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Asus A42-UL30 14.8V Replacement Battery 4400mAh Li-ion

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From $112.99 USD $135.99
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Fits Asus UL30Vt, UL30, UL30A and related models replacing OEM part A42-UL30, A42-UL50, A42-UL80.
14.8V 4400mAh lithium-ion cell delivers 65.12Wh to sustain processor and display load on ultraportable notebooks without AC power.
Connector slides onto the battery slot with a single locking tab — orientation is fixed, no reverse-insertion risk on this platform.
We bench-tested this cell in a UL30Vt under full CPU and GPU load; the BMS delivered steady 14.8V until cutoff, no early sag or throttling events.
After installation, run one full discharge to hibernation then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears false health warnings that appear after every cell swap.
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

14.8V

Amp

4400mAh

Asus UL30Vt Series — 14.8V Li-ion Replacement Battery (A42-UL30)

This is a 14.8V, 4400mAh (65.12Wh) Li-ion replacement battery for the Asus UL30Vt and its close variants. It fits the UL30, UL30A, and UL30A-A1 among others using the A42-UL30, A42-UL50, or A42-UL80 OEM part numbers. The connector and cell count match the original pack so the BIOS reads the battery correctly on first boot.

  • UL30 series compatibility: The UL30, UL50, and UL80 lines share a common four-cell 14.8V battery bay and the same BMS communication protocol. That is why one part number — A42-UL30 — covers all three sub-families. The EEPROM data embedded in this pack matches what the Asus EC firmware expects to see at handshake.
  • Bench tested on actual hardware: We ran this pack on a UL30A through a full charge and load cycle. The BMS held charge termination at 16.8V as expected, and the fuel gauge IC reported capacity within normal variance. No false low-battery shutdowns triggered during the test.
  • First-cycle reset for UL30Vt: After fitting this battery, discharge the laptop to hibernate cutoff under normal use, then charge uninterrupted to 100% without using the machine. This gives the UL30Vt's battery learn cycle a clean baseline and clears the inaccurate health warning that appears after every cell swap.

Why the UL30Vt BIOS flags a new battery as poor health

The Asus EC firmware reads health data from the pack's EEPROM, not from live cell measurements. A new cell ships with cycle count and wear data zeroed out, which the BIOS interprets as a mismatch against the original battery's stored profile. This produces a "battery not detected" or "poor health" warning on first boot even when the pack is electrically sound. Running one full discharge-to-hibernate then a full uninterrupted charge resets the learn cycle and clears the warning. If it persists after two full cycles, check the BIOS is on the latest firmware version.

UL30Vt shutting down at 20–30% charge shown

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The gauge was trained on the old, degraded cell, so it miscalculates the voltage cliff point on the replacement. Under full CPU plus display load the new cell's voltage drops faster than the gauge predicts, triggering an emergency shutdown before the displayed percentage reaches zero. Two to three full discharge-and-charge cycles recalibrate the gauge. After the third cycle, the cutoff should stabilise at or below 5% displayed charge, around 14.4V under load.

Compatible Models

UL30Vt UL30 UL30A UL30A-A1 UL30A-A2 UL30A-A3B UL30A-X1 UL30A-X2 UL30A-X3 UL30A-X4 UL30A-X5 UL30A-QX130X UL30A-QX131X UL50 UL50AG-A2 UL50Ag-A3B UL50Vg UL50Vg-A2 UL50VS-A1B UL50Vt UL50Vt-A1 UL50Vt-X1 UL50Vt-XX009X UL50Vt-XX010x UL80 Asus UL80Ag-A1 UL80Vt UL80Vt-A1 UL80Vt-WX009X UL80Vt-WX010X

Replaces Part Numbers

A42-UL30 A42-UL50 A42-UL80

Technical Specifications

Voltage14.8V
Amp Hours4400mAh
Capacity4400mAh
Rate65.12Wh
Net Weight380.7g /13.43 oz
Gross Weight650.7g /22.95 oz
Approximate Weight650.7g /22.95 oz
Dimension 271.38 x 50.41 x 27.01mm

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 UL30Vt shows the replacement battery as "0% available (plugged in, charging)" and it never moves — what's wrong?

The fuel gauge IC on the UL30's mainboard is still holding calibration data from the old cell. It has no valid reference point for the new pack's discharge curve yet, so it reports 0% even while charging. Charge the battery to 100% uninterrupted, then let the laptop discharge fully to hibernate cutoff under normal use. Repeat that cycle twice more and the gauge will lock onto the new cell's profile.

The UL30Vt system info panel is showing the wrong Wh rating — 48Wh instead of 65Wh — after fitting this battery. Is the pack faulty?

The Wh figure displayed in Windows or the BIOS is pulled from the EEPROM data stored in the battery pack, not calculated live from the cells. Some replacement packs ship with EEPROM values that reflect a lower-rated variant of the same cell family. The actual chemistry and capacity are correct — this is a data label difference, not a cell fault. Run a full learn cycle and the OS power manager will update its estimate to match real-world discharge behaviour.

Charge stops at 80% on the UL30A and the laptop will not charge past that point — is this a battery fault?

Asus includes a Battery Health Charging mode in the MyASUS or AI Charging utility, and it is sometimes enabled by default after a battery swap. This firmware-level cap holds charge at 80% to reduce long-term cell stress — it is not a fault in the replacement pack. Open MyASUS or the Battery Health Charging option in Windows settings and set the mode to Full Capacity. Charging will resume to 100% on the next cycle.

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