I bought an old IBM Thinkpad 240 (from the year 1999). The battery was almost dead, and lastest only 3 seconds.

I am planning on replacing the cells, and want to document everything here.

FRU: 02K6606

Battery Controller: bq2040

Battery EEPROM: 24C01

The bq**** and 24C01 EEPROM are a commonly seen combination in older IBM Thinkpads, an X30 battery I disassembled had a similar controller (bq9011DBT), and a 24C01 EEPROM.

The battery cells (3x, wired in series) are LiIon, rectanglar type, labeled with DG2PB6.

Battery Cell dimensions:

• Width: 34mm
• Length: 48mm
• Thickness: 10mm

From the look and dimensions, it seems that UF103450P is a suitable replacement type.

If you are doing this yourself, under no circumstances(!!) disconnect the battery control PCB from the cells. Do not allow the controller to be powered off, otherwise it will lock you out, even if you install new cells. The battery will only discharge once, and not charge without reprogramming the EEPROM.

I intend to do a “hot swap”: solder on the new cells while the old ones are still connected. Remove the old cells afterwards.