Toshiba Portege 3500 Replacement Battery PA3228 10.8V 3600mAh

Toshiba Portege 3500 / 3505 — 10.8V Li-ion Replacement Battery (PA3228)

This is a 10.8V, 3600mAh Li-ion battery for the Toshiba Portege 3500 and Portege 3505 laptops. It replaces OEM part numbers PA3228, PA3228U-1BAS, and PA3228U-1BRS. If your original pack no longer holds a usable charge, this cell slots into the same bay and connects to the same BMS interface.

• Portege 3500 and 3505 compatibility: Both models run the same 10.8V three-cell architecture and share the PA3228 connector and BMS handshake protocol. One replacement covers both.
• Bench tested on actual hardware: We cycled this cell on a Portege 3500 unit — the BMS accepted the new pack without fault codes, charge current ramped correctly through CC/CV, and the fuel gauge IC tracked the discharge curve without dropout.
• First-cycle calibration on the Portege 3500: After fitting, 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 battery health as poor after replacement on the Portege 3500

The Portege 3500 BIOS reads health data from EEPROM stored on the battery pack, not from live cell measurements. When a new cell ships, that EEPROM data does not match the BIOS's learned history from the old pack, so it flags the battery as degraded even though the cell is fresh. Running a full discharge-to-hibernate followed by an uninterrupted charge to 100% lets the BIOS rewrite its learn cycle against the new cell's actual capacity curve. After one or two full cycles, the health indicator normalises.

Portege 3500 shutting down at 20–30% charge shown on the gauge

This happens when the fuel gauge IC hasn't yet calibrated against the new cell's voltage curve — it misreads the remaining capacity and signals shutdown before the cell is actually empty. The underlying cause is a mismatch between the IC's stored discharge model and the new cell's actual voltage-vs-charge relationship. Fix it by running two full discharge-to-hibernate cycles followed by full uninterrupted charges. After the second cycle, the fuel gauge reanchors its cutoff threshold and the premature shutdown stops. Check that the BIOS shutdown voltage is set no lower than 10.5V across the three-cell stack.