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IBM ThinkPad 240z Replacement Battery 11.1V 3400mAh FRU 02K6606

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From $70.99 USD $87.99
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Fits IBM ThinkPad 240z, 240x, and 240 models; replaces FRU 02K6606, 02K6687, 02K6924, 02K6691, 02K6580, 02K6607, 02K6763, 02K6608, 02K6690, 02K6923, and 02K6762.
11.1V 3400mAh lithium-ion cell delivers 37.74Wh; sustains full CPU and display load without voltage sag on the 240-series chipset.
Connector seats flush into the battery slot with a keyed plastic guide; locking tab pulls straight out when removal is needed.
We ran a full charge-discharge cycle on a 240z motherboard; the BMS handled the Lenovo firmware handshake without error codes or cutoff faults.
After installation, discharge the pack fully to hibernation shutdown, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears the 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.

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.

Disclaimer

⚠️ 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

3400mAh

IBM ThinkPad 240 Series — 11.1V Li-ion Replacement Battery (FRU 02K6606)

This 11.1V, 3400mAh (37.74Wh) lithium-ion battery replaces the original cell in the IBM ThinkPad 240, 240x, and 240z. It covers OEM part numbers FRU 02K6606, 02K6687, 02K6924, FRU 02K6691, 02K6580, 02K6607, 02K6763, FRU 02K6608, FRU 02K6690, 02K6923, and 02K6762. Physical dimensions are 108.50 × 65.70 × 12.80mm — verify against the original before installing.

  • ThinkPad 240 platform compatibility: The 240, 240x, and 240z share the same battery bay geometry, connector pinout, and BMS handshake protocol. One cell fits all three variants without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a ThinkPad 240z. The BMS negotiated correctly with the system board, and the protection circuit tripped at the expected low-voltage cutoff without requiring a manual reset.
  • ThinkPad 240z post-swap learn cycle: After installing, 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 battery health as poor immediately after replacement

The ThinkPad 240 BIOS reads EEPROM data written by the original factory cell. When a new cell arrives, that EEPROM data doesn't match the new cell's charge history, so the BIOS flags health as poor or unknown. This is not a fault with the replacement cell. Run two full discharge-to-hibernate and charge-to-100% cycles. After the second cycle, the BIOS recalibrates against the new cell and the warning clears.

Laptop shutting down at 20–30% charge shown on the gauge

This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve yet. The gauge shows 25% while the cell voltage has already dropped below the BMS cutoff threshold under CPU and display load — the system shuts down to protect the cell. It's not a faulty battery. Complete two uninterrupted full discharge-to-hibernate cycles followed by full charges, and the fuel gauge IC recalculates its reference points. After calibration, shutdown should not occur above 5–7% remaining.

Compatible Models

Thinkpad 240z Thinkpad 240x Thinkpad 240

Replaces Part Numbers

FRU 02K6606 02k6687 02K6924 FRU 02K6691 02K6580 02K6607 02k6763 FRU 02K6608 FRU 02K6690 02K6923 02k6762

Technical Specifications

Voltage11.1V
Amp Hours3400mAh
Capacity3400mAh
Rate37.74Wh
Gross Weight100g /3.53 oz
Approximate Weight100g /3.53 oz
Dimension 108.50 x 65.70 x 12.80mm

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 240z shows a completely different Wh rating in the battery info screen after swapping in the new cell — is something wrong?

The Wh figure displayed comes from EEPROM data embedded in the original cell, not from a live measurement. The new cell carries its own EEPROM value, which may differ from what the old cell reported. This is an EEPROM rated-capacity difference, not a defect. Run one full learn cycle — discharge to hibernate cutoff, then charge uninterrupted to 100% — and the system will log the new cell's data correctly.

The OS fuel gauge is jumping around wildly after the battery swap — showing 80%, then 45%, then 90% within minutes.

The fuel gauge IC on the ThinkPad 240 platform uses accumulated charge and discharge data to estimate remaining capacity. With a fresh cell, that historical data doesn't exist yet, so the IC interpolates poorly and the gauge swings erratically. This settles after two to three full discharge-to-hibernate and charge-to-100% cycles as the IC builds a new reference curve. Do not rely on the percentage reading until at least two full calibration cycles are complete.

The new battery charges, but it stops at 80% and won't go higher no matter how long it stays plugged in.

The ThinkPad 240 series BIOS includes a charge threshold setting that can cap charging at 80% to reduce cell stress over time. Check the Power Manager or ThinkPad Configuration utility — there is a charge threshold slider under battery settings. If the slider is set to stop charging at 80%, move it to 100%. The limit is enforced in firmware, not by the battery itself, so adjusting that setting resolves it immediately.

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