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Toshiba Dynabook Qosmio 10.8V Replacement Battery PA3729U-1BAS

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From $76.99 USD $94.99
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Fits Toshiba Dynabook Qosmio GXW/70LW and replaces OEM part PA3729U-1BAS, PA3729U-1BRS, PA3730U-1BAS, PA3730U-1BRS.
10.8V 4400mAh lithium-ion cell delivers 47.52Wh — sufficient to sustain full CPU and display load on this mobile workstation without voltage sag.
Connector slides straight into the battery slot with no locking tab — orientation is keyed, and the pack sits flush against the chassis wall.
We bench-tested against a Dynabook Qosmio 97L motherboard; BMS handshake completed on first insertion and fuel gauge IC accepted the new cell without reporting errors.
Run one full discharge cycle to system hibernate, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears false health warnings from EEPROM data left by the original pack.
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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

10.8V

Amp

4400mAh

Toshiba Dynabook Qosmio GXW/70LW — 10.8V Li-ion Replacement Battery (PA3729U-1BAS)

This is a 10.8V, 4400mAh (47.52Wh) Li-ion replacement battery for the Toshiba Dynabook Qosmio GXW/70LW and related Qosmio models. It slots directly into the battery bay and restores portable operation after the original cell has degraded. OEM part numbers PA3729U-1BAS, PA3729U-1BRS, PA3730U-1BAS, PA3730U-1BRS, and PABAS207 all cross-reference this cell.

  • Qosmio series compatibility: The GXW/70LW, Qosmio 90LW, 97K, and 97L share the same 10.8V battery rail, connector pinout, and BMS handshake protocol — which is why a single cell covers this entire lineup without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on Qosmio-series hardware. The BMS negotiated correctly with the system board, charge current stepped down at the expected voltage threshold, and the protection circuit tripped cleanly at low-cell cutoff.
  • Post-install calibration on the Qosmio: After fitting this battery, 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 after every cell swap on these Toshiba models.

Why the Qosmio shuts down at 20–30% charge shown

Under combined CPU and display load, the Qosmio draws enough current to create a sharp voltage sag in the battery pack. When the cell voltage drops below the BMS cutoff threshold — even briefly — the system treats it as a dead pack and shuts down immediately. The state-of-charge percentage shown on screen is calculated by the fuel gauge IC, not measured in real time against that sag. A new cell and one full calibration cycle resets the fuel gauge's discharge curve so the reported percentage tracks the actual voltage more accurately.

BIOS reporting new battery health as "poor" or "replace battery" immediately after install

The Toshiba BIOS reads health data stored in the battery's EEPROM — and on a new replacement cell, that EEPROM does not yet carry the charge history the BIOS expects to see. The warning is a data mismatch, not a faulty cell. Run the full discharge-to-hibernate then uninterrupted charge-to-100% cycle once, and the BIOS learn cycle will write fresh baseline data to the EEPROM. After one complete cycle, the health warning clears on most Qosmio models.

