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Sony VAIO A12 Replacement Battery VJ8BPS55 7.6V 3100mAh

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From $70.99 USD $87.99
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Replaces Sony VJ8BPS55 battery in VAIO A12 ultraportable notebooks.
7.6V at 3100mAh delivers 23.56Wh to restore full charge cycles on aging VAIO A12 systems.
Connector seats flat into the battery slot with a single locking tab on the left edge.
We ran a full discharge-to-hibernation cycle followed by uninterrupted charge to 100%; the BMS settled voltage at 8.4V peak with no early cutoff.
After installation, run one complete discharge cycle to hibernation cutoff then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears inaccurate health warnings that appear after cell swaps.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

🔹 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.

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⚠️ 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.

Voltage

7.6V

Amp

3100mAh

Sony VAIO A12 — 7.6V Li-Polymer Replacement Battery (VJ8BPS55)

This is a 7.6V, 3100mAh (23.56Wh) lithium-polymer battery for the Sony VAIO A12 ultraportable laptop. It replaces OEM part number VJ8BPS55 and fits the VAIO A12 series directly. Cell degradation and capacity fade are the most common reasons owners replace this battery.

  • VAIO A12 fitment: The A12 uses a flat Li-Polymer pack with a specific connector pitch and BMS handshake tied to the VJ8BPS55 part number. Swapping to a cell that matches this spec keeps the firmware communication intact and prevents false fault codes on boot.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on VAIO A12 hardware and confirmed the BMS negotiation completed without error. The protection circuit held cutoff voltage correctly at both ends of the cycle.
  • First-cycle recalibration after install: After fitting this battery, run the laptop down to hibernate-cutoff under normal use, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears after every cell swap.

Why the VAIO A12 shuts down at 20–30% after a battery swap

The VAIO A12 fuel gauge IC calibrates against the previous cell's charge curve. When a new cell goes in, the stored curve no longer matches actual cell voltage under load. Under full CPU and display draw, the new cell hits a voltage cliff the old curve doesn't account for, and the system interprets it as empty. Running two to three full discharge-to-hibernate cycles recalibrates the IC against the new cell's actual curve and stops premature shutdowns.

BIOS reporting battery health as poor or unknown after replacement

The VAIO A12 BIOS reads health data from EEPROM stored in the original battery pack. A replacement cell carries different EEPROM values, which the BIOS flags as degraded or unrecognised on first boot. This is a firmware mismatch, not a fault with the new cell. Run the battery learn cycle — discharge fully to hibernate, then charge to 100% without interruption — and the health status will update to normal within one to two cycles.

Compatible Models

VAIO A12

Replaces Part Numbers

VJ8BPS55

Technical Specifications

Voltage7.6V
Amp Hours3100mAh
Capacity3100mAh
Rate23.56Wh
Net Weight105.8g /3.73 oz
Gross Weight245.8g /8.67 oz
Approximate Weight245.8g /8.67 oz
Dimension 141.10 x 139.00 x 2.86mm

Product Highlights

  • Brand: Sony
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My VAIO A12 is showing the wrong Wh rating in system info after swapping the battery — is something wrong with the cell?

The Wh figure shown in Windows or BIOS is pulled from the battery's EEPROM, which stores the rated capacity of the original cell. A replacement cell carries its own EEPROM value, and if it differs from what the firmware expects, the displayed Wh will be off. This is a reporting discrepancy between stored data and actual chemistry — it does not affect how the battery charges or discharges. Run a full discharge to hibernate and a complete charge to 100% to let the fuel gauge IC recalibrate against the actual cell.

The fuel gauge on my VAIO A12 is jumping around wildly — it reads 60%, then 45%, then 70% within minutes.

The fuel gauge IC on the A12 learns the cell's charge curve over several cycles. With a new cell installed, it has no accurate curve data yet, so it interpolates badly and produces erratic readings. This is normal for the first two to three cycles and settles once the IC has mapped the new cell's actual voltage behaviour. Discharge fully to hibernate-cutoff and charge uninterrupted to 100% twice, and the gauge will stabilise.

My VAIO A12 replacement battery stopped charging above 80% and just sits there — charger is fine.

The VAIO A12 BIOS includes a charge limit feature that caps charging at 80% when battery care mode is active. This is a firmware-controlled setting, not a fault with the cell or charger. Open VAIO Control Center or check the power settings in Windows for a "Battery Care Function" or charge limit toggle. Disable it, then reconnect the charger — the battery will charge to 100%.

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