Casio Cassiopeia BE-300 Replacement Battery CGA-1-105A 3.7V 800mAh

Casio Cassiopeia BE-300 / BE-500 — 3.7V Li-ion Replacement Battery (CGA-1-105A)

This is a 3.7V, 800mAh Li-ion replacement for the Casio Cassiopeia BE-300 and BE-500 pocket PC. Both handhelds share the same battery bay, connector, and BMS communication protocol. Capacity figures come from the product data — 800mAh / 2.96Wh.

• BE-300 and BE-500 compatibility: Both models use the same physical form factor, 3.7V nominal rail, and CGA-1-105A part number. The connector pinout and BMS handshake are identical across both units, so one cell covers both devices without any modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the BE-300 platform. The BMS accepted the charge curve without fault flags, and the protection circuit tripped correctly at the low-voltage threshold before cell damage could occur.
• RAM data preservation before swap: Sync all open files and application state to your host PC before removing the battery. The BE-300 and BE-500 hold active data in volatile SRAM powered directly by the main cell — a full power interruption clears that memory instantly, with no recovery path.

Why the Cassiopeia BE-300 loses all data on a battery swap

The BE-300 uses SRAM for active storage — unlike flash memory, SRAM requires continuous power to hold its contents. When the main battery is removed and no backup cell is present, voltage drops to zero and the entire RAM contents are erased. This is not a fault in the new battery; it is a hardware characteristic of the platform. Sync to ActiveSync or a desktop backup before any battery removal to prevent data loss.

Cassiopeia BE-300 stuck on boot screen after new battery installed

A freshly shipped Li-ion cell may arrive at 30–50% state of charge — sometimes below the minimum voltage the BE-300 boot sequence requires to complete POST. If the device stalls on the startup screen or cycles without loading the OS, connect it to the charger for at least 30 minutes before attempting to boot again. The BMS will not allow the device to draw full boot current until the cell voltage clears approximately 3.5V. Charge first, then power on.