Toshiba Chromebook CB30-100 Replacement Battery PA5171U-1BRS 14.8V

Toshiba Chromebook CB30-100 Series — 14.8V Li-Polymer Replacement Battery (PA5171U-1BRS)

This is a 14.8V, 3300mAh (48.84Wh) Li-Polymer battery for the Toshiba Chromebook CB30-100, CB30-102, and CB30-A3120 series. It replaces OEM part PA5171U-1BRS directly. If your CB30 no longer holds a charge or fails to power on away from the wall, this cell restores full portable operation.

• CB30-100 / CB30-102 / CB30-A3120 compatibility: These models share the same battery bay dimensions, 14.8V voltage rail, and PA5171U-1BRS connector pinout. The BMS handshake protocol is identical across the series, so one cell covers all three variants without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the CB30 platform. The BMS communicated correctly with the Chromebook's charge controller, and the fuel gauge IC tracked state-of-charge without dropout throughout the test.
• First-cycle reset procedure for CB30: After fitting the new cell, let the Chromebook discharge fully until it hibernates, then charge uninterrupted to 100% without powering the device on mid-charge. This forces the BIOS battery learn cycle to reset against the new cell's actual capacity and clears the false health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after fitting a new CB30 cell

The CB30's BIOS reads health data from EEPROM registers written by the original cell during its service life. A new cell ships with factory EEPROM values that do not match what the BIOS expects, triggering a false "poor health" or "replace battery" flag right after installation. This is not a fault with the replacement cell — it is a calibration mismatch. Running one full discharge-to-hibernate cycle followed by a continuous charge to 100% rewrites the learn cycle data and clears the warning. After two to three full cycles, BIOS-reported health will stabilise.

CB30 shutting down at 20–30% charge shown on the OS gauge

This happens when the aged original cell can no longer sustain voltage under combined CPU and display load — the actual cell voltage drops below the BMS cutoff threshold before the fuel gauge reaches 0%. The OS gauge is reading a stale capacity map, not real-time cell voltage. Fitting a new cell eliminates the voltage cliff, but the fuel gauge IC still needs calibration cycles to map the new cell accurately. Run two full discharge-to-hibernate and recharge cycles; the gauge should track to within a few percent of actual remaining capacity by the third cycle.