Test Auto Alternator Output

A voltmeter or multimeter is a expedient object when testing your vehicle's alternator output.

The alternator in your automobile or Motor lorry is a critical Element of the vehicle's charging operation. Without it, your battery Testament die and you'll bargain yourself in itch of fixed jump-starting or towing. Happily, there is a lucid analysis you can perform in line to assess the alternator and glare provided it's producing the Correct voltage output. All that's required is an inexpensive digital voltmeter or multimeter, which you can invest in at most any automotive function store.


1. Turn off the automobile’s ignition switch and Proceeds the hood. Treasure trove the battery within the engine compartment, then remove any plastic shields covering the battery. Many guards or shields Testament simply unhook or unclip. Some, but, Testament lack you to loosen and remove screws or bolts. Since circumstances, you Testament desideratum the proper screwdriver or wrenches.

2. Check to ensure your voltmeter is adjusted for the DC (direct current) scale and, if it is a multimeter, that it’s set for measuring voltage. Connect the voltmeter’s negative clip to the battery’s negative terminal. The color black and the minus sign ( - ) are associated with the negative clip and/or terminal.4. Note the number indicated on the voltmeter or multimeter display.

Then connect the positive clip on the voltmeter to the positive battery terminal. You can discern which clip and/or terminal are positive by looking for a plus sign ( + ) and the color red.3.

This is the base voltage for your battery. It should read somewhere between 12.5 and 12.8 volts.

5. Tell your helper to begin the automobile and rev the engine to approximately 2,000 rpm.

6. Stare at the display on your meter once again. You should see a reading of approximately 13.5 to 14.4 volts. This shows the amount of voltage produced by the alternator. If you see a reading of less than 13.5 volts, the alternator’s output is too low, which may result in a drained battery. You may need to replace your alternator.