Terrans Force X511-6990-8 Replacement Battery 14.8V 5200mAh

Terrans Force X511-6990-8 Series — 14.8V Li-ion Replacement Battery

This is a 14.8V, 5200mAh (76.96Wh) Li-ion replacement battery for the Terrans Force X511-6990-8 and compatible notebook models. It fits a broad range of Terrans Force laptops sharing the same voltage rail and connector layout, including the X711-1080-67SH1, X511-6970-7, and X511-580-8. Install it when the original cell no longer holds a usable charge.

• X511 and X711 series compatibility: These models share the same 14.8V four-cell architecture, identical connector pinout, and BMS handshake protocol — which is why a single cell covers the full range without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a Terrans Force notebook and confirmed the BMS handshake completes correctly, charge acceptance reaches rated capacity, and no false fault codes are thrown during the process.
• Post-install discharge cycle: After fitting this battery, run the laptop on battery alone until it hibernates at cutoff, then charge uninterrupted to 100%. This forces the BIOS to complete a learn cycle against the new cell and clears the inaccurate battery health warning that appears after any cell swap.

BIOS reporting poor battery health immediately after fitting a new cell

The Terrans Force BIOS reads health data stored in the battery's EEPROM, not live cell voltage. When you swap cells, the EEPROM data no longer matches the new chemistry, so the BIOS flags it as degraded. This is not a fault with the replacement — it is a stale data mismatch. Run one full discharge-to-hibernate cycle followed by a complete uninterrupted charge. After two to three cycles the BIOS recalibrates its stored values and the health warning clears.

Laptop shutting down abruptly at 20–30% charge shown on screen

This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve. The gauge is still mapping charge percentage to the old cell's discharge profile, so it misreads the voltage cliff and triggers shutdown early. The fix is two to three full discharge cycles — let the laptop run on battery until it hibernates each time, then charge fully without interruption. After those cycles the fuel gauge IC realigns its percentage readings to the new cell and the premature shutdowns stop.