About this replacement
Toshiba Satellite 5205-S505 Series — 10.8V Li-ion Replacement Battery (PA3216U-1BAS)
This is a 10.8V, 6600mAh Li-ion battery for the Toshiba Satellite 5200 and 5205 series laptops. It fits the Satellite 5205-S505, 5200-A750, 5200-801, and 5205-SP505, among 22 additional models in this line. OEM cross-references include PA3216U-1BRS, PA3288U-1BAS, PA3288U-1BRS, and PABAS025.
- Satellite 5200 and 5205 platform fit: These models share the same 10.8V power rail, three-pin connector layout, and BMS handshake protocol — the BIOS authenticates the cell over the SMBus line before allowing charge. Any cell in this cluster must match that handshake or the system flags it as unknown.
- Bench tested on actual hardware: We ran this cell on a Satellite 5205 unit and confirmed the BMS initialised correctly on first connect, charge accepted from 0% without interruption, and the fuel gauge IC tracked draw accurately by the second full cycle.
- Post-install recalibration on the Satellite 5200 series: After fitting this battery, run one full discharge until the laptop hibernates on low voltage, then charge uninterrupted to 100% before use. 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 immediately after replacement
The Satellite 5200 series stores battery health data in EEPROM on the old cell. When a new cell is installed, the BIOS reads stale EEPROM values and flags the battery as degraded before it has ever been cycled. This is not a fault with the replacement cell — it is a firmware artefact from the previous battery's history. Running one full discharge-to-hibernate followed by a complete uninterrupted charge forces the BIOS to rewrite its learned capacity data against the new cell. After two full cycles, the health indicator should normalise.
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 actual voltage curve. Under combined CPU and display load, the cell voltage drops faster than the gauge predicts, and the laptop hits the hardware low-voltage cutoff while the OS still shows charge remaining. It is not a dead cell — it is a calibration gap between the gauge IC and the new chemistry. Force the gauge to relearn by running two full discharge cycles down to hibernate cutoff, then charging to 100% each time. After the second cycle, the shutdown threshold typically aligns with an accurate remaining percentage near 5–8%.