Toshiba Tecra Z40-A-17K Replacement Battery PA5149U-1BRS 14.4V
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Toshiba Tecra Z40-A-17K Replacement Battery PA5149U-1BRS 14.4V - 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
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Toshiba Tecra Z40-A-17K Replacement Battery PA5149U-1BRS 14.4V - is backordered and will ship as soon as it is back in stock.
Voltage
14.4V
Amp
3800mAh
Toshiba Tecra Z40/Z50-A Series — 14.4V Li-ion Replacement Battery (PA5149U-1BRS)
This is a 14.4V, 3800mAh (54.72Wh) Li-ion replacement battery for the Toshiba Tecra Z40-A-17K and the broader Tecra Z40/Z50-A and Z40-B series. It matches the OEM part number PA5149U-1BRS and uses the same connector and BMS handshake as the original cell. Voltage, capacity, and physical dimensions align directly with what the Z40-A-17K chassis expects.
- Tecra Z40/Z50-A and Z40-B compatibility: These models share the same 14.4V power rail, identical four-pin connector, and the same BMS communication protocol. The BIOS on all variants reads the battery via the same EEPROM query, so one cell covers the full platform without modification.
- Bench tested on actual hardware: We ran this cell on a Tecra Z40-A under full CPU and display load. The BMS held voltage above the 10.8V cutoff threshold throughout discharge, and charge acceptance reached 100% without triggering the BIOS charge-limit flag.
- BIOS learn cycle after install: After fitting this battery, run a single 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 any cell swap on this platform.
Why the Tecra Z40-A BIOS reports poor health immediately after a battery swap
The Z40-A BIOS reads charge cycle count, rated capacity, and health state directly from the battery's EEPROM at boot. A new cell carries fresh EEPROM data that doesn't match the learned values the BIOS stored from the old battery. Until a full discharge-to-hibernate and uninterrupted recharge cycle is completed, the BIOS treats the mismatch as a fault condition. After one full calibration cycle, the health status updates to normal and the warning clears.
Tecra Z40-A shutting down at 20–30% charge remaining
This happens when the cell cannot hold its voltage above the system cutoff threshold under combined CPU and display load — the fuel gauge shows percentage remaining, but voltage collapses faster than the gauge predicts. It is almost always a fuel gauge IC calibration issue on cycles 1–3 with a new cell, not a faulty battery. The gauge IC needs to observe a full discharge curve to map the new cell's voltage-to-capacity profile accurately. Run the Z40-A fully down to automatic hibernate at least twice, charging to 100% each time, and the shutdowns will stop.
Compatible Models
Replaces Part Numbers
Technical Specifications
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 Tecra Z40-A-17K says the battery is "unknown" in Toshiba Power Saver — new cell, just installed
The BIOS hasn't completed its EEPROM handshake with the new cell yet. Power Saver reads health and rated Wh from stored BIOS data, and a freshly installed cell hasn't written its values into that record. Run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. After that cycle, the BIOS rewrites the health record and Power Saver displays the correct status.
Windows shows this battery as 54Wh but Toshiba System Settings shows a different Wh figure — which is right?
Windows reads the Wh rating live from the battery's EEPROM, which reflects the actual rated chemistry of the cell — 54.72Wh. Toshiba System Settings can display a cached figure pulled from the BIOS learn record, which still holds the old cell's rated value until the learn cycle is reset. The 54.72Wh figure from Windows Device Manager is correct. Complete one full discharge-to-hibernate and recharge cycle to force System Settings to update its cached value.
Fuel gauge on my Z40-A-17K is jumping around — shows 60%, then drops to 40% without warning after fitting this replacement
The fuel gauge IC on the Z40-A calibrates against the discharge curve of the installed cell. A new cell with a different internal resistance profile causes the IC to misread state-of-charge until it has mapped a full discharge cycle. This is expected behaviour for cycles 1–3. Let the laptop discharge fully to automatic hibernate twice, charging to 100% each time, and the gauge will stabilise to within a few percentage points of actual capacity.
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