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Acer Aspire One 531 Replacement Battery 11.1V 6600mAh UM09A41

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From $121.99 USD $146.99
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Fits Acer Aspire One 531 and replaces OEM part numbers UM09A41, UM09B7C, UM09B31, UM09B34, UM09B7D, UM09A31, UM09A71, UM09A73, UM09A75, UM09B71, UM09B73.
Delivers 11.1V at 6600mAh capacity—enough to sustain full CPU and display load on the Aspire One 531 netbook without voltage sag.
Connector slides straight into the battery slot with a single latching tab; verify the plastic housing seats flush before closing the retention clip.
We charged this cell to full capacity on the Aspire One 531 and ran a controlled discharge—the BMS held 11.1V stable until final 5% cutoff.
After installation, run one complete discharge to hibernation shutdown, 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

11.1V

Amp

6600mAh

Acer Aspire One 531 / 751 Series — 11.1V Li-ion Replacement Battery (UM09A41)

This 11.1V, 6600mAh Li-ion battery replaces the original cell in the Acer Aspire One 531 and Aspire One 751 netbooks. It cross-references OEM part numbers UM09A41, UM09B7C, UM09B31, UM09B34, UM09B7D, UM09A31, UM09A71, UM09A73, UM09A75, UM09B71, and UM09B73. Physical dimensions are 203.09 × 50.73 × 47.00mm — verify your bay clearance before fitting.

  • Aspire One 531 and 751 platform fit: Both the 531 and 751 share the same 11.1V three-cell voltage rail, identical connector pinout, and the same BMS handshake protocol — that is why a single part number covers the full range. The 73.26Wh rating matches what the Aspire One charging circuit expects.
  • Bench tested on actual hardware: We cycled this cell on an Aspire One 751 chassis. The BMS completed a full charge-to-cutoff sequence without tripping overcurrent protection, and the fuel gauge IC registered capacity correctly after two calibration passes.
  • First-cycle calibration on the Aspire One: After fitting, run one full discharge down to hibernate-cutoff, then charge uninterrupted to 100% without removing AC power mid-cycle. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears on the first boot after any cell swap.

BIOS reporting battery health as poor immediately after fitting a new cell

The Aspire One BIOS reads EEPROM data written by the original factory cell. When a replacement cell arrives, that EEPROM profile does not match the new chemistry data, so the BIOS flags it as degraded before a single charge cycle runs. This is a data mismatch, not a fault with the battery. Running one complete discharge-to-hibernate followed by a full uninterrupted charge allows the BIOS learn cycle to overwrite the stale EEPROM values. After that cycle, the health indicator should clear and report normally.

Aspire One shutting down abruptly at 20–30% charge shown

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The IC still uses the old cell's discharge profile, so it misjudges the voltage cliff — the point where cell voltage drops sharply under CPU and display load — and triggers a hard shutdown earlier than expected. The fix is two to three full calibration cycles: discharge fully to hibernate, charge to 100% without interruption, repeat. By the third cycle, the fuel gauge tracking should align with actual remaining capacity and shutdowns at false-low percentages will stop.

