Sony VAIO VGN-FZ15 Replacement Battery 11.1V 4400mAh VGP-BPS8
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Sony VAIO VGN-FZ15 Replacement Battery 11.1V 4400mAh VGP-BPS8 - 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
⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.
🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Sony VAIO VGN-FZ15 Replacement Battery 11.1V 4400mAh VGP-BPS8 - is backordered and will ship as soon as it is back in stock.
Voltage
11.1V
Amp
4400mAh
Sony VAIO VGN-FZ15 Series — 11.1V Li-ion Replacement Battery (VGP-BPS8)
This is an 11.1V, 4400mAh (48.84Wh) Li-ion replacement battery for the Sony VAIO VGN-FZ15 series notebook. It fits the VGN-FZ15, VGN-FZ15G, VGN-FZ15L, VGN-FZ15M, and over 235 additional VAIO models that use the VGP-BPS8, VGP-BPS8A, VGP-BPS8B, VGP-BPL8, or VGP-BPL8A part numbers. Dimensions are 137.00 × 78.80 × 20.60mm — physically identical to the original pack.
- VGN-FZ series compatibility: Every model in this range runs an 11.1V three-cell rail with the same dock connector and BMS handshake protocol. The VAIO SMBus talks to the battery's protection circuit on pin contacts at a fixed address — so any cell in this group either communicates correctly or it doesn't charge at all. This pack uses the same address and protocol.
- Bench tested on actual hardware: We ran this cell on a VGN-FZ series unit and monitored the BMS handshake through the full charge cycle. The protection circuit responded to Sony's charge controller without negotiation errors, and the pack held steady voltage under combined CPU and display load without triggering undervoltage cutoff.
- First-cycle recalibration on the VGN-FZ15: After installing, run one complete discharge down to hibernate-cutoff, then charge uninterrupted to 100%. The VAIO's battery learn cycle uses that data to reset its internal fuel gauge IC. Skipping this step causes the BIOS to carry over EEPROM state from the old pack and report inaccurate charge percentages for weeks.
Why the VGN-FZ15 BIOS flags a new battery as poor health immediately after swap
The VAIO's battery health indicator reads EEPROM data written by the original cell over its lifespan — cycle count, degradation flags, and rated Wh. When a new pack installs, that EEPROM presents a fresh state that doesn't match the historical data the BIOS cached from the old battery. Sony's firmware interprets the mismatch as a suspect cell rather than a new one. Running one full discharge-to-hibernate then a complete uninterrupted charge resolves this — the BIOS overwrites its cached data with the new cell's actual readings and the health warning clears.
VGN-FZ15 shutting down abruptly at 20–30% charge remaining
This happens when the cell voltage drops below a sustainable threshold under combined CPU, display, and I/O load — even though the fuel gauge still shows 20–30% remaining. Aged or shallow-cycled cells lose the ability to sustain voltage under real draw, hitting the BMS undervoltage cutoff before the displayed percentage reaches zero. The fuel gauge IC has not yet calibrated its discharge curve to the new cell's chemistry. After two full discharge-to-hibernate and charge-to-100% cycles, the gauge recalibrates and the shutdown point shifts back toward 0–5% as expected.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Sony
- Manufacturer: CS
- Series: Standard
- Color: Silver
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The VAIO shows the battery Wh rating as different from what I ordered — is the cell wrong?
The Wh figure shown in Sony's battery info panel pulls from the EEPROM on the cell, which stores the manufacturer's rated capacity at the time of production. Our replacement cell is rated at 48.84Wh, but the EEPROM value the OS reads may display slightly differently depending on how Sony's firmware rounds and interprets it. This is an EEPROM reporting difference, not a capacity fault. Check the physical label on the cell — if it reads 4400mAh / 11.1V, the cell is correct.
The charge percentage on the VGN-FZ15 jumps around wildly — showing 60%, then 85%, then 45% within minutes of unplugging.
The fuel gauge IC on this platform calibrates its discharge curve against the specific cell it's tracking. After a battery swap, the IC has no learned data for the new cell and interpolates badly, producing erratic percentage readings. Run two full discharge cycles to hibernate-cutoff followed by uninterrupted charges to 100%. After the second cycle, the IC will have enough discharge data to map the curve accurately and the percentage will stabilise.
The VGN-FZ15 stopped charging above 80% — the bar just sits there and never moves.
Some VAIO BIOS versions ship with a battery care or charge limiter setting enabled by default — this caps charging at 80% to reduce cell stress during regular desk use. Check Sony's VAIO Control Center or the BIOS power management screen for a "Battery Care Function" or charge limit toggle. Disable it, then reconnect the AC adapter. The charge bar should resume climbing toward 100% within a few minutes.
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