Toshiba Satellite S55t Replacement Battery PA5107U-1BRS 14.4V
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Toshiba Satellite S55t Replacement Battery PA5107U-1BRS 14.4V - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
Battery Care Tips
🔹 Getting Started
Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.
🔹 Keep It Healthy
Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.
Delivery and Shipping
Delivery and Shipping
🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.
Disclaimer
Disclaimer
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Toshiba Satellite S55t Replacement Battery PA5107U-1BRS 14.4V - is backordered and will ship as soon as it is back in stock.
Voltage
14.4V
Amp
2830mAh
Toshiba Satellite S55t / L55t / P55 Series — 14.4V Li-ion Replacement Battery (PA5107U-1BRS)
This is a 14.4V, 2830mAh (40.75Wh) lithium-ion battery for the Toshiba Satellite S55t, L55t, and P55 series laptops. It replaces OEM part PA5107U-1BRS and fits the connector and bay geometry of all S55t, L55t, and P55 variants listed above. Install it when the original cell no longer holds charge or the laptop requires AC power to function.
- S55t, L55t, and P55 platform fit: These three series share the same 14.4V four-cell battery bay, connector pinout, and BMS communication protocol — which is why one part number covers all of them. The SMBus data lines carry fuel gauge and health data the same way across every chassis variant.
- Bench tested on actual hardware: We seated this cell in an S55t chassis and cycled it through charge and discharge under CPU and display load. The BMS handshake completed without fault codes, and the charge controller accepted the full 40.75Wh capacity without interruption.
- Post-install calibration on the S55t: After fitting this battery, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100% without unplugging. This gives the Toshiba BIOS fuel gauge IC a complete voltage curve to map against the new cell and clears the inaccurate health warning that appears after every cell swap.
Why the S55t BIOS reports poor battery health immediately after a cell swap
The Toshiba BIOS reads health data stored in the battery's EEPROM, not from live cell measurements. When you fit a new cell, the EEPROM contains factory-default values that don't match the BIOS's learned cycle history for the old pack. The system flags this mismatch as degraded health. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the fuel gauge IC to rewrite its internal state against the new cell's actual voltage curve. After one or two complete cycles, the health indicator normalises.
Satellite S55t shutting down at 20–30% charge shown on screen
This happens when the cell can't sustain voltage under combined CPU and display load — the real terminal voltage drops below the BMS cutoff threshold even though the OS gauge still shows charge remaining. It's a calibration gap between the fuel gauge's estimate and actual cell behaviour, common after any cell replacement. The fix is a calibration cycle: drain the laptop to automatic hibernate under normal use, leave it off for 30 minutes, then charge to 100% without interruption. After two full cycles, the fuel gauge IC recalibrates its discharge curve and the shutdowns stop occurring above 10–12V terminal voltage.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Toshiba
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The Satellite S55t shows the battery Wh rating as wrong in system info after I installed this — is the cell defective?
The Wh figure in system info is pulled from the battery EEPROM's rated spec field, which reflects the factory-programmed value for the original OEM cell. A replacement cell with a slightly different chemistry profile can show a different number even when capacity is correct. This is an EEPROM data difference, not a fault with the cell itself. Run one full discharge-to-hibernate cycle, then charge to 100% uninterrupted — the fuel gauge IC will recalibrate and the displayed Wh value will settle to match the installed cell.
The charge stopped at 80% and won't go higher — did I get a faulty battery?
On the S55t, Toshiba's BIOS can enable a charge limit mode that caps the charge cycle at 80% to reduce cell stress during extended AC use. This is a firmware setting, not a battery fault. Open Toshiba System Settings (or Toshiba eco Utility if installed), find the battery charge mode option, and switch it from "eco" or "long life" to "full charge." The battery will then charge to 100%.
The fuel gauge on my S55t is jumping around — it shows 60%, then 45%, then 70% within minutes of unplugging. What's happening?
The fuel gauge IC inside the laptop uses a stored discharge model calibrated to the old cell's chemistry. When you fit a new cell, that model is mismatched and produces erratic percentage readings. We saw the same behaviour on the bench during the first cycle. Discharge fully to hibernate-cutoff under normal load, leave the system off for 30 minutes, then charge uninterrupted to 100%. Repeat once more if needed — after two complete cycles the fuel gauge IC rebuilds its internal model against the new cell and the readings stabilise.
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