How to Reconnect Car Battery Terminals

by Contributor

The terminals on your car battery are an essential component for the function and life of your engine. Ensuring the battery terminals are connected properly will help your engine run more efficiently and extend the life of the battery. These steps explain how to reconnect car battery terminals.

Step 1

Check that the keys are out of the ignition and the ignition is not in the start position. Wear gloves, as this will not only protect your hands, but will also keep the oils on your hands from getting on the battery terminals.

Step 2

Clean both terminals with WD-40 and a wire brush to remove any corrosion. Wipe with a clean rag to remove excess WD-40 and loose corrosion. Change your gloves, as they may loose corrosion residue on them.

Step 3

Attach the positive terminal first as indicated by a plus sign or an "x." Use a wrench to tighten the bolt on the side of the terminal. Be careful not to tighten too much. Tighten until the wrench can't turn any more, but no further. The lead on the terminal is soft and could break.

Repeat Step 3 for the negative terminal. Once secure, put the key in the ignition and turn it. If it doesn't start, you will need to continue troubleshooting or check your work.


  • Car batteries produce hydrogen gas, so keep open flames and lighted cigarettes away from the engine and battery at all times.
  • Always hook the negative terminal up last, or the battery could be shorted by the tool being used to tighten it.

Items you will need

  • Latex gloves
  • WD-40
  • Wire brush
  • Wrench

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