By Molly Daly

PHILADELPHIA (CBS) — Thursday’s snow will be followed by biting cold, with the mercury forecast to dip into the single digits on Friday night.

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And that means a lot of cars will have trouble starting, or won’t start at all, according to AAA.

Jenny Robinson, a spokeswoman for AAA Midatlantic, says frigid temperatures take a major toll on automobile batteries.

“At zero degrees, a car’s battery loses about 60 percent of its strength, and at freezing it loses 35 percent,” she explains, because the cold slows down the battery’s ability to produce electrons.

And even when the engine is off, the battery must continue working, Robinson says:

“The battery continues to supply power to the clock, the anti-theft system, and all the other computerized conveniences in modern cars.”

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She says your battery has ways of telling you it’s in trouble: a grinding or clicking sound when you turn the ignition; the engine cranks slowly; the headlights dim when idling but brighten when you rev the engine; and its age.

“The life span of an automotive battery is usually three to five years, but when you have the toll taken by the cold weather, the hot weather we had over the summer, and the more demanding electrical systems in all the on-board computers and devices that we charge, that can take a toll on the life fo the battery,” Robinson tells KYW Newsradio.

She says it’s best to find out now if your battery is up to snuff.

“You can get it tested. AAA facilities will do that for free, and some other places might as well,” she says.

And even if it does cost you a bit for testing, it’s a good bet it won’t be as much as a lost day of work because your car won’t start.

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