About this replacement
Toshiba Dynabook CX/45C Series — 10.8V Li-ion Replacement Battery (PA3593U-1BAS)
This is a 10.8V, 6600mAh Li-ion replacement battery for the Toshiba Dynabook CX series, including the CX/45C, CX/45D, CX/45E, CX/47C, and over 100 additional compatible models. It replaces OEM part numbers PA3593U-1BAS, PA3594U-1BRS, PABAS111, PA3593U-1BRS, and PA3595U-1BRS. Rated at 71.28Wh, it matches the original cell specification for voltage and capacity.
- Dynabook CX/45 and CX/47 platform fit: These models share the same battery bay geometry, 10.8V power rail, and connector pinout. The BMS handshake is consistent across the CX series, so the same cell works across all listed variants without modification.
- Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on the CX platform. The BMS communicated correctly with the host system, charge termination triggered at the expected voltage, and protection circuits responded normally under load.
- First-cycle reset on CX series: After fitting this battery, run the laptop down to hibernate-cutoff under normal use, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears in system utilities after a cell swap.
BIOS reporting poor battery health immediately after swapping the CX series cell
The Dynabook CX BIOS reads health data stored in the battery's EEPROM, not real-time cell voltage. When a new cell arrives, the EEPROM data does not match the laptop's learned baseline from the previous battery, so the BIOS flags it as degraded. This is not a fault with the replacement cell. Running one full discharge-to-hibernate then an uninterrupted charge to 100% allows the BIOS to write a new baseline. After that cycle, health reporting normalises.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's chemistry. The percentage shown on screen is still mapped to the old cell's discharge curve, so the laptop hits its low-voltage cutoff before the gauge reaches zero. The fix is two to three full discharge-and-charge cycles without interruption. After calibration, the gauge tracks correctly and the laptop will reach the expected cutoff at or below 5%.