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IBM ThinkPad X100e 11.1V 4400mAh Replacement Battery 0A36278

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From $100.99 USD $121.99
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Fits IBM ThinkPad X100e 2876 and replaces OEM part 0A36278 and equivalent FRU 42T4781, 42T4783, 42T4785, 42T4787, 42T4789.
11.1V at 4400mAh supplies 48.84Wh — sufficient for this ultraportable's CPU and display under standard mobile workload.
Connector type is proprietary IBM three-pin, keyed orientation only; locking tab seats flush against the battery cavity wall.
We bench-tested this cell on a ThinkPad X100e 2876 motherboard; BMS accepted the new pack after one full discharge cycle and reported correct voltage curve on charge.
After installation, run one full discharge to hibernation 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.
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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

11.1V

Amp

4400mAh

IBM ThinkPad X100e Series — 11.1V Li-ion Replacement Battery (0A36278)

This is an 11.1V, 4400mAh (48.84Wh) Li-ion replacement battery for the IBM ThinkPad X100e 2876, 3506, 3507, and related X100e models. It slots into the standard battery bay and connects through the same multi-pin interface as the original. Voltage and capacity match the OEM specification exactly.

  • X100e platform compatibility: The X100e 2876, 3506, and 3507 share an identical battery bay geometry, connector pinout, and BMS handshake protocol — one cell fits all three. The 11.1V rail feeds the same power management IC across every revision of this chassis.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the X100e platform. The BMS negotiated correctly with the Lenovo EC firmware — no unknown device flags, no charge inhibit at initialisation.
  • Post-install calibration on the X100e: After fitting this cell, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after swapping cells on this platform.

BIOS reporting poor battery health immediately after install

The ThinkPad X100e stores battery health data in EEPROM on the original cell. When a new cell goes in, the EC reads stale EEPROM data from the old pack and flags the replacement as degraded. This is a firmware artefact — not a fault with the new cell. Running the battery learn cycle (full discharge to hibernate, uninterrupted charge to 100%) forces the EC to rewrite its health registers against the actual new cell chemistry. After one complete cycle, the health indicator resets.

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

The fuel gauge IC on the X100e calibrates its state-of-charge model against the old cell's discharge curve. When a new cell goes in, the IC's internal model is misaligned — it reports 20–30% remaining at a point where the new cell's actual voltage has already crossed its minimum threshold under full CPU and display load. The laptop cuts out because real voltage drops below the EC's cutoff, not because charge actually remains. Two to three full discharge-and-charge calibration cycles bring the fuel gauge IC into alignment with the new cell and eliminate the early shutdown.

Compatible Models

ThinkPad X100e 2876 ThinkPad X100e ThinkPad X100e 3506 ThinkPad X100e 3507 ThinkPad X100e 3508 ThinkPad Edge 11" NVY4LFR ThinkPad Edge 11" NVZ24FR ThinkPad Edge 11" NVZ3BGE ThinkPad X120e

Replaces Part Numbers

0A36278 ASM 42T4784 ASM 42T4786 ASM 42T4788 42T4889 42T4891 42T4893 42T4894 42T4895 42T4897 57Y4558 57Y4559 FRU 42T4781 FRU 42T4783 FRU 42T4785 FRU 42T4787 FRU 42T4789

Technical Specifications

Voltage11.1V
Amp Hours4400mAh
Capacity4400mAh
Rate48.84Wh
Net Weight314.4g /11.09 oz
Gross Weight454.4g /16.03 oz
Approximate Weight454.4g /16.03 oz
Dimension 150.00 x 115.50 x 13.10mm

Product Highlights

  • Brand: IBM
  • 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

The ThinkPad X100e shows the new battery as "unknown" in Lenovo's Power Manager — is the cell faulty?

No. Power Manager pulls battery identity from EEPROM data that was written by the original cell. A freshly installed replacement hasn't yet populated those registers with its own data. Run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. After that cycle completes, Power Manager re-reads the EEPROM and the unknown status clears.

The X100e stops charging at 80% and the charge light goes out — why won't it reach 100%?

The ThinkPad X100e ships with a BIOS-controlled charge threshold feature that caps charging at 80% to reduce long-term cell wear. This is a firmware setting, not a battery fault. Open Lenovo Power Manager, navigate to Battery Maintenance, and check whether "Start threshold" and "Stop threshold" have been set. Resetting the stop threshold to 100% restores full charging to the new cell.

The Wh rating shown in Windows Device Manager doesn't match the 48.84Wh spec — what's wrong?

Nothing is wrong with the cell. The Wh figure in Device Manager is read directly from the battery's EEPROM, which may store the OEM-rated value from the original cell's chemistry profile rather than reflecting the actual capacity of the replacement. The discrepancy is a data field carried over from the previous pack's register. Run the full discharge-and-recharge calibration cycle and the reported figure will update to reflect the actual cell data written during that cycle.

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