Jetta JetBook 8500S Replacement Battery 11.1V 4400mAh

Jetta JetBook 8500S / 9700P / C250 Series — 11.1V Li-ion Replacement Battery

This is an 11.1V Li-ion battery rated at 4400mAh (48.84Wh) for the Jetta JetBook 8500S, 9700P, 9700S, C250P, and C250S notebooks. It replaces the factory cell when the original no longer holds a usable charge. Voltage and connector match the OEM spec across all five listed models.

• JetBook 8500S / 9700 / C250 platform fitment: These five models share the same 11.1V three-cell Li-ion architecture, identical connector pinout, and the same BMS communication protocol — so one cell replaces all. Swapping between the sub-variants does not require any hardware adaptation.
• Bench tested on actual hardware: We cycled this cell through charge and controlled discharge on the JetBook platform. The BMS handshake completed without fault codes, charge current tapered correctly in the CV phase, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
• Post-install calibration on the JetBook: After fitting this cell, 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 every cell swap on this platform.

BIOS reporting poor battery health immediately after fitting this cell

The JetBook BIOS reads health data from EEPROM registers carried over from the old cell during boot. A new cell has no matching charge history in those registers, so the firmware flags it as degraded before a single cycle completes. This is not a fault with the replacement cell. Run the full discharge-to-hibernate then uninterrupted charge sequence described above — the BIOS rewrites its health baseline after one complete learn cycle and the warning clears.

Laptop shutting down at 20–30% shown on the fuel gauge

The fuel gauge IC on the JetBook calibrates against the voltage curve of the original cell. With a new cell installed, the IC misreads the voltage-to-capacity relationship and triggers a shutdown well before the cell is actually empty. This is a gauge calibration issue, not a weak cell. Run two to three full discharge-and-charge cycles — the IC relearns the curve and the reported cutoff point drops back toward the correct 5–8% range. After calibration, confirmed terminal voltage at shutdown should sit around 9.9–10.2V under load.