via Traction Life

Are you a fan of the DIY methods? You know building, modifying, or repairing things by yourself without the direct aid of experts or professionals? Feeling that incomparable and unique sensation of satisfaction?

Well, if you’re feeling motivated, I bring to you how to test a car alternator without turning the engine off, thus without disconnecting your vehicle’s battery. And all the equipment you are going to need is a multimeter.

So, if you’re ever tempted to test an alternator by disconnecting the negative battery cable, don’t. We are going to use the multi-meter to conduct a simple, safe test. Check out these helpful steps that could come in handy during an emergency rush.


How To Test A Car Alternator

Step 1: Once you’ve opened your hood, make sure you have clear access to the car battery. Locate your car’s alternator and first check the alternator belt isn’t loose.

Step 2: Take your multimeter and turn it to the 20 V setting.

Step 3: Start the engine. By this point, it is important to make sure the alternator belt or pulley is spinning correctly without slipping.

Step 4: Remember you need to have easy access to the alternator. Make sure none of your body parts or clothing could get tangled in the spinning pulley. Once you’ve checked these security tips, place the positive multimeter probe (the one in red) and touch it to the red terminal connector that is coming out of the alternator.

Step 5: Now take the negative multi-meter probe (the one in black) and touch it to any metal part of your car frame (it could be a belt head or any other metal material nearby, it can also be the negative terminal on the car battery). However, do not ground to the alternator itself. That could be dangerous.

Step 6: After applying all the aforementioned steps, you will start getting a reading on your multi-meter screen.


The Results

via Cannon Auto Repair

If everything is okay and your car’s alternator is working properly, your multimeter should read somewhere in the vicinity of 14 volts (typically 13.8-14.2). If the reading goes excessively higher than volts (higher than 15 volts), it is possible that your car’s alternator is faulty or going bad.

However, if the reading displays numbers below 13-14 volts, it could mean either two things. One, it is possible that your engine idle speed is too low for the alternator to put out sufficient voltage/power. So you might want to rev up the engine to 2000 RPM or higher and take a reading one more time to the alternator.

The second reason could be that the voltage is still too low. You might want to check all the connectors on your alternator and make sure they are tight. The alternator belt shouldn’t be slipping. It should be spinning properly on the pulley. Nonetheless, if you’ve checked all this out and still there’s no sufficient power, then your alternator might need to be replaced.