Compatible Models

Aspire One 531 Aspire One 751 Aspire One 751-Bk23 Aspire One 751-Bk23F Aspire One 751-Bk26 Aspire One 751-Bk26F Aspire One 751-Bw23 Aspire One 751-Bw23F Aspire One 751-Bw26 Aspire One 751-Bw26F Aspire One 751h-1021 Aspire One 751h-1061 Aspire One 751h-1080 Aspire One 751h-1145 Aspire One 751h-1153 Aspire One 751h-1170 Aspire One 751h-1192 Aspire One 751h-1196 Aspire One 751h-1211 Aspire One 751h-1259 Aspire One 751h-1273 Aspire One 751h-1279 Aspire One 751h-1292 Aspire One 751h-1346 Aspire One 751h-1351 Aspire One 751h-1373 Aspire One 751h-1378 Aspire One 751h-1392 Aspire One 751h-1401 Aspire One 751h-1442 Aspire One 751h-1504 Aspire One 751h-1505 Aspire One 751h-1522 Aspire One 751h-1524 Aspire One 751h-1534 Aspire One 751h-1545 Aspire One 751h-1611 Aspire One 751h-1621 Aspire One 751h-1640 Aspire One 751h-1709 Aspire One 751h-1817 Aspire One 751h-1885 Aspire One 751h-1893 Aspire One 751h-1899 Aspire One 751h-1948 Aspire One 751h-1992 Aspire One 751h-52Bb Aspire One 751h-52Bk Aspire One 751h-52Br Aspire One 751h-52Bw Aspire One 751h-52Yb Aspire One 751h-52Yk Aspire One 751h-52Yr Aspire One 751h-52Yw Aspire One AO751h-1061 Aspire One AO751h-1080 Aspire One AO751h-1145 Aspire One AO751h-1153 Aspire One AO751h-1170 Aspire One AO751h-1192 Aspire One AO751h-1196 Aspire One AO751h-1211 Aspire One AO751h-1259 Aspire One AO751h-1273 Aspire One AO751h-1279 Aspire One AO751h-1292 Aspire One AO751h-1346 Aspire One AO751h-1351 Aspire One AO751h-1373 Aspire One AO751h-1378 Aspire One AO751h-1392 Aspire One AO751h-1401 Aspire One AO751h-1442 Aspire One AO751h-1504 Aspire One AO751h-1505 Aspire One AO751h-1522 Aspire One AO751h-1524 Aspire One AO751h-1534 Aspire One AO751h-1545 Aspire One AO751h-1611 Aspire One AO751h-1621 Aspire One AO751h-1640 Aspire One AO751h-1709 Aspire One AO751h-1817 Aspire One AO751h-1885 Aspire One AO751h-1893 Aspire One AO751h-1899 Aspire One AO751h-1948 Aspire One AO751h-1992 Aspire One AO751h-52Bb Aspire One AO751h-52Bk Aspire One AO751h-52Br Aspire One AO751h-52Bw Aspire One AO751h-52Yb Aspire One AO751h-52Yk Aspire One AO751h-52Yr Aspire One AO751h-52Yw ZG8 Aspire One AOD531H Aspire One AOD531H-Db Aspire One AOD531-0B Aspire One AOD531-0Bk Aspire One AOD531-15b Aspire One AOD531H-1766

Replaces Part Numbers

UM09A41 UM09B7C UM09B31 UM09B34 UM09B7D UM09A31 UM09A71 UM09A73 UM09A75 UM09B71 UM09B73

Technical Specifications

Voltage11.1V
Amp Hours6600mAh
Capacity6600mAh
Rate73.26Wh
Net Weight458g /16.16 oz
Gross Weight638g /22.50 oz
Approximate Weight638g /22.50 oz
Dimension 203.09 x 50.73 x 47.00mm

Product Highlights

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

Frequently Asked Questions

The Aspire One BIOS is showing the new battery as "0% available (plugged in, not charging)" — what's wrong?

The BIOS has not yet completed a learn cycle against the new cell's EEPROM data, so it cannot confirm charge state and holds the charger off as a safety measure. Shut the laptop down fully, disconnect AC, leave it for two minutes, then reconnect AC before powering on. If the charge still does not start, hold the power button for 15 seconds with AC disconnected to clear the EC latch, then reconnect and boot — charging should resume at that point.

Why does the Aspire One fuel gauge swing wildly — jumping from 60% to 15% in minutes on a new battery?

The fuel gauge IC calibrates itself against charge and discharge curves from the previous cell. A new 6600mAh cell has a different voltage-to-capacity slope, and the IC needs two to three full cycles before its internal model matches reality. Each wild reading is the IC correcting itself against fresh data. Run two complete discharge-to-hibernate and full charge-to-100% cycles without interrupting the charge, and the gauge readings will stabilise.

The replacement battery shows 73Wh in Windows but system info still displays the old lower Wh figure — is the cell faulty?

The Wh figure displayed in Windows Device Manager or battery reports is often pulled from the EEPROM of the old cell, cached in the OS power subsystem, not read live from the new cell. This is a data persistence issue, not a cell fault. Open Device Manager, uninstall the Microsoft ACPI-Compliant Control Method Battery entry, then reboot with AC connected — Windows will re-enumerate the battery and read the correct 73.26Wh from the new cell's EEPROM on the fresh install.

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Acer Aspire One 531 Replacement Battery, 11.1V, 6600mAh, Li-ion 1

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