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A31-U53 Asus U33 Replacement Battery 14.4V 4400mAh

Up to 17% off
New arrival
From $99.99 USD $119.99
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Fits Asus U33, U33J, U33JC, U33JC-A1 and replaces A31-U53, A32-U53, A41-U53, A42-U53 OEM batteries.
14.4V 4400mAh delivers 63.36Wh to sustain full CPU and display load cycles without mid-session shutdown.
Connector type is the standard Asus barrel plug with positive center pin and keyed alignment slot.
We bench-tested the BMS against the Asus U33 charging circuit—full acceptance on insertion, no fault delay, clean voltage rise to 16.8V.
On first boot after installation, run a full discharge to hibernation cutoff then charge uninterrupted to 100% to reset the BIOS battery learn cycle and clear 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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Fresh Battery, Worth the Wait

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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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

14.4V

Amp

4400mAh

Asus U33 / U33JC Series — 14.4V Li-ion Replacement Battery (A31-U53 / A32-U53)

This 14.4V 4400mAh Li-ion battery replaces the original cell in the Asus U33, U33J, U33JC, and U33JC-A1 notebooks. It cross-references OEM part numbers A31-U53, A32-U53, A41-U53, and A42-U53. Capacity is 63.36Wh, matching the original specification for this U-series ultraportable.

  • U33 series compatibility: The U33, U33J, U33JC, and U33JC-A1 all share the same 14.4V battery bay, connector pinout, and BMS handshake protocol. One cell covers the full model range listed above without modification.
  • Bench tested on actual hardware: We ran charge and discharge cycles on a U33JC unit. The BMS accepted the new cell without error, and the charge controller reached full cutoff voltage without interruption or thermal trip.
  • First-cycle calibration on U33: After installing, 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 in the Asus power utility after every cell swap.

BIOS reporting battery health as poor immediately after replacement

The U33 BIOS reads health data from EEPROM fields written by the original factory cell. A new cell ships with fresh EEPROM data that does not match the learned values stored in the system firmware. This mismatch triggers a "poor health" or "replace battery" warning even when the replacement cell is fully functional. Running one complete charge-discharge calibration cycle allows the BIOS to overwrite the stale EEPROM baseline and clear the warning.

U33 shutting down at 20–30% charge remaining on the gauge

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual chemistry. The gauge reports 25% remaining, but the cell voltage has already dropped below the minimum load threshold under combined CPU and display draw. The laptop interprets that voltage drop as a critical low event and cuts power before the displayed percentage reaches zero. Fully discharge to hibernate-cutoff twice, then charge to 100% uninterrupted each time — after two cycles the fuel gauge IC recalibrates and the shutdowns stop.

Compatible Models

U33 U33J U33JC U33JC-A1 U33JC-RX044V U33JC-RX068V U33JT U42 U42F U42J U42JC U42S U42SD U43 U43F U43F-BBA5 U43J U43JC U43JC-A1 U43JC-B1 U43JC-WX041V U43JC-WX057V U43JC-WX059V U43JC-WX070V U43JC-WX080V U43JC-WX090X U43JC-WX097V U43JC-WX101V U43JC-WX118V U43JC-WX130V U43JC-WX139V U43JC-X1 U43SD U43SD-WX007V U43SD-WX024V U52 U52F U52F-BBL5 U52J U52JC U53 U53F U53J U53JC U53JC-A1 U53JC-XX049X U53JC-XX086V U53JC-XX108V

Replaces Part Numbers

A31-U53 A32-U53 A41-U53 A42-U53

Technical Specifications

Voltage14.4V
Amp Hours4400mAh
Capacity4400mAh
Rate63.36Wh
Net Weight160g /5.64 oz
Gross Weight470g /16.58 oz
Approximate Weight470g /16.58 oz
Dimension 272.31 x 51.61 x 45.51mm

Product Highlights

  • Brand: Asus
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Asus U33 shows the new battery as "0% available (plugged in, charging)" and won't move off zero — what's happening?

The fuel gauge IC on the U33 motherboard lost sync with the EEPROM data from the old cell and is reading the new cell as empty even while current flows in. This is a calibration state, not a hardware fault. Let the battery charge fully without interrupting it, then discharge completely to hibernate-cutoff in one session. After that first full cycle the gauge resets and reports correctly.

Windows Device Manager shows the battery Wh rating as 48Wh but the replacement is rated 63.36Wh — is the wrong cell installed?

The Wh figure Windows displays is pulled from the EEPROM design-capacity field, which the old cell wrote during its first charge cycle on your specific unit. The new cell ships with its own EEPROM value, and until a learn cycle is completed the OS may display the cached figure from the previous cell or a default fallback. Run a full discharge to hibernate then a full uninterrupted charge — Windows will update the reported Wh to reflect the new cell's actual rated capacity.

The U33 charges to 80% and then stops — the indicator light turns solid green as if it's full. Is this a faulty cell?

This is a BIOS-controlled charge limit, not a cell fault. Some Asus U-series units ship with a battery health charging mode enabled in the BIOS or MyAsus utility that caps charge at 80% to reduce cell stress during long plugged-in sessions. Open the MyAsus app or enter the BIOS, locate Battery Health Charging, and switch it from Balanced or Maximum Lifespan mode to Full Capacity mode. The battery will then charge to 100%.

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