IBM and Lenovo Group has recalled 526,000 Sony batteries for ThinkPad notebooks, becoming the latest vendors to act on fire-prone power sources.

The companies advised owners of the batteries, which were sold worldwide with ThinkPads and as replacement units between February 2005 and September 2006, to return them to Lenovo for a free replacement. Lenovo took over IBM's PC division in May 2005.

The voluntary recall was announced in conjunction with the US Consumer Product Safety Commission (CPSC) after reports this month of a ThinkPad smoking and catching fire as a user was boarding an airliner at Los Angeles International Airport, the companies said in a statement. Apple Computer, Dell and Toshiba have also recalled Sony notebook batteries this year.

The batteries recalled were sold worldwide with T Series (T43, T43p and T60), R Series (R51e, R52, R60 and R60e) and X Series (X60 and X60s) ThinkPads or as replacement batteries for those units. The recall offer is open-ended, according to Lenovo.

The company is confident no other batteries will have the overheating problem, Lenovo spokesperson, Ray Gorman, said. Ever since the Apple and Dell problems came to light, Lenovo has been talking with the CPSC and studying its batteries, Gorman said. The notebook involved in the airport incident, a ThinkPad T43, is in Lenovo's main notebook lab in Yamato, Japan, undergoing tests.

The last of the affected batteries were actually shipped in July, but Lenovo extended the timeframe for its customer alert to September because the manufacturer can't be sure how long each notebook was in the sales channel before being sold, Gorman said.

A majority of ThinkPad batteries come from Sanyo Electric, according to Gorman, but the company also uses Panasonic and Sony units.

The notebooks involved in the recall were only a small fraction of those in owners' hands, IDC analyst, Richard Shim, said. During that period, the companies sold about 8.1 million ThinkPads worldwide, he said.

Anybody shopping for a ThinkPad today probably didn't have to worry about getting one that was affected by this recall, Shim said. However, they didn't really have any choice but to get the same basic battery technology. Lithium-ion was used by all the major vendors.

"Battery technology evolves very slowly," Shim said. One reason is that margins on batteries are thin. What manufacturers can do to increase safety is use better components with the same underlying system, he said.

The recalls come at a critical time for notebook makers, he said.

"We're heading into the big holiday season, and consumer notebooks are driving the PC industry from a growth perspective," Shim said.

Sony also announced plans for its own battery replacement program to address the kinds of cells involved in the Dell and Apple recalls. It will cooperate with other vendors that used the cells.