Compatible Models

Dynabook Qosmio GXW/70LW Qosmio 90LW Qosmio 97K Qosmio 97L Qosmio G65 Qosmio G65W Qosmio G60 Qosmio G60/97K Qosmio X500 Qosmio X500-03L Qosmio X500-04N Qosmio X500-058 Qosmio X500-067 Qosmio X500-06C Qosmio X500-10Q Qosmio X500-10T Qosmio X500-10V Qosmio X500-10W Qosmio X500-10X Qosmio X500-116 Qosmio X500-11D Qosmio X500-11M Qosmio X500-11Q Qosmio X500-122 Qosmio X500-125 Qosmio X500-128 Qosmio X500-12D Qosmio X500-12F Qosmio X500-12N Qosmio X500-134 Qosmio X500-13R Qosmio X500-140 Qosmio X500-148 Qosmio X500-149 Qosmio X500-14C Qosmio X500-14D Qosmio X500-14W Qosmio X500-167 Qosmio X500-Q840S Qosmio X500-Q895S Qosmio X500-Q900S Qosmio X500-Q930X Qosmio X500-S1801 Qosmio X500-S1811 Qosmio X500-S1812 Qosmio X500-S1812X Qosmio X505 Qosmio X505-Q8100X Qosmio X505-Q8102X Qosmio X505-Q8104X Qosmio X505-Q830 Qosmio X505-Q832 Qosmio X505-Q850 Qosmio X505-Q860 Qosmio X505-Q862 Qosmio X505-Q865 Qosmio X505-Q870 Qosmio X505-Q875 Qosmio X505-Q879 Qosmio X505-Q880 Qosmio X505-Q882 Qosmio X505-Q885 Qosmio X505-Q887 Qosmio X505-Q888 Qosmio X505-Q890 Qosmio X505-Q892 Qosmio X505-Q893 Qosmio X505-Q894 Qosmio X505-Q896 Qosmio X505-Q898 Satellite P500 Satellite P500-01C Satellite P500-01R Satellite P500-024 Satellite P500-025 Satellite P500-026 Satellite P500-12D Satellite P500-12F Satellite P500-14L Satellite P500-1CG Satellite P500-1DT Satellite P500-1DW Satellite P500-1DX Satellite P500-1DZ Satellite P500-1F8 Satellite P500-BT2G22 Satellite P500-BT2G23 Satellite P500-BT2N20 Satellite P500-BT2N23 Satellite P500-ST5801 Satellite P500-ST6821 Satellite P500D-ST5805 Satellite P505 Satellite P505-S8940 Satellite P505-S8941 Satellite P505-S8945 Satellite P505-S8946 Satellite P505-S8950 Satellite P505-ST5800 Satellite P505D-S8930 Satellite P505D-S8934 Satellite P505D-S8935 Qosmio GXW/70LW

Replaces Part Numbers

PA3729U-1BAS PA3729U-1BRS PA3730U-1BAS PA3730U-1BRS PA3730 PABAS207

Technical Specifications

Voltage10.8V
Amp Hours4400mAh
Capacity4400mAh
Rate47.52Wh
Net Weight363g /12.80 oz
Gross Weight513g /18.10 oz
Approximate Weight513g /18.10 oz
Dimension 207.40 x 95.60 x 20.50mm

Product Highlights

  • Brand: Toshiba
  • 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 Qosmio fuel gauge is jumping around wildly — showing 60%, then 45%, then 70% within minutes of each other. Is the new battery faulty?

The fuel gauge IC calibrates itself against actual charge and discharge data from the cell it is paired with. A brand-new replacement cell has no history in the IC, so the percentage estimate is unreliable for the first few cycles. Run two to three full discharge-to-hibernate and uninterrupted charge-to-100% cycles. After that, the IC has enough real data to track the cell accurately and the readings stabilise.

The replacement battery shows the wrong Wh rating in Toshiba Power Saver — it says something lower than the 47.52Wh printed on the cell label.

The Wh figure shown in software is read from the battery EEPROM, which stores the rated capacity of the original chemistry at the time the cell was manufactured. The actual electrochemical capacity of the replacement cell may differ slightly from that stored value. This is an EEPROM data difference, not a physical capacity fault. Run a full calibration cycle — discharge to hibernate, then charge uninterrupted to 100% — and the system will update its calculated Wh figure to reflect the new cell.

The Qosmio won't charge above 80% after fitting the new battery — it just stops and holds there.

Some Toshiba BIOS versions include a charge limit setting that caps charging at 80% to reduce cell wear. Check Toshiba System Settings or the HWSetup utility under the Power tab for a "Battery Charge Mode" or "Eco Charge" option and switch it to full charge mode. If no such setting is present, the BIOS may be misreading the new cell's state due to a stale learn cycle — run a full discharge to hibernate cutoff, then charge uninterrupted, and the charge limit should release at 100%.

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