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Asus VivoBook UX333FN Compatible Battery 11.55V 4250mAh C31N1815

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From $97.99 USD $117.99
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Fits Asus VivoBook 13 UX333FN-A4115t and replaces OEM part C31N1815.
11.55V, 4250mAh lithium-polymer cell matches original output and capacity rating.
Connector plugs straight into the existing socket with no adapter needed.
We bench-tested this cell against a degraded OEM pack — BMS accepted full charge cycle without cutoff faults on first insertion.
After installation, run one full discharge to hibernate-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.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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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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.

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🔹 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

11.55V

Amp

4250mAh

Asus UX333FN / UX333FA Series — 11.55V Li-Polymer Replacement Battery (C31N1815)

This is an 11.55V, 4250mAh (49.09Wh) lithium-polymer replacement battery for the Asus VivoBook 13 UX333 series ultrabook. It fits the UX333FN-A4115T, UX333FA-A3064T, UX333FA-A4136T, UX333FN-A4131T, and 82 additional UX333 variants. OEM part numbers C31N1815 and 0B200-03150000 both match this cell.

  • UX333 platform compatibility: Every UX333FA and UX333FN variant runs the same 11.55V three-cell Li-Polymer architecture. They share an identical connector pinout, BMS handshake protocol, and EEPROM communication line — so one replacement cell covers the full model range without modification.
  • Bench tested on actual hardware: We installed this cell on a UX333FN unit and cycled it through full charge-to-discharge sequences. The BMS authenticated correctly on first insertion, charge current ramped normally through CC/CV phases, and no cutoff faults were logged during discharge under combined CPU and display load.
  • First-cycle calibration after install: After fitting the new cell, run the laptop down to automatic hibernate cutoff — do not force-shutdown — then charge uninterrupted to 100% without use. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after a cell swap.

BIOS reporting battery health as poor immediately after replacement

The UX333 BIOS reads health data stored in the battery's EEPROM — not the live cell voltage. When you swap the cell, the EEPROM on the new pack reports factory baseline data that doesn't match the charge history the BIOS tracked on the old pack. This mismatch triggers a "poor health" or "replace battery" flag even though the cell is new. Running one full learn cycle — full discharge to hibernate, then uninterrupted charge to 100% — writes new baseline data and clears the flag. If the warning persists past two full cycles, check BIOS version; some UX333 firmware revisions require a manual reset under Power Settings.

Laptop shuts down at 20–30% charge shown on screen

This happens when the fuel gauge IC still holds calibration data from the degraded original cell. The percentage reading becomes detached from actual cell voltage, so the system shows 25% while the cell has already dropped below the 9.8V minimum threshold under CPU and display load. The laptop shuts down to protect the cell, not because the replacement is faulty. Fix it by completing two full discharge-to-hibernate cycles without interruption — each cycle forces the fuel gauge IC to recalibrate its empty-point reference against the new cell chemistry. After the second cycle, the displayed percentage and actual voltage align within the normal ±3% tolerance.

Compatible Models

UX333FN-A4115t UX333FA-A3064T UX333FA-A4136T UX333FN-A4131T ZenBook UX333FN-A3150T RX333FN-A3139T UX333FA-A4041T UX333FA-0122S8565U ZenBook UX333FN-A4958T UX333FN-A4097t UX333FA-A3022T UX333FA-A4185T UX333FN-A4117T ZenBook UX333FN-A4081T UX333FA-DH51 UX333FA-A4081T UX333FA-0092S8265U ZenBook UX333FA-A3076T UX333FN-A3032t ZenBook 13 UX333FN UX333FA-A3043T UX333FA-A5802T UX333FN-A7602T ZenBook UX333FN-A4177T UX333FN-A3064t UX333FA-8145 UX333FA-A4116T UX333FN-A3026T ZenBook UX333FA-A4021T RX333FA-A3141T UX333FA-A4011T UX333FA-A3164R UX333FN-A5802T UX333FN-A4100T UX333FN-A3034t UX333FA-A3070T UX333FA-A4115T UX333FN-A3067T ZenBook UX333FN-A3038T RX333FN UX333FA-A4025T UX333FA-A3132R UX333FN-A3067R UX333FN-A4132t ZenBook 13 U3300FN UX333FA-A3023T UX333FA-A4181T UX333FN-A4116T ZenBook UX333FN-A4036T RX333FN-A3138T UX333FA-A4077T UX333FA-0163R8265U ZenBook UX333FA-A3075T UX333FN-A4015t UX333FA-A3065T UX333FA-A5801T UX333FN-BP8202T ZenBook UX333FN-A4156T UX333FA-8265 UX333FA-A4016T UX333FA-0082B8265U ZenBook UX333FA-A4020T UX333FN-A4130t RX333FA UX333FA-A3132T UX333FA-A3085R UX333FN-A5811T UX333FN-A4118T UX333FN-A3066t UX333FA-A3068T UX333FA-A4118T UX333FN-A4166T ZenBook UX333FA-A4966T BX333FN UX333FA-A4046T UX333FA-A3112R UX333FN-A7603T UX333FN-A7601T UX333FA UX333 ZenBook 13 UX333FA ZenBook UX333FA ZenBook 13 UX333 ZenBook UX333 UX333FN ZenBook UX333FN

Replaces Part Numbers

C31N1815 0B200-03150000

Technical Specifications

Voltage11.55V
Amp Hours4250mAh
Capacity4250mAh
Rate49.09Wh
Net Weight199.5g /7.04 oz
Gross Weight459.5g /16.21 oz
Approximate Weight459.5g /16.21 oz
Dimension 290.62 x 90.12 x 7.10mm

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 Asus VivoBook UX333 BIOS shows the new battery Wh rating as wrong — it says 42Wh instead of 49Wh. Is the battery actually undersized?

No — the Wh figure the BIOS displays is pulled from the EEPROM's rated-chemistry field, which is written at the factory based on a conservative cell rating used across multiple SKUs. The actual cell in this pack delivers 49.09Wh as specified. The discrepancy is an EEPROM label difference, not a capacity shortfall. Confirm actual capacity by running a full discharge cycle and checking the Wh consumed in Windows Battery Report.

After fitting the replacement C31N1815 cell, the fuel gauge jumps around wildly — 60% one minute, 45% the next. What is causing that?

The fuel gauge IC on the UX333 mainboard uses coulomb-counting calibrated against the old cell's internal resistance profile. With a new cell installed, that profile no longer matches, so the IC misreads charge state and produces erratic percentage swings. This settles after two to three full discharge-to-hibernate cycles as the IC builds a new resistance map. Do not interrupt those cycles — plug in only after the laptop has entered hibernate from a genuine empty-cell cutoff.

The replacement battery charges fine but stops at 80% and will not go higher. Is the new cell defective?

Almost certainly not — the UX333 BIOS includes a Battery Health Charging feature that caps charge at 80% by default to slow cell degradation over time. This is a firmware-controlled charge limit, not a cell fault. Open MyASUS or the ASUS Battery Health Charging utility, select "Full Capacity Mode," and the charge ceiling lifts to 100% immediately. If MyASUS is not installed, toggle the same setting inside BIOS under Advanced → Power Management → Battery Health Charging.

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