What should a good alternator test at?

Make sure your alternator’s positive and negative terminals are clean. Put the multimeter’s black cable to the negative terminal and the red cable to the positive terminal. Look for an ideal alternator reading of around 12.6. Start the car, and look for a reading of between 14.2 and 14.7.

Do you take the positive or negative off to test the alternator?

If you’re tempted to test an alternator by disconnecting the negative battery cable, don’t do it. A good alternator may indeed keep the engine running without the negative cable, but this was never a good test. In the pre-computer days, you could pull it off without damaging anything.

How many volts should an alternator put out at idle?

Most alternators that are charging properly should produce a voltage of about 13.8 to 14.2 volts at idle with the lights and accessories off.

Which battery cable do you take off to test the alternator?

Do I disconnect the positive or negative to check the alternator? Disconnect the negative battery cable before testing an alternator. Instead, use a voltmeter to perform a basic and safe test.

What should alternator voltage be at idle?

Which battery terminal do you disconnect to test the alternator?

Disconnect the negative battery cable before testing an alternator.

How do you check an alternator without a voltmeter?

You can still check an alternator without a multimeter if you don’t have any available.

  1. Start the car and rev the engine to 2000 RPM.
  2. Open the hood and listen closely to the alternator while the engine is idling.
  3. Switch your car radio to the lowest frequency on the AM band, then lower the volume.

How to test an alternator?

How To Test An Alternator 1 Remove battery terminals and make sure these are 100% clean from and buildup of corrosion. 2 Test the battery voltage, at rest this should read between 12.5 and 12.8V on average. 3 Check over all vehicle grounds to ensure these are up to par.

How much does an alternator load tester cost?

Proper load testers, normally found at professional shops and dealerships, cost around $2000 on the low end, not exactly cheap enough for the average DIYer. But there are still a few low-budget methods you can try to give you a good idea of the health of your alternator.

What should the voltage be on an alternator on a multimeter?

Testing an AlternatorIf the alternator is working well, your multimeter should read somewhere in the vicinity of 14 volts (typically 13.8-14.2). If it is reading excessively higher than 14 volts (greater than 15 volts), it is possible that the voltage regulator on your alternator is faulty or going bad.

How do alternator problems manifest themselves?

There are different ways by which problems with the alternator can manifest themselves. These are often dependent on the type of problem or issue that this part of the automobile has. The good thing is that assessing the presence of an alternator problem is quite easy.