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Lenovo ThinkPad S440 Replacement Battery 14.8V 3100mAh 45N1140

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From $116.99 USD $140.99
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Fits Lenovo ThinkPad S440 and replaces OEM part numbers 45N1140, 45N1141, 45N1138, 45N1139, and 121500158.
14.8V at 3100mAh delivers 45.88Wh—enough charge capacity to match the original cell's runtime envelope on this ultraportable business laptop.
Connector slides into the rear battery slot with a keyed design; no adapter needed, and the locking tab seats flush when fully inserted.
We cycled this cell against the S440 motherboard and confirmed the BMS accepted the new pack on first charge without fault codes or voltage sag.
On first use, run one complete discharge to system shutdown, then charge uninterrupted to 100%—this resets the BIOS battery learn cycle and clears 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.

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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

14.8V

Amp

3100mAh

Lenovo ThinkPad S440 — 14.8V Li-Polymer Replacement Battery (45N1140)

This 14.8V, 3100mAh (45.88Wh) lithium-polymer cell replaces the original battery in the Lenovo ThinkPad S440 ultraportable business laptop. It fits all S440 variants, including the 20AY0019TW, 20AY003BCD, and 20AYA00DHH. Cross-reference OEM part numbers 45N1140, 45N1141, 45N1138, 45N1139, and 121500158 before ordering.

  • S440 platform compatibility: All ThinkPad S440 variants share the same 14.8V four-cell architecture, connector pinout, and BMS handshake protocol — which is why one cell covers the full model range without firmware differences between SKUs.
  • Bench tested on actual hardware: We ran this cell through full charge and load cycles on an S440 unit. The BMS negotiated correctly with the ThinkPad EC, charge termination triggered at the expected cutoff voltage, and the fuel gauge IC accepted the new cell without throwing a fault code on the first cycle.
  • Post-install recalibration on the ThinkPad S440: After fitting, run a single full discharge until the laptop hibernates at its low-voltage cutoff, 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 immediately after every cell swap on ThinkPad hardware.

BIOS reporting poor battery health right after fitting a new cell

The ThinkPad BIOS reads health data from the battery's EEPROM, which stores cycle count and capacity history from the previous cell. A brand-new cell still carries default EEPROM values that the BIOS interprets as degraded. This is not a fault with the replacement battery. Run the full discharge-to-hibernate, then charge-to-100% cycle described above — after one complete learn cycle, the BIOS recalculates health against actual measured capacity and the warning clears.

Laptop shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC's stored discharge curve no longer matches the actual voltage behaviour of the new cell. The gauge predicts 20–30% remaining, but the real cell voltage has already dropped below the load threshold under combined CPU and display draw — so the system shuts down to protect the hardware. It is not a defective battery. Two to three full calibration cycles — discharge to hibernate cutoff, charge fully to 100% each time — rebuild the fuel gauge model and bring the percentage readout back into accurate range.

Compatible Models

Thinkpad S440 ThinkPad S440 20AY0019TW ThinkPad S440 20AY003BCD ThinkPad S440 20AYA00DHH ThinkPad V4400u Thinkpad S440 20AY-001DMS Thinkpad S440 20AY Thinkpad S3-S440 Thinkpad S3-S431 ThinkPad S431

Replaces Part Numbers

45N1140 45N1141 45N1138 45N1139 121500158

Technical Specifications

Voltage14.8V
Amp Hours3100mAh
Capacity3100mAh
Rate45.88Wh
Net Weight244.5g /8.62 oz
Gross Weight504.5g /17.80 oz
Approximate Weight504.5g /17.80 oz
Dimension 301.42 x 68.84 x 7.64mm

Product Highlights

  • Brand: Lenovo
  • 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

The ThinkPad S440 BIOS shows the new battery as 0% or "unknown" right after I installed it — is the cell dead?

No. The BIOS reads state-of-charge from the battery's EEPROM, and a freshly installed cell often reports a default or uninitialised value until the first charge cycle completes. Plug in the AC adapter and let it charge uninterrupted to 100% without booting into Windows mid-charge. Once the cell reaches full voltage, the ThinkPad EC re-reads the EEPROM and the gauge populates correctly — if it still reads 0% after a full charge, check that the connector is fully seated and the locking tab has clicked.

System info shows the wrong Wh rating — it says something different from 45.88Wh after I swapped the battery.

The Wh figure shown in Windows or Lenovo Vantage comes from the EEPROM's rated-capacity register, not a live measurement. Different OEM part numbers in the 45N113x family were manufactured with slightly varied EEPROM presets even though the physical cell chemistry is the same. Run one full discharge-to-hibernate cycle followed by a full charge — after the learn cycle completes, the ThinkPad fuel gauge IC recalculates designed capacity against actual measured charge and the reported Wh figure updates to reflect the real cell.

The S440 charges to 80% and then stops — the battery never reaches 100%.

This is almost always the BIOS charge threshold feature, not a battery fault. Lenovo's power management firmware includes a conservation mode that caps charging at 80% to reduce cell stress during extended AC use — it is toggled independently of the battery itself. Open Lenovo Vantage (or the legacy Power Manager if running an older ThinkPad software stack), go to Battery Settings, and switch the charge threshold from Conservation Mode to the full-charge option. The battery will then charge to 100% on the next cycle.

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