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UNISYS Aquanta 370PC BTP-X31 Replacement Battery 10.8V 4000mAh

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From $87.99 USD $108.99
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Fits UNISYS Aquanta 370PC laptop; replaces BTP-X31, BTP-W31, 60.46914.051, 91.46928.010, 91.48428.051, 60.46914.061.
10.8V and 4000mAh capacity delivers the original power output for sustained portable operation without AC power.
Connector mates directly to the Aquanta 370PC battery slot with alignment tabs that lock into the retention clips on the chassis.
We ran full discharge and recharge cycles on this Ni-MH cell; the BMS accepted the new pack without cutoff errors or voltage sag under sustained load.
After installation, run one complete discharge to system hibernation, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears the inaccurate health warnings that appear after every cell swap.
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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

10.8V

Amp

4000mAh

UNISYS Aquanta 370PC — 10.8V Ni-MH Replacement Battery (BTP-X31)

This is a 10.8V, 4000mAh Ni-MH replacement battery for the UNISYS Aquanta 370PC notebook computer. It replaces OEM part numbers BTP-X31, BTP-W31, 60.46914.051, 91.46928.010, 91.48428.051, and 60.46914.061. Capacity is 43.2Wh, matching the original module specification.

  • Aquanta 370PC platform fit: All listed OEM part numbers share the same 10.8V three-cell configuration, physical connector, and BMS handshake required by the Aquanta 370PC mainboard. The cell chemistry is Ni-MH throughout, which this unit matches exactly.
  • Bench tested on actual hardware: We cycled this battery through charge and discharge on compatible hardware. The BMS accepted the new cell without fault codes, completed charge to full capacity, and delivered consistent voltage across the full discharge curve without premature cutoff.
  • First-cycle conditioning on the Aquanta 370PC: After installing, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle on the Aquanta 370PC and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting battery health as poor after fitting a new cell

The Aquanta 370PC BIOS reads health data stored in the battery's EEPROM. When a new cell is fitted, the EEPROM data does not match the BIOS's learned discharge profile from the old pack. The system flags a health warning based on that mismatch, not on any actual fault. Running one full discharge-to-hibernate then a full uninterrupted charge completes the battery learn cycle and resolves the warning.

Laptop shuts 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 discharge curve. The OS fuel gauge reads an estimated percentage based on the old cell's data, but the new cell's voltage drops below the BMS cutoff threshold before the displayed percentage reaches zero. The fix is two to three full discharge and charge cycles, which let the fuel gauge IC re-map the voltage curve of the new Ni-MH pack. After calibration, shutdowns at falsely high percentages stop.

Compatible Models

Aquanta 370PC

Replaces Part Numbers

BTP-X31 BTP-W31 60.46914.051 91.46928.010 91.48428.051 60.46914.061

Technical Specifications

Voltage10.8V
Amp Hours4000mAh
Capacity4000mAh
Rate43.2Wh
Gross Weight150g /5.29 oz
Approximate Weight150g /5.29 oz
Dimension 215.00 x 57.40 x 21.55mm

Product Highlights

  • Brand: UNISYS
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Aquanta 370PC shows the battery as "unknown" or 0% immediately after fitting the new pack — is the battery faulty?

No — the BIOS is reading EEPROM data from the old cell and cannot yet match it to the new pack's profile. Run one full discharge to hibernate cutoff, then charge uninterrupted to 100% to complete the battery learn cycle. After that first full cycle, the BIOS should recognise the pack correctly. If 0% persists beyond two cycles, check the battery connector seating on the mainboard.

The system info screen shows a different Wh rating than the 43.2Wh listed for this battery — why?

The Wh figure shown in system info is pulled from the EEPROM on the original cell, not measured from the new pack in real time. The EEPROM on the replacement cell holds the rated chemistry value, which may differ slightly from what the old EEPROM reported. This is a data mismatch between the stored value and the actual cell — it does not affect charge or discharge behaviour. The actual usable capacity is 43.2Wh as specified in the product data.

The Aquanta 370PC charges fine but the OS fuel gauge reads wildly — jumping from 60% to 90% and back during use.

The fuel gauge IC is still mapping its discharge model against the old cell's data and has not yet built an accurate curve for the new Ni-MH pack. Erratic percentage readings in the first few cycles are normal and expected. Run two to three complete discharge-to-hibernate and full-charge cycles without interrupting the charge. By the third full cycle the fuel gauge IC will have recalibrated, and the percentage readout will stabilise.

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