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Fujitsu Lifebook U77 FPCBP372 Replacement Battery 14.4V 3100mAh

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From $97.99 USD $120.99
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Fits Fujitsu Lifebook U77 models using OEM part numbers FPCBP372 or FMVNBP220.
14.4V lithium-polymer chemistry with 3100mAh capacity delivers 44.64Wh total energy for standard workday portability.
Connector seats straight into the U77 battery slot with single locking tab release on the housing.
We bench-tested against OEM charge profiles; the BMS settled into stable voltage at 100% within three full cycles.
After installation, discharge fully to system sleep, then charge uninterrupted to 100% — this runs the Lifebook's BIOS battery learn cycle and clears false low-health warnings the firmware flags after every cell swap.
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

14.4V

Amp

3100mAh

Fujitsu Lifebook U77 — 14.4V Li-Polymer Replacement Battery (FPCBP372)

This 14.4V, 3100mAh (44.64Wh) lithium-polymer cell replaces the OEM battery in the Fujitsu Lifebook U77 ultraportable notebook. It matches the original connector, dimensions, and BMS handshake the U77 motherboard expects. OEM part numbers FPCBP372 and FMVNBP220 both cross-reference this cell.

  • Lifebook U77 fitment: The U77 uses a thin Li-Polymer pack in a flat sled form factor — 258.00 x 100.40 x 6.90mm. The BMS communicates with the BIOS over SMBus, so the connector pinout and EEPROM data structure must match exactly. This cell carries the correct SMBus-compatible firmware the U77 BIOS interrogates at boot.
  • Bench tested on actual hardware: We cycled this cell through charge, idle, and load on U77-compatible hardware. The BMS reported state-of-charge correctly, charge termination triggered at the expected voltage, and no fault codes appeared during the SMBus handshake.
  • First-cycle calibration on the U77: After fitting, run the laptop on battery until it hibernates at the low-voltage cutoff, then charge uninterrupted to 100% without interruption. This completes the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.

BIOS reporting battery health as poor after fitting a new cell in the U77

The U77 BIOS reads health data stored in the battery's EEPROM — not the actual cell chemistry. When a new cell arrives, that EEPROM data doesn't match the learned baseline the BIOS built against the old pack. The system flags it as degraded before any real wear has occurred. Running a full discharge-to-hibernate then a complete uninterrupted charge resets this baseline. After one or two full cycles the health indicator normalises.

Laptop shuts down at 20–30% charge shown on the U77 fuel gauge

This happens when the fuel gauge IC hasn't yet calibrated against the new cell's actual discharge curve. The IC maps voltage to percentage using data from the old cell — the voltage cliff comes earlier than the gauge expects, and the system cuts out. It is not a fault in the new cell. Run two to three full discharge and charge cycles without interruption, and the fuel gauge IC will recalibrate its voltage-to-capacity map. After calibration, shutdown should not occur above 5–8% reported charge.

Compatible Models

Lifebook U77

Replaces Part Numbers

FPCBP372 FMVNBP220

Technical Specifications

Voltage14.4V
Amp Hours3100mAh
Capacity3100mAh
Rate44.64Wh
Net Weight269.4g /9.50 oz
Gross Weight529.4g /18.67 oz
Approximate Weight529.4g /18.67 oz
Dimension 258.00 x 100.40 x 6.90mm

Product Highlights

  • Brand: Fujitsu
  • 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 U77 shows the battery as "unknown" or 0% immediately after fitting the new cell — is the EEPROM the problem?

Yes. The U77 BIOS reads identity and state data from the battery's EEPROM over SMBus. A new cell carries EEPROM values the BIOS hasn't seen before, so it reports unknown or 0% until it completes a learn cycle. Plug in AC power and let the battery charge fully to 100% without interruption, then discharge to hibernate cutoff once. After that first complete cycle the BIOS should read the battery normally.

The fuel gauge on the U77 jumps wildly between percentages for the first few uses — what causes that?

The fuel gauge IC calibrates its percentage readings against the discharge curve of the previous cell. A new cell has a slightly different voltage profile, so the IC's estimates are inaccurate until it maps the new curve. This is normal for the first two to three full cycles and is not a hardware fault. Run the battery from 100% down to hibernate cutoff twice without interrupting either cycle and the gauge will stabilise.

The U77 won't charge above 80% after fitting this battery — is there a fix?

This is almost always the BIOS charge-limit feature, not a fault with the cell. Fujitsu's Power Manager utility includes a setting that caps charge at 80% to reduce long-term cell stress. Open Fujitsu Power Manager, navigate to Battery Settings or Charging Mode, and set the charge limit to 100%. If Power Manager isn't installed, check BIOS under Power — some U77 firmware versions expose the charge ceiling there directly.

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