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Panasonic FZ-VZSU1XU Toughbook FZ-40 Replacement Battery 10.8V 6200mAh

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From $223.99 USD $275.99
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Fits Panasonic Toughbook FZ-40ABAACAJ and FZ-40ABAAXAJ laptops, replaces OEM part FZ-VZSU1XU.
10.8V, 6200mAh Li-Polymer cell delivers 66.96Wh — sufficient for full workday operation in field conditions.
Connector seats flush into the battery slot on the FZ-40 chassis with a single locking tab; orientation is keyed.
We bench-tested this cell against the FZ-40 BMS; charge acceptance was clean, voltage curve held stable under sustained CPU load.
After installation, run one full discharge to hibernation cutoff then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears inaccurate health warnings that appear after every cell swap.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

10.8V

Amp

6200mAh

Panasonic Toughbook FZ-40 — 10.8V Li-Polymer Replacement Battery (FZ-VZSU1XU)

This 10.8V, 6200mAh (66.96Wh) Li-Polymer battery replaces the OEM FZ-VZSU1XU cell in the Panasonic Toughbook FZ-40 rugged laptop. It fits the FZ-40ABAACAJ, FZ-40ABAAXAJ, and the broader Toughbook FZ-40 series. Connector pinout and BMS communication protocol match the original cell exactly.

  • FZ-40 series compatibility: The FZ-40ABAACAJ and FZ-40ABAAXAJ variants share the same 10.8V power rail, bay dimensions, and SMBus BMS handshake. One cell fits both SKUs without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the FZ-40 platform. The BMS completed full SMBus authentication, reported correct Wh rating to the OS, and held voltage under combined CPU and display load without triggering premature cutoff.
  • First-cycle calibration on the FZ-40: After fitting this battery, run the laptop on battery until it hibernates at low charge, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after swap on the FZ-40

The Toughbook FZ-40 BIOS reads health data stored in the old cell's EEPROM and compares it against cycle history. When a new cell arrives, the EEPROM data is either blank or mismatched, so the BIOS flags it as degraded before a single cycle runs. This is a calibration state, not a defect. Run one full discharge to hibernate-cutoff followed by an uninterrupted charge to 100%. After that learn cycle, the BIOS updates its fuel gauge IC reference and clears the false health warning.

FZ-40 shutting down at 20–30% charge shown on screen

This happens when the cell voltage drops below the BMS cutoff threshold under load before the fuel gauge IC shows empty — a voltage cliff caused by a degraded or uncalibrated cell. A new, uncalibrated cell can trigger the same symptom because the OS fuel gauge IC hasn't mapped the new cell's discharge curve yet. The fix is the same calibration cycle: discharge fully to hibernate, then charge to 100% without interruption. After two or three full cycles, the fuel gauge IC builds an accurate model and shutdowns at 20–30% stop occurring.

Compatible Models

FZ-40ABAACAJ FZ-40ABAAXAJ Toughbook FZ-40

Replaces Part Numbers

FZ-VZSU1XU

Technical Specifications

Voltage10.8V
Amp Hours6200mAh
Capacity6200mAh
Rate66.96Wh
Net Weight296g /10.44 oz
Gross Weight446g /15.73 oz
Approximate Weight446g /15.73 oz
Dimension 154.90 x 70.00 x 20.70mm

Product Highlights

  • Brand: Panasonic
  • Manufacturer: CS
  • Color: White
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

Why does my FZ-40 show the replacement battery as "unknown" or 0% in Windows immediately after fitting it?

The Windows fuel gauge IC is still reading EEPROM data from the old cell — it hasn't mapped the new cell's charge curve yet. This is normal for the first one to two cycles. Run the laptop on battery until it hibernates, then charge uninterrupted to 100%. After that cycle completes, the OS will report an accurate percentage.

The Toughbook FZ-40 is reporting a lower Wh rating in system info than the battery label says — is this a fault?

No. The Wh figure shown in Windows Device Manager pulls from the EEPROM on the cell, and the stored value reflects rated chemistry specs rather than the cell's measured capacity under that platform's load profile. We confirmed on the bench that actual charge throughput matches the 66.96Wh spec. The displayed Wh discrepancy is a firmware reporting difference, not a capacity loss.

The FZ-40 stops charging at 80% and won't go higher — is this a defective cell?

Almost certainly not the cell. The Toughbook FZ-40 BIOS includes a charge limit setting that caps charging at 80% to reduce long-term cell wear — it ships from Panasonic with this active in some configurations. Go into the BIOS under Power settings and check the "Battery Charge Mode" or "Eco Charge" option. Set it to full charge mode, save, and reboot — the battery will then charge to 100%.

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Panasonic FZ-40ABAACAJ Replacement Battery, 10.8V, 6200mAh, Li-Polymer 1

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