Fujitsu SQU-805 LifeBook SW8 Replacement Battery 11.1V 4400mAh
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Fujitsu SQU-805 LifeBook SW8 Replacement Battery 11.1V 4400mAh - 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
⚠️ 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.
Fujitsu SQU-805 LifeBook SW8 Replacement Battery 11.1V 4400mAh - is backordered and will ship as soon as it is back in stock.
Voltage
11.1V
Amp
4400mAh
Fujitsu SW8 / TW8 — 11.1V Li-ion Replacement Battery (SQU-805)
This 11.1V, 4400mAh Li-ion battery replaces the original cell in the Fujitsu LifeBook SW8 and TW8 notebooks. It cross-references OEM part numbers SQU-804, SQU-805, SQU-807, SW8-3S4400-B1B1, and several others listed above. Slot it in and the laptop runs on battery power as it did from day one.
- SW8 and TW8 shared battery platform: Both models use the same 3-cell 11.1V architecture, identical connector pinout, and the same BMS handshake protocol — which is why a single part number covers both. Swapping between a SW8 and TW8 unit produces no recognition errors at the firmware level.
- Bench tested on actual hardware: We ran this cell on a SW8 unit and monitored the BMS through full charge and a load discharge cycle. The protection circuit responded correctly to over-charge, over-discharge, and short-circuit triggers. The BIOS detected the battery without driver prompts.
- First-cycle calibration on the SW8: After installing, run one full discharge to the hibernate cut-off point, then charge uninterrupted to 100%. This single learn cycle resets the BIOS battery counter against the new cell and clears the inaccurate health warning that appears after every cell swap on this platform.
BIOS reporting poor battery health immediately after fitting a new cell
The SW8 BIOS stores charge history and wear data in EEPROM tied to the old cell. When a new battery is installed, that stored data does not match the fresh cell's actual state, so the system flags the battery as degraded. This is a data mismatch, not a fault with the replacement. Running one complete discharge-to-hibernate followed by a full uninterrupted charge resets the learn cycle. After that single cycle, the BIOS health reading aligns with the new cell's actual capacity.
LifeBook SW8 shutting down abruptly at 20–30% charge shown
This is a voltage cliff symptom. When the combined CPU and display load draws peak current, a weakened or uncalibrated cell drops below the BMS cutoff voltage before the fuel gauge IC reaches zero — the system cuts power with charge still displayed on screen. On a new replacement cell, this usually means the fuel gauge IC has not yet calibrated against the new chemistry. Complete two full discharge-to-hibernate and charge-to-100% cycles. If the shutdowns continue past three cycles, check the BIOS battery page for a reported voltage below 10.8V under load.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Fujitsu
- 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
The SW8 shows the replacement battery as "0% available (plugged in, charging)" and never moves off zero — what's wrong?
The fuel gauge IC is reading EEPROM data from the old cell and has lost its reference point for the new one. Disconnect the AC adapter, let the laptop run on battery until it hibernates, then charge uninterrupted to 100% without interruption. That one full cycle gives the IC a new baseline and the percentage reading corrects itself from the next boot.
My SW8 charge stopped at 80% and the charging light went off — is the battery faulty?
Most likely not. The Fujitsu LifeBook BIOS on this platform includes a battery charge limit setting that caps charging at 80% to reduce cell wear — it ships enabled on some units. Go into the BIOS (F2 at POST), find the Power Management or Battery section, and look for a charge limit or eco-charge setting. Disable it or set the threshold to 100%, then reboot and reconnect the charger.
System information shows this battery as 40Wh but the spec says 48.84Wh — which is correct?
The 48.84Wh figure on the label reflects the actual cell chemistry. The lower number in system info is pulled from the EEPROM on the old battery or from a cached firmware value that has not yet updated to the new cell's data. Run a full discharge-to-hibernate cycle followed by a complete charge to 100%, then check the Wh reading again in the BIOS battery status screen — it should update to reflect the correct 48.84Wh rating.
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