Casper TW8 Replacement Battery SQU-805 11.1V 4400mAh
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Casper TW8 Replacement Battery SQU-805 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.
Casper TW8 Replacement Battery SQU-805 11.1V 4400mAh - is backordered and will ship as soon as it is back in stock.
Voltage
11.1V
Amp
4400mAh
Casper TW8 — 11.1V Li-ion Replacement Battery (SQU-805)
This is an 11.1V 4400mAh Li-ion replacement battery for the Casper TW8 notebook. It replaces the original cell when capacity has degraded to the point where the laptop no longer holds a useful charge away from the wall. Fits models listed under OEM part numbers SQU-805, SQU-804, SQU-807, and SW8-3S4400-B1B1 among others.
- TW8 platform compatibility: The TW8 series uses a shared battery bay and connector across variants covered by the SQU-80x family. The BMS handshake voltage and connector pinout are consistent across these part numbers, which is why multiple OEM codes map to the same physical cell pack.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the TW8 platform. The BMS communicated correctly with the system board, charge acceptance was normal from the first cycle, and no overcurrent trips occurred under sustained CPU and display load.
- Post-install calibration on the TW8: After fitting this battery, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100% without interrupting it. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after most cell swaps on this platform.
BIOS reporting battery health as poor after fitting a new cell
The TW8 BIOS reads health data stored in the battery's EEPROM. When a new cell arrives, that EEPROM data does not yet match what the system expects from a calibrated pack. The BIOS interprets this mismatch as degraded health even though the cell is new. Running one full discharge-to-hibernate then a full uninterrupted charge cycle allows the firmware to rewrite its learned capacity baseline and clears the warning on next boot.
TW8 shutting down abruptly at 20–30% charge shown on screen
This happens when the cell voltage drops below what the system board will sustain under combined CPU and display load, even though the fuel gauge still reads above zero. The gauge IC is calibrated against the old cell's discharge curve, so it overestimates remaining charge at the voltage cliff. After two or three full calibration cycles, the fuel gauge IC recalibrates against the new cell's actual curve. Shutdowns should stop once the gauge tracks the new cell accurately — typically by the third full cycle.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Casper
- 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 Casper TW8 shows the new battery as "0% — consider replacing" in Windows immediately after fitting it. Is the cell faulty?
It is not faulty. The Windows fuel gauge IC is reading EEPROM data that does not yet match the new cell's chemistry profile, so it reports an invalid health state. Run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. By the second or third cycle the gauge recalibrates and the warning clears.
The TW8 battery indicator shows 48Wh in the BIOS spec screen, but Windows reports a different Wh figure in power settings — why don't they match?
The BIOS reads the Wh rating stored in the battery's EEPROM at manufacture, which reflects the rated cell specification. Windows calculates Wh dynamically from the fuel gauge IC's live voltage and current readings, which shift as the cell settles over early cycles. The two figures converge after two or three full calibration cycles once the fuel gauge has mapped the actual discharge curve of the new cell.
The Casper TW8 charge stops at 80% and will not go higher no matter how long it stays plugged in — is this a battery problem?
This is almost always a BIOS-controlled charge limit, not a cell fault. Many notebook BIOS versions ship with a battery care or conservation mode enabled that caps charging at 80% to reduce long-term wear. Check the Casper BIOS power settings or any installed battery management utility and disable the charge limit. Once turned off, the battery will charge to 100%.
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