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Lenovo ThinkPad E120 Replacement Battery 11.1V 4400mAh

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New arrival
From $77.99 USD $95.99
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Fits Lenovo ThinkPad E120 30434NC, replaces OEM part 0A36290, 0A36292, 42T4943, 42T4945, 42T4949, 42T4951, and 45N1056 through 45N1059.
11.1V, 4400mAh lithium-ion cell delivers 48.84Wh — sufficient for full workday runtime on E120 models without midday recharge cycles.
Connector seats flush into the battery bay slot; locking tab engages at the rear edge to secure the pack against vibration during transport.
We bench-tested this cell on an E120 load profile — BMS discharged cleanly to cutoff and accepted charge current without throttling or fault codes on insertion.
After installation, run one full discharge cycle to system hibernation, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on Lenovo machines.
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

11.1V

Amp

4400mAh

Lenovo ThinkPad E120 Series — 11.1V Li-ion Replacement Battery (0A36290)

This 11.1V, 4400mAh (48.84Wh) Li-ion battery replaces the original cell in the Lenovo ThinkPad E120 and ThinkPad Edge E120 series notebooks. It covers OEM part numbers including 0A36290, 42T4943, 45N1058, and related variants. Install it when the original cell no longer holds sufficient charge for portable use.

  • ThinkPad E120 and Edge E120 compatibility: These models share the same 11.1V three-cell architecture, connector pinout, and BMS handshake protocol — meaning one cell covers the full variant range including the 30434NC, 30434SC, and 30434TC chassis without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a ThinkPad E120 unit. The BMS negotiated correctly with the EC, charge current tapered normally at the top of the curve, and the protection circuit tripped cleanly at the low-voltage threshold.
  • Post-install discharge cycle: After fitting this cell, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.

BIOS reporting poor battery health immediately after fitting a new cell

The ThinkPad EC reads health data from the battery's EEPROM and compares it against stored charge history from the previous cell. A brand-new cell has no accumulated cycle data, so the EC flags it as degraded — this is a data mismatch, not a fault with the replacement. Running the BIOS battery learn cycle writes fresh baseline data from the new cell. After one full discharge-to-hibernate and an uninterrupted charge to 100%, the health indicator updates and the warning clears.

Laptop shuts down abruptly 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 gauge loses accuracy under combined CPU and display load — voltage drops faster than the IC predicts, and the protection circuit cuts power before the displayed percentage reaches zero. It is not a faulty cell. Run two to three full discharge-to-hibernate cycles to let the IC map the real capacity curve. After calibration, the cutoff point will align with the displayed percentage at or below 5%.

Compatible Models

ThinkPad E120 30434NC ThinkPad E120 30434SC ThinkPad E120 30434TC ThinkPad Edge E120 ThinkPad Edge E125 ThinkPad Edge E320 ThinkPad Edge E325 Thinkpad E120 ThinkPad X121e ThinkPad X130e ThinkPad Edge E330 ThinkPad Edge E335 Thinkpad Edge E130 Thinkpad Edge E135 Thinkpad Edge E145 Thinkpad Edge L330 Thinkpad X131e Thinkpad X140e

Replaces Part Numbers

0A36290 0A36292 42T4943 42T4945 42T4949 42T4951 AM 42T4948 ASM 42T4958 ASM 42T4960 ASM 42T4962 FRU 42T4947 FRU 42T4957 FRU 42T4959 FRU 42T4961 ASM 42T4948 ASM 45N1058 FRU 45N1059 42T4950 42T4952 3INR19-65-2 42T4947 42T4948 42T4957 42T4958 42T4959 42T4960 42T4961 42T4962 45N1056 45N1057 45N1058 45N1059

Technical Specifications

Voltage11.1V
Amp Hours4400mAh
Capacity4400mAh
Rate48.84Wh
Net Weight300g /10.58 oz
Gross Weight450g /15.87 oz
Approximate Weight450g /15.87 oz
Dimension 206.90 x 55.20 x 20.50mm

Product Highlights

  • Brand: Lenovo
  • 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

Why does my ThinkPad E120 show the battery Wh rating as wrong in system information after fitting the new cell?

The Wh figure in system info is pulled from the EEPROM on the battery pack, not measured in real time. A new cell's EEPROM reports its rated chemistry spec, which can differ slightly from the previous pack's stored value — the EC displays what it reads, not what the cell is actually delivering. This is a data display issue, not a capacity fault. Run the BIOS learn cycle — one full discharge to hibernate, then a complete uninterrupted charge — and the system will re-read and settle on the correct 48.84Wh figure.

The fuel gauge on my ThinkPad E120 is jumping around wildly for the first few charge cycles — is the replacement cell faulty?

The fuel gauge IC on this platform needs several full cycles to build an accurate model of the new cell's discharge curve. Until it does, the percentage display can skip, jump, or stall — particularly between 60% and 30%. We see this consistently on first and second cycles during bench testing. Run three complete discharge-to-hibernate and full-charge cycles without interruption and the gauge IC will stabilise.

My ThinkPad E120 won't charge past 80% even though the battery indicator shows it's still charging — what's happening?

Lenovo's BIOS on this platform includes a charge threshold firmware setting that caps charging at 80% when the battery conservation mode is active. This is a BIOS-controlled limit, not a fault in the replacement cell. Open Lenovo Vantage or ThinkPad Battery Manager, navigate to the battery charge threshold settings, and set the stop-charge value to 100% to restore full charging capacity.

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