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IBM Thinkpad 240z Replacement Battery 11.1V 1700mAh

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From $57.99 USD $71.99
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Replaces FRU 02K6608, FRU 02K6606, FRU 02K6690 in Thinkpad 240z, 240x, 240 ultraportables.
11.1V at 1700mAh delivers 18.87Wh — matches original output for full CPU and display load cycles.
Connector slides into original slot; tab locks down flush with no force needed on insertion.
We ran a full charge-discharge cycle; BMS held steady voltage under sustained load without early cutoff.
After install, run one full discharge to hibernate-cutoff then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears inaccurate health warnings that appear after 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

1700mAh

IBM ThinkPad 240 Series — 11.1V Li-ion Replacement Battery (FRU 02K6608)

This 11.1V, 1700mAh (18.87Wh) Li-ion battery replaces the original cell in the IBM ThinkPad 240, 240x, and 240z. It fits all three models in this ultraportable series and matches the original voltage rail and connector. OEM part numbers covered: FRU 02K6608, FRU 02K6606, and FRU 02K6690.

  • ThinkPad 240 series fit: The 240, 240x, and 240z share the same battery bay dimensions, 11.1V rail, and connector pinout. One cell covers all three variants without modification.
  • Bench tested on actual hardware: We cycled this cell through charge, discharge, and load on the ThinkPad 240 platform. The BMS communicated correctly with the system board and held voltage stable under CPU and display load.
  • First-cycle reset on the 240 series: After fitting this cell, run the ThinkPad down to hibernate cutoff on battery alone — no AC. 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 after every cell swap.

BIOS reporting poor battery health immediately after fitting a new cell

The ThinkPad 240 BIOS reads health data stored in the outgoing cell's EEPROM, not from live voltage measurements. When a new cell goes in, that EEPROM data is gone and the BIOS flags the battery as degraded or unknown. This is not a fault with the replacement cell. One full discharge-to-hibernate followed by a complete uninterrupted charge rewrites the learn cycle and the health status updates correctly.

Laptop shuts down with 20–30% charge still showing on the gauge

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The gauge inherited the old cell's profile and calls the cutoff point too early. The ThinkPad 240 draws sharply under combined CPU and backlight load, exposing this mismatch faster than idle use would. Run two to three full discharge-to-hibernate and full-charge cycles — the gauge recalibrates and the premature shutdowns stop.

Compatible Models

Thinkpad 240z Thinkpad 240x Thinkpad 240

Replaces Part Numbers

FRU 02K6608 FRU 02K6606 FRU 02K6690

Technical Specifications

Voltage11.1V
Amp Hours1700mAh
Capacity1700mAh
Rate18.87Wh
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

My ThinkPad 240z shows the battery as "0%" or "unknown" right after I put in the new cell — is it dead?

It is not dead. The ThinkPad 240 BIOS reads health data from the EEPROM in the old cell. When that cell is gone, the BIOS has no reference and flags the new one as unknown or 0%. Run the laptop down to hibernate on battery only, then charge uninterrupted to 100%. That single learn cycle writes fresh data and the status clears.

The charge percentage jumps around wildly for the first few uses — it read 60% then jumped to 15% with no warning.

The fuel gauge IC on the 240 series is still using the discharge curve it learned from the old cell. Until it maps the new cell's actual chemistry over two or three full cycles, the readings are unreliable. Keep running full discharges to hibernate cutoff followed by full uninterrupted charges. By the third cycle the gauge tracks accurately and the erratic jumps stop.

System info shows the wrong Wh rating for this battery — the BIOS says something different from 18.87Wh.

The Wh figure in the BIOS comes from the rated capacity stored in the replacement cell's EEPROM, which reflects the chemistry specification rather than a live measurement. The actual delivered energy at 11.1V and 1700mAh is 18.87Wh. The discrepancy is a data field difference, not a fault. Check the displayed voltage instead — if the system reads 11.1V and the cell charges to full, the battery is functioning correctly.

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