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Asus UX31 C22-UX31 Replacement Battery 7.4V 6800mAh

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From $115.99 USD $139.99
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Fits Asus UX31, UX31A, and UX31A-R4004H ultrabooks; replaces OEM part number C22-UX31.
7.4V, 6800mAh Li-Polymer cell delivers 50.32Wh to restore full unplugged session length on this ultraportable.
Connector sits flush into the battery slot with single mechanical locking tab; no keying required.
We ran full charge cycles on UX31 hardware; BMS accepted the cell without fault codes and held voltage under sustained CPU load.
After installation, run one full discharge to shutdown then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears inaccurate health warnings that appear after cell swaps.
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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.

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.

Voltage

7.4V

Amp

6800mAh

Asus UX31 / UX31A Series — 7.4V Li-Polymer Replacement Battery (C22-UX31)

This is a 7.4V, 6800mAh (50.32Wh) Li-Polymer battery for the Asus UX31 and UX31A ultrabook. It replaces the OEM C22-UX31 cell when the original pack no longer holds a usable charge. Fits the UX31, UX31A, and UX31A-R4004H among 53 confirmed models in the series.

  • UX31 and UX31A compatibility: Both chassis use the same 7.4V two-cell Li-Polymer pack with an identical connector pinout and BMS handshake. The BIOS on both models reads cell state through the same SMBus protocol, so the same replacement cell satisfies both platforms without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a UX31A unit. The BMS accepted the new cell without error flags, reported correct voltage at each charge stage, and hit cutoff cleanly at the low-voltage threshold without tripping any unexpected protection events.
  • Post-install recalibration on the UX31: After fitting, run one full discharge down to the hibernate cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears after every cell swap on this platform.

BIOS reporting battery health as poor immediately after replacement

The UX31 BIOS stores battery health data from the previous cell in its EEPROM. When a new cell goes in, the BIOS compares the fresh cell against degraded historical data and flags the health as poor — even though the new cell is fine. This is not a fault with the replacement battery. One full discharge-to-hibernate followed by a full uninterrupted charge resets the learn cycle. After two to three full cycles, the BIOS recalibrates and the health warning clears.

UX31 shutting down at 20–30% charge remaining after battery swap

This happens because the fuel gauge IC is still calibrated against the old, degraded cell. It miscalculates the remaining capacity and sends a shutdown signal before the new cell is actually depleted. The cell voltage is hitting what the IC incorrectly reads as the low-voltage cliff. Run two to three full discharge-to-hibernate and full-recharge cycles to let the gauge IC map itself to the new cell's actual voltage curve. After calibration, the shutdowns stop and the percentage readout stabilises — confirm the fix by checking that resting voltage at reported 20% reads above 7.0V.

Compatible Models

UX31 UX31A UX31A-R4004H UX31 Ultrabook UX31E Ultrabook ZenBook UX31 ZenBook UX31E UX31E-DH72 UX31KI3517A Zenbook UX31A UX31e-xh72 Zenbook UX31A-R4003P UX31E-RY018X Zenbook UX31A-C4027H Zenbook UX31E-1A UX31E-DH52 UX31e-sh72 UX31E-RY010X Zenbook UX31A-C4032H UX31E-1C UX31e-ma1 X31E-RY029V Zenbook UX31A-R4002H Zenbook UX31E-RY008V UX31A-1A Zenbook UX31A-R4005V UX31e-xh71 Zenbook UX31A-R4003H Zenbook UX31E-RY010V UX31E-RY009V UX31A-2D UX31E-1A Zenbook UX31A-R4003V Zenbook UX31E-RY029V UX31E-RY010V Zenbook UX31A-C4029H UX31E-1B UX31E-DH53 UX31e-mt1 UX31E-RY024V Zenbook UX31A-C4033H Zenbook UX31E-1C Zenbook UX31A-R4005H UX31E-RY256S Zenbook UX31E-RY009V UX31E-RY003V UX31A-2A Zenbook UX31E-RY012V UX31E-RY012V Zenbook UX31A-R4003X Zenbook UX31A-R4004V Zenbook UX31A-R4002V UX31E-RSL8 UX31e-xh51 Zenbook UX31A-R4004H UX31A Ultrabook UX31E

Replaces Part Numbers

C22-UX31

Technical Specifications

Voltage7.4V
Amp Hours6800mAh
Capacity6800mAh
Rate50.32Wh
Net Weight301.9g /10.65 oz
Gross Weight561.9g /19.82 oz
Approximate Weight561.9g /19.82 oz
Dimension 317.00 x 131.92 x 7.90mm

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

Why does Windows show the Asus UX31 battery as "0% available (plugged in, not charging)" right after I installed the new cell?

The fuel gauge IC on the UX31 has lost its reference point because the old cell's data is gone and the new cell hasn't been mapped yet. The BIOS briefly reads the pack as unknown or empty while it initialises communication over SMBus. Plug in the charger, leave it connected for 15 minutes without interrupting power, then do a full discharge to hibernate and recharge to 100%. That sequence gives the IC enough data to lock onto the new cell and the 0% reading clears.

My UX31A is reporting 38Wh capacity in system info, but the replacement battery is rated 50.32Wh — is the cell wrong?

The lower Wh figure comes from EEPROM data the BIOS carried over from the worn-out original cell, which had degraded well below its rated capacity before you swapped it. The replacement cell itself is correct at 50.32Wh. Run two full discharge-to-hibernate and uninterrupted full-charge cycles — the BIOS learn cycle will overwrite the stale EEPROM value and the reported capacity will climb toward the actual rated figure.

The UX31 battery stops charging at 80% and never goes higher — is this a fault with the replacement cell?

This is almost always a BIOS-controlled charge limit, not a fault in the cell itself. Asus shipped several BIOS and battery health software versions for the UX31 series that cap charging at 80% when a battery conservation mode is active. Open MyASUS or the older ASUS Battery Health Charging utility, check whether "Balanced Mode" or "Maximum Lifespan Mode" is selected, and switch it to "Full Capacity Mode." The charge limit releases immediately and the battery will charge to 100% on the next cycle.

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