BenQ JoyBook S52 Replacement Battery SQU-409 10.8V 4400mAh
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BenQ JoyBook S52 Replacement Battery SQU-409 10.8V 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.
BenQ JoyBook S52 Replacement Battery SQU-409 10.8V 4400mAh - is backordered and will ship as soon as it is back in stock.
Voltage
10.8V
Amp
4400mAh
BenQ JoyBook S52 Series — 10.8V Li-ion Replacement Battery (SQU-409)
This 10.8V, 4400mAh Li-ion battery replaces the original SQU-409 cell in the BenQ JoyBook S52, S52E, S52W, and S53 notebooks. It restores untethered operation on this mid-2000s ultraportable when the factory cell no longer holds a usable charge. Voltage and connector match the original spec exactly.
- JoyBook S52 series fit: The S52, S52E, S52W, and S53 all share the same battery bay geometry, 10.8V rail, and connector pinout. The BMS handshake protocol is identical across the series, so one cell fits all four variants without modification.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a JoyBook S52 chassis. The BMS accepted the cell on first contact, charge termination triggered correctly at 12.6V, and the protection circuit responded normally to load spikes during CPU-intensive tasks.
- Post-install calibration on the JoyBook S52: After installing, run one 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 swapping cells on this platform.
Why the JoyBook S52 BIOS reports poor battery health after a cell swap
The JoyBook S52 BIOS reads health data stored in the battery's EEPROM from the previous charge cycles. When a new cell arrives, that EEPROM counter reflects fresh or reset data that conflicts with what the BIOS expects for a "normal" battery. The system flags this mismatch as degraded health rather than a new cell. Running a full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the BIOS to rewrite its learned parameters against the new cell's actual chemistry.
JoyBook S52 shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC's capacity map no longer matches the new cell's real discharge curve. Under combined CPU and display load, the cell voltage drops faster than the old map predicts, hitting the BMS low-voltage cutoff while the OS still shows charge remaining. The fix is calibration: drain the battery fully until the laptop hibernates on its own, then charge to 100% without interruption — repeat this twice. After two full cycles the fuel gauge IC recalibrates and the shutdown-at-20% behaviour stops.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: BenQ
- 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 BenQ JoyBook S52 BIOS is showing the new battery as "Unknown" or 0% — is the cell dead?
No — the BIOS is reading stale EEPROM data that doesn't match the new cell yet. Boot into Windows, let the battery drain fully until the laptop hibernates on its own, then charge uninterrupted to 100%. That single learn cycle rewrites the BIOS health data against the new cell and clears the Unknown status.
My JoyBook S52 fuel gauge is jumping around wildly after swapping the battery — it shows 60%, then 80%, then back to 40% within minutes. What's happening?
The fuel gauge IC is still using the old cell's discharge curve to estimate charge. It needs two to three full calibration cycles before the readings stabilise. Drain to hibernate-cutoff, charge to 100%, repeat twice — after that the gauge tracks the new cell accurately and the erratic readings stop.
The replacement battery shows the wrong Wh rating in Windows system info compared to the original — should it match exactly?
Not necessarily. The Wh figure Windows reports pulls from the EEPROM's rated design capacity, which can differ slightly from the actual chemistry of the replacement cell. The functional capacity is 47.52Wh as tested. If the discrepancy concerns you, run a full discharge-to-hibernate cycle and check the "full charge capacity" reading in Windows Battery Report — that figure updates to reflect actual cell capacity after one complete cycle.
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