Dear Tom and Ray:

On the dashboard of my 1990 Plymouth Voyager is a dial with a picture of a battery. The numbers show a range from 8 to 18. What is this gauge, and what is it trying to tell me? -- James

Ray: It's your voltmeter, James. And it's trying to tell you that they had extra space on the Voyager dashboard and that some supplier was having a special on voltmeters in 1989.

Tom: It's supposed to tell you how many volts of electricity your car's charging system is producing.

Ray: Under normal conditions, it should read between 12 and 14 volts.

Tom: The electricity to start the car comes from the battery. But once the engine is running, the belt-driven alternator takes over. It not only produces electricity for the ignition, lights and other accessories, but it also produces enough electricity to recharge the battery -- so you'll be able to start the car again next time.

Ray: And a voltage regulator -- another piece of the charging system -- tells the alternator how much charging the battery needs, and therefore, how much electricity to produce.

Tom: When the battery is low, the alternator will produce a little more than 14 volts.

Ray: When the battery is charged up, only about 12 volts will be produced.

Tom: If your voltmeter occasionally reads less than 12 volts, that's probably nothing to be alarmed about. If you have the lights on, the windshield wipers going and the air conditioner on, and you're sitting at idle, a temporary drop below 12 may just mean that you're using a lot more electricity than the alternator can produce at that low speed.

Ray: But if the gauge ever stays above 14 1/2 or drops below 12 for a long period of time, then you either have a problem with your charging system, or you have a problem with that 89-cent voltmeter they slapped in your car. And only an accurate test at your mechanic's shop can tell you for sure.

It's NEVER cheaper in the long run to buy a new car. Want proof? Order Tom and Ray's pamphlet How to Buy a Used Car: Things That Detroit and Tokyo Don't Want You to Know. To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 1997 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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