How to Troubleshoot Car Battery Posts

The battery in your car is the main component in the starting system. It provides the necessary current to start your engine. But many times we forget to give it adequate attention and fail to maintain the battery posts and cable terminals clean and in good condition. If you have difficulty starting your car engine, corrosion around the posts and cable terminals or a bad connection might be starving the starting motor from the current it needs to do its job.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Clean rags
• Baking soda
• Foam cup
• Wire brush
• Combination wrench set
• Pliers
• Battery post cleaner brush
• Voltmeter

1. Locate the battery. Most of the time you will find it at the front of the engine compartment to the left or right hand side.

2. Thoroughly clean the battery top and sides with a clean rag and leave it free of dirt and moisture. This helps to keep the battery from building up corrosion and makes it easier to inspect the case for possible damage. If necessary, mix 1 tbsp. of baking soda with 8 oz. of water in a small foam cup. Use a small wire brush and the solution to clean the battery case. Use water to rinse off the solution.

3. Inspect the battery posts or side terminals. If you see corrosion (a soft white and light green substance) buildup around the posts and terminals, clean them with the baking soda solution and brush.

4. Detach the battery cables from the battery posts or side terminals starting with the negative terminal. Use a pair of wrenches if the terminals are bolted to the post or attached to a side terminal. Use pliers with spring-type terminals. Be very careful not to damage the posts or side terminals.

5. Clean the battery posts or side terminals and the inside of the terminal clamps using a battery post/cable cleaner brush or an appropriate wire brush. Make sure to clean any trace of corrosion. If necessary, dip the cable clamps in the baking soda solution.

6. Connect the battery cables to the posts or side terminals but do not over tighten the clamp or you may damage the terminal and the post.

7. Check for voltage drop to make sure you have a good connection. Start the engine. With a voltmeter set to milivolts, touch the negative battery post with the meter’s red lead and the battery cable-just before it reaches the clamp-with the meter's black lead. If the voltmeter reads a voltage greater than 0.1 volt, either the terminal needs more cleaning or there is a connection problem between the clamp and the battery cable. Check the positive post reversing the voltmeter leads connections.

Tips & Warnings

• Install a treated felt washer on each battery post underneath the terminals or a layer of petroleum jelly around the battery posts-after connecting the battery terminals-to prevent corrosion buildup.
• The electrolyte inside a car battery contains sulfuric acid which is highly corrosive and may burn your skin and eyes. Always wear goggles and plastic gloves when cleaning or servicing the car battery.
• Car batteries emit hydrogen gas which is highly explosive. When servicing a car battery, stay away from appliances with open flames like dryers and water heaters; do not allow smoking near or around the battery and work in a well ventilated area.
• Do not place tools you are not using near or close to the battery posts to prevent electrical shorts and sparks that may damage engine components, start a fire or cause an explosion.

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