Apple Computer said yesterday it is recalling 1.8 million laptop batteries because they can overheat and cause fires — the same problem that caused Dell to recall 4.1 million batteries last week.

The Apple and Dell batteries were made by Sony and share the same flaw. Tiny metal impurities can, in rare cases, damage safeguards designed to prevent overheating. Apple says it has received nine reports of overheating, two of which caused minor burns.

The Apple recall is limited to several iBook G4 and PowerBook G4 models sold from October 2003 to August 2006. None of Apple's new laptops, which use processors from Intel, are affected, spokesman Steve Dowling says.

Sony spokesman Rick Clancy says the problem was caused by flaws in the manufacturing process that have been corrected. Sony expects to spend $172 million to $258 million on the recalls.

The Japanese electronics giant makes battery components for many other PC makers, including Hewlett-Packard. Sony has been talking to these customers, and does not expect them to be affected, because each builds its batteries and related parts a little differently.

The Consumer Product Safety Commission, spearheading the recalls in the United States, agrees. But spokeswoman Julie Vallese noted that the commission's decisions "are based on information we have on hand at any particular day."

Analysts say it might not be so simple. "Sony battery impurities are strewn across the land," says tech analyst Roger Kay, with researcher Endpoint Technologies Associates.

Battery problems are tough for researchers to replicate, Kay says. They know impurities are a factor, but it has been tough to figure out what else must happen to make one overheat, Kay says. In most cases, impurities would cause the battery to short out and turn off.

There were only 15 reports of overheating among the 5.9 million Apple and Dell batteries recalled. That's an incident rate of 0.0003 percent.

Other PC makers say they're comfortable with their tests. Lenovo has tested its PCs in partnership with Sony, and is planning no recall, says spokesman Bob Page.

HP, Gateway, Toshiba and Acer also say their batteries are fine.

Still, the bad press could ding fast-growing laptop sales during the crucial back-to-school and holiday shopping seasons, says tech analyst Richard Shim with researcher IDC.