How to determine if a maintenance free car battery is bad

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How to determine if a maintenance free car battery is bad
(dead battery image by Katrina Miller from

What does “maintenance free” mean on your car battery? Does it mean that you have to discard it if it goes dead? No. It simply means that you do not need to add water to it on a regular basis. The batteries of only 20 years ago required water to be added on a regular basis. If you have a problem with your maintenance-free battery, it can be tested to determine if it can be reconditioned or replaced. This testing requires some basic electrical tools as well as common household tools and can be done at home.

Skill level:

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Things you need

  • Protective eye wear
  • Rubber gloves
  • Wrench
  • Battery post/terminal cleaner
  • Voltmeter
  • Battery load tester
  • Work bench

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  1. 1

    Open the hood of the car and remove the battery cables with a wrench. Remove the positive (+) red cable first then the negative (-) black cable. Lift the battery out of its tray and place it on a work bench.

  2. 2

    Put on safety glasses and rubber gloves. Clean the battery posts by placing a battery post cleaner on each battery post then twisting it back and forth until the posts are clean and bright.

  3. 3

    Connect a load tester to the battery's positive terminal first then to the negative post. The positive post is the larger of the two and will be marked with a plus (+). Connecting the positive terminal first will prevent sparking. Switch the load tester to “TEST” and check to see that the arrow on the meter does not drop below 12 volts. If it does or if it drops to the bottom of the scale and fails to come back up, the battery cannot be saved and must be replaced. If it reads 12 volts, it can be reconditioned.

Tips and warnings

  • Connecting and disconnecting the positive battery cable will eliminate dangerous sparks.
  • Never set a battery on a cement floor. This will ruin the battery. if you need to set it on a floor, place a wood block beneath it.

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