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Toshiba Dynabook BJ65/FS Replacement Battery 11.4V PA5344U-1BRS

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From $112.99 USD $139.99
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Fits Toshiba Dynabook BJ65/FS notebook; replaces OEM part PA5344U-1BRS battery pack.
Delivers 11.4V at 3750mAh (42.75Wh) — matches original capacity for full portable session duration.
Connector seats flush into the battery bay slot with positive latch; no adapter needed.
Bench testing showed clean BMS voltage ramp on first charge with stable cell balancing throughout discharge cycle.
After installation, discharge fully to system shutdown then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears false health warnings that appear after 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.

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⚠️ 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

11.4V

Amp

3750mAh

Toshiba Dynabook BJ65/FS — 11.4V Li-Polymer Replacement Battery (PA5344U-1BRS)

This is an 11.4V, 3750mAh (42.75Wh) Li-Polymer battery for the Toshiba Dynabook BJ65/FS notebook. It replaces OEM part PA5344U-1BRS and restores portable operation when the original cell has degraded or failed. Dimensions are 190.50 × 102.80 × 7.00mm — verify clearance before ordering if the bay has been modified.

  • Dynabook BJ65/FS compatibility: The BJ65/FS uses a three-cell Li-Polymer pack on an 11.4V rail with a proprietary SMBus connector. This battery matches that rail voltage, physical footprint, and connector pinout so the BMS handshake completes on first boot.
  • Bench tested on actual hardware: We ran this cell through charge, full-load discharge, and BMS communication checks. The BMS flagged no fault codes, cell balancing held within spec across all three cells, and the pack reported correct Wh data to the host system.
  • Post-install calibration on the BJ65/FS: After fitting, run one full discharge to hibernate-cutoff — do not interrupt it — then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning the firmware shows after any cell swap on this model.

Why the BJ65/FS BIOS reports poor battery health immediately after a cell swap

The BJ65/FS stores learned battery data — cycle count, capacity history, and health flags — in EEPROM on the old pack. When a new cell goes in, the BIOS reads that register as empty or mismatched and flags the battery as degraded. This is not a fault with the replacement cell. Running the full discharge-to-hibernate then uninterrupted charge sequence gives the BIOS enough data to rewrite the health register. After one or two complete cycles, the health indicator returns to normal.

BJ65/FS shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC is still calibrated to the old cell's voltage curve. The gauge reads 25% but the actual cell voltage has already dropped below the BMS cutoff threshold under combined CPU and display load. The laptop cuts power before the screen shows zero. Fix it by completing two full discharge-to-hibernate cycles without interruption — this forces the fuel gauge IC to map the new cell's actual voltage cliff. After the second cycle, the shutdown point and displayed percentage will align, typically at or below 5%.

Compatible Models

Dynabook BJ65/FS

Replaces Part Numbers

PA5344U-1BRS

Technical Specifications

Voltage11.4V
Amp Hours3750mAh
Capacity3750mAh
Rate42.75Wh
Net Weight206g /7.27 oz
Gross Weight346g /12.20 oz
Approximate Weight346g /12.20 oz
Dimension 190.50 x 102.80 x 7.00mm

Product Highlights

  • Brand: Toshiba
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The Dynabook BJ65/FS shows the replacement battery as "0% available (plugged in, not charging)" — what's wrong?

This usually means the BMS handshake did not complete on first boot. Shut the laptop down fully, remove the AC adapter, hold the power button for 15 seconds to drain residual charge from the board, then reconnect AC and boot. If the system still shows 0%, enter the BIOS, let it sit on the battery info screen for 60 seconds, then exit and reboot — this forces an SMBus re-poll and clears the stale EEPROM data from the previous cell.

The BJ65/FS fuel gauge is jumping around — shows 60%, then 45%, then 70% within minutes. Is the new battery faulty?

It is not faulty. The fuel gauge IC on this model calibrates itself against cycle history stored on the old pack. With a new cell, that history is blank, so the gauge interpolates badly for the first few cycles. Run two complete discharges to hibernate-cutoff followed by uninterrupted charges to 100%. After the second cycle the IC has enough data points to track the new cell's voltage curve accurately and the jumping stops.

Why does Windows report this battery as 38Wh when the spec is 42.75Wh?

Windows reads the Wh figure from the EEPROM design-capacity register, which reflects the rated value written at manufacture. Li-Polymer cells ship at a slightly lower measured capacity than their rated value, and the BMS applies a small margin on top. The 3–5Wh difference between reported and rated Wh is normal for this chemistry and does not indicate a faulty or underspec cell. If the reported value drops significantly further after calibration cycles — below 35Wh — that would point to a genuine cell issue worth investigating.

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Toshiba Dynabook BJ65/FS Replacement Battery, 11.4V, 3750mAh, Li-Polymer 1

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