Dear Tom and Ray:

My mother owns a Lexus. The Lexus dealer is telling her she must replace her aging battery with a Lexus battery, because others aren't "big enough." Is this true, or are they merely trying to take advantage of an older, non-car-savvy lady so they can sell her one of their own, much more expensive batteries? -- Melissa

TOM: Your mother can use any brand of battery she wants, Melissa.

RAY: As long as the battery meets the same specifications as the original battery that came with her Lexus (the same physical size, and a similar number of cold-cranking amps), she can put in a DieHard, an AC Delco, an Interstate or a boatload of Energizer D cells, and they'll all work just fine.

TOM: Well, not the D cells. But she should have no trouble finding an after-market battery that meets the specifications required by her Lexus. Most places that sell batteries have a chart where they can look up the year, make and model of a car, and tell your mom which batteries are appropriate for her car.

RAY: Batteries for nonhybrid cars are largely interchangeable, because the technology is all the same. There are a bunch of lead plates and about a two-liter bottle of sulfuric acid. The primary difference between batteries is the number of plates, which determines the amount of power the battery can store and deliver.

TOM: In fact, Melissa, Lexus doesn't even make its own batteries. It buys its batteries from somewhere else. So, why shouldn't your mom?