When it comes to batteries, it’s a brave new world in a service bay. “The days of standard alternator output — it’s good if it is between XX.X and YY.Y volts — across all makes and models are over,” says Jim O’Hara, vice president of marketing for Clore Automotive Inc.

All but the youngest drivers remember when a slow cranking start or dim headlights signaled a dying battery. Those days are gone. Modern vehicles start instantly until — with no warning — they don’t. Many no-start problems occur when temperatures drop just a few degrees.