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Toshiba Dynabook Qosmio 10.8V Replacement Battery PA3729U-1BAS

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From $97.99 USD $120.99
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Fits Toshiba Dynabook Qosmio GXW/70LW and replaces OEM part number PA3729U-1BAS.
10.8V, 8800mAh capacity delivers full charge cycles to this Dynabook without voltage sag midway through a session.
Connector slides straight into the battery bay with a single locking tab; no force needed on insertion.
We bench-tested this cell on the GXW/70LW platform—BMS accepted the new pack and charged to 100% without firmware lockout.
After installation, run one full discharge cycle to hibernation-cutoff then charge uninterrupted to reset the BIOS battery learn cycle.
Extended delivery time

Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.

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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

8800mAh

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

This is a 10.8V, 8800mAh (95.04Wh) Li-ion replacement battery for the Toshiba Dynabook Qosmio GXW/70LW and related Qosmio notebook models. It replaces OEM part numbers PA3729U-1BAS, PA3729U-1BRS, PA3730U-1BAS, PA3730U-1BRS, and PABAS207. The Qosmio line draws significant power from its display and GPU subsystem, so cell capacity here matters more than on lighter notebooks.

  • Qosmio GXW, 90LW, 97K, 97L series compatibility: These models share the same battery bay geometry, connector pinout, and BMS handshake protocol. The PA3729/PA3730 part numbers are interchangeable across this platform because Toshiba used the same charging circuit and communication lines throughout the Qosmio generation.
  • Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on Qosmio-platform hardware. The BMS communicated correctly with the system controller, charge termination triggered at 100%, and the protection circuit responded normally to load spikes from the GPU and display backlight.
  • Post-install discharge cycle on Qosmio: After fitting this battery, run the notebook on battery power until it hibernates at the low-charge cutoff, then charge uninterrupted to 100%. The Qosmio BIOS uses a battery learn cycle to calibrate its fuel gauge IC — skipping this step leaves the system reporting inaccurate health warnings and erratic charge percentages.

Why the Qosmio BIOS flags a new battery as poor health immediately after install

The Qosmio firmware reads EEPROM data stored on the battery's BMS chip. A new cell ships with factory EEPROM values that do not match the learned cycle history the BIOS expects from the original unit. Until the learn cycle runs, the system reports "poor health" or a low Wh figure — not because the cell is faulty, but because the BIOS has not yet calibrated against the new cell's actual charge curve. One full discharge-to-hibernate then full charge clears this. After two to three cycles, the reported health figure stabilises.

Qosmio shutting down at 20–30% charge shown on screen

This happens when the cell voltage drops below the system's minimum threshold under full CPU and display load, even though the fuel gauge still shows charge remaining. The original calibration data no longer matches the new cell, so the OS gauge and the actual cell voltage diverge. Under sustained load — particularly when the GPU and backlight are both running — voltage sags faster than the gauge expects, triggering an immediate shutdown. Discharge fully to hibernate cutoff, charge to 100% uninterrupted, and repeat once more — after two calibration cycles the shutdown threshold and displayed percentage will align.

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 Hours8800mAh
Capacity8800mAh
Rate95.04Wh
Net Weight593.5g /20.94 oz
Gross Weight743.5g /26.23 oz
Approximate Weight743.5g /26.23 oz
Dimension 207.40 x 95.60 x 23.20mm

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

The BIOS fuel gauge IC is reading stale EEPROM data from the old cell and has not yet mapped its charge curve to the new one. This is a calibration issue, not a faulty battery. Run the notebook on battery only until it hibernates, then charge uninterrupted to 100% without using the machine. After one full cycle the gauge will begin tracking correctly, and after two cycles the 0% reading clears entirely.

The Qosmio system info screen reports this battery at 65Wh when the cell is rated 95.04Wh — is the battery wrong?

No — the reported Wh figure in Toshiba's system information reads from the EEPROM on the battery's BMS chip, which ships with factory default values, not the calibrated figure the old cell had written over time. The actual cell chemistry and rated capacity are correct at 95.04Wh. Run two full discharge-to-hibernate and full-charge cycles and the reported Wh value will update to reflect the real cell capacity as the BMS writes new data to EEPROM.

Charge stops at exactly 80% and the Qosmio won't charge beyond that point — is the battery defective?

This is almost always the Toshiba BIOS charge limit setting, not a cell fault. Some Qosmio firmware versions ship with or default to an 80% charge ceiling under the "Eco Charge" or battery care mode — it is controlled entirely by the BIOS, not the battery. Go into Toshiba System Settings (or the Toshiba Settings app), locate the battery charge mode option, and switch it from "Eco" to "Full Charge." The battery will then charge to 100%.

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