How to Safely Disconnect a Car Battery

If a car battery is working well, we tend to forget it exists. But if it stops working, do you know how to disconnected it and replace it safely? Learn how here.

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Car batteries are an essential part of vehicle operation, and like everything, they stop working after a while. When this happens, knowing how to properly disconnect your car battery is vital. Mistakes could ruin your battery permanently or cause you serious harm. Learn to do things the right way and in the right order, so you can be safe and confident next time you need to disconnect a car battery.

Tools Required

  • Cup style wire cleaning brush
  • Pipe cleaning wire brush
  • Socket wrench set or small adjustable wrench

Materials Required

  • Anti-corrosion grease (optional)
  • Anti-rust spray (optional)
  • Heavy-duty shop towels

Project step-by-step (5)

Step 1

Shut Everything Off and Find the Battery

  • Make sure your vehicle is not running and all electrical components are off before starting the battery disconnection process.
  • Open your vehicle’s hood if that’s where the battery is housed, as it is in most vehicles. If your battery is somewhere else, do whatever you need to do to gain access.
  • Remove the red plastic cover from the battery’s positive terminal.

Find the BatteryRobert Maxwell for Family Handyman

Step 2

Disconnect the Battery Cables

  • Use your socket wrench or adjustable wrench to loosen the nut holding the cable onto the negative battery terminal. The terminals will be marked positive and negative. Make sure you disconnect the negative terminal first.
  • Lay the disconnected negative cable carefully to one side, making sure it’s well away from the battery terminal.
  • Disconnect the cable from the positive battery terminal in the same way, then lay it to one side.
    • While loosening the cables, be sure not to touch your wrench to both terminals at the same time, because this will allow electricity from the battery to flow through your wrench.

Disconnect the Battery CