What should alternator charge at idle?

ALTERNATOR CIRCUIT VOLTAGE DROP TESTS With the engine idling, touch one test lead of your voltmeter to the battery positive (+) post, and the other test lead to the BAT (B+) terminal on the alternator. Ideally, the voltmeter should read less than 0.2 volts.

What should alternator voltage be when car is off?

With the engine off, battery voltage should be between 12.5 and 12.8 volts. If it’s below that, charge the battery with a battery charger before you conduct the test again. Then start the engine and check for increased voltage readings. If you see higher readings, chances are the alternator is good.

Why is my alternator only putting out 12v?

The only thing it might be is a bad voltage regulator, a component that’s attached to and normally considered part of the alternator. There’s no other components that turns the alternator on and off.

Is it normal for an alternator to not charge all the time?

Still, it’s perfectly normal for others to see the alternator not charge at all intermittently. One test is not enough if you are diagnosing a charging system problem. All too often, the alternator is condemned as the source of the problem if only battery voltage is present with the engine running.

What should the voltage be at the battery and alternator?

Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other. If the voltage at the battery and alternator don’t match. For example the battery reads 12v and alternator reads 14v. This means that there is an issue with wiring. While applying the same conditions as above.

What should the charging voltage of a car battery be?

There are two things that you are looking for. The charging voltage should be between 13.9v to 14.4v. Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other. If the voltage at the battery and alternator don’t match.

How do I know if my alternator is bad?

There are two simple tests for checking your alternator. Test 1: While your car is running, disconnect the positive battery cable. If the vehicle continues to run, your alternator is properly charging the battery. Test 2: When you start up your car, look at your interior lights.