How to Check Battery Voltage

Whether it's the battery in your car or one you just pulled out of the junk drawer, sometimes you need a quick, reliable way to assess a battery's health. A digital multimeter is an inexpensive, easy-to-use tool with a variety of purposes, including testing batteries. With an inexpensive digital multimeter, you'll be able to evaluate a battery before relying on it to power your equipment.

• 1

  Inspect the battery to be tested for signs of corrosion or damage. Replace damaged, swollen, or badly-corroded batteries as any test results will be unreliable.

• 2

  Disconnect the battery from any charging system by removing the negative lead and then the positive lead from the battery using an open-ended or adjustable wrench if necessary. Clean the battery terminals and leads with a wire brush.

• 3

  Read the battery label to determine the operating voltage of the battery and set the digital multimeter to the DC Volt scale closest to and higher than that voltage.

• 4

  Touch the red lead of the digital multimeter to the positive (+) battery terminal and touch the black lead to the negative (-) battery terminal. Read the voltage display on the multimeter to determine if the battery is within 10% of the expected voltage.

• 5

  Discard and replace any non-rechargeable batteries that are 10% or more below the expected voltage. Re-test rechargeable batteries after recharging them for sufficient time to restore full voltage. Discard and replace any rechargeable batteries that fail a second voltage test.