tested on actual hardware: We ran this cell on a UX431FA and monitored BMS communication through the charge and discharge cycle. The fuel gauge IC picked up the new cell without error codes, and the charge controller stepped through CC/CV stages correctly to full capacity.
- Post-swap calibration on the UX431: After fitting, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after swapping cells in this platform.
BIOS reporting battery health as poor immediately after fitting the new cell
The UX431 BIOS reads health status from EEPROM data stored on the battery's fuel gauge IC. A new cell ships with factory-default EEPROM values that don't match the system's learned baseline from the old battery. The EC chip flags this as degraded health — it's a data mismatch, not a cell fault. Running a single full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the learn cycle to rewrite those values against the new cell.
UX431 shutting down hard at 20–30% charge shown on screen
This happens when the cell voltage drops below the BMS cutoff threshold under combined CPU and display load before the OS fuel gauge reaches 0%. The fuel gauge IC is reading state-of-charge from a calibration curve built against the old cell — it hasn't recalculated the voltage cliff for the new one yet. The result is an abrupt shutdown while Windows still shows charge remaining. After two full discharge-and-charge calibration cycles, the gauge IC recalibrates the curve and the cutoff aligns with the displayed percentage.
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
Windows shows the new Asus UX431 battery as "0% available (plugged in, charging)" and it never moves — what's wrong?
The fuel gauge IC on the new cell hasn't synchronised with the system's charge counter yet. This is an EEPROM initialisation state, not a charging fault. Let the battery charge uninterrupted to 100% with the laptop off or in sleep, then complete one full discharge to hibernate cutoff. After that cycle, the OS fuel gauge reads correctly.
The UX431 BIOS shows the replacement cell's Wh rating as lower than the original — is the battery underspec?
The Wh figure the BIOS displays is pulled from the EEPROM on the fuel gauge IC, which ships with a rated value tied to the cell's factory calibration state, not its measured capacity on your specific unit. The actual stored energy in this 46.2Wh cell is correct to spec. Run one full discharge-to-hibernate and recharge cycle — the BIOS value updates once the fuel gauge IC recalculates from a real discharge curve.
The new battery on the VivoBook S14 S431FL stops charging at exactly 80% and won't go higher — is the cell faulty?
This is a BIOS-controlled charge limit, not a cell fault. Asus enables a battery health charging mode on the VivoBook S14 platform that caps charge at 80% to reduce cell stress during extended plugged-in use. Go to MyASUS or the ASUS Battery Health Charging app, select the "Full Capacity" mode, and the charge limit clears immediately.
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