A42-W1 Asus W1 Replacement Battery 14.8V 4400mAh
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A42-W1 Asus W1 Replacement Battery 14.8V 4400mAh - 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.
A42-W1 Asus W1 Replacement Battery 14.8V 4400mAh - is backordered and will ship as soon as it is back in stock.
Voltage
14.8V
Amp
4400mAh
Asus W1 Series — 14.8V Li-ion Replacement Battery (A42-W1)
The A42-W1 is a 14.8V, 4400mAh (65.12Wh) Li-ion battery for the Asus W1 notebook line. It fits the W1, W1G, W1Ga, and W1Gc, along with additional W1-series variants. When the original cell no longer holds a charge, this unit restores portable operation without hardware modification.
- W1-series cell compatibility: All W1-series notebooks share the same 14.8V four-cell architecture and connector pinout. The BMS on each model expects the same voltage rail and communication protocol, so one cell swap covers the full W1 range without adapter or firmware workaround.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on W1-series hardware. The BMS handshake completed correctly, charge acceptance reached rated capacity, and no false over-temperature cutoffs triggered during load testing.
- First-cycle recalibration on the W1: After installation, run the notebook down to hibernate cutoff on battery alone, then charge uninterrupted to 100% before use. This forces the W1's fuel gauge IC to learn the new cell's actual capacity curve and clears the inaccurate health warning the BIOS flags after every cell swap.
Why the W1 BIOS flags poor battery health immediately after a cell swap
The Asus W1 stores historical charge data in EEPROM on the battery's protection circuit. When a new cell arrives, that EEPROM either holds default values or data mismatched to the old unit. The BIOS reads this data at POST and flags the battery as degraded before a single charge cycle has run. One full discharge-to-hibernate followed by an uninterrupted charge to 100% rewrites the learn cycle data and clears the warning. After two to three full cycles, the BIOS health reading stabilises.
W1 shutting down at 20–30% charge remaining
This happens when the fuel gauge IC has not yet calibrated against the new cell's voltage curve. The IC is still using the old cell's discharge profile, so it misreads the voltage cliff and signals a low-battery shutdown early. It is not a cell fault. Run two or three full discharge-and-charge cycles without interruption to let the IC map the new curve accurately. After calibration, the gauge tracks remaining charge correctly and the early shutdowns stop. Confirm the cell voltage reads above 14.0V at the point the shutdown previously triggered.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Asus
- Manufacturer: CS
- Series: Standard
- Color: Silver
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The Asus W1 BIOS is showing the new battery as 0% health — did I get a bad cell?
No — this is an EEPROM mismatch, not a faulty cell. The W1's protection circuit carries stored charge history, and the BIOS reads that data at POST before the new cell has run a single cycle. Run the laptop down to hibernate cutoff on battery power alone, then charge uninterrupted to 100%. That resets the learn cycle and the health reading corrects itself within two to three full cycles.
My W1 shows 65Wh in the battery specs tab but the system info panel is reporting a different Wh figure — which is right?
The system info panel reads the EEPROM-stored rated value from the protection circuit, which may reflect the factory default rather than the actual cell chemistry. The physical cell in this battery is rated at 65.12Wh. After the fuel gauge IC completes two or three full calibration cycles, the reported figure will converge closer to actual capacity. If the panel still shows a mismatched value after calibration, check the W1's power management settings — some BIOS versions cap the reported design capacity independently of the cell.
The W1 fuel gauge is jumping around wildly — showing 80% one minute, then 45% the next — is this a BMS fault?
This is a fuel gauge IC calibration issue, not a BMS fault. The IC is interpolating charge state from a voltage curve it built around the old cell, and the new cell's discharge profile is different enough to cause erratic readings. We saw this same behaviour on the bench during the first cycle after installation. Run two full discharge-to-hibernate and charge-to-100% cycles without interruption, and the IC remaps the curve against the actual cell. The gauge stabilises after that — confirm by checking that the voltage reads between 14.4V and 16.8V across the normal operating range.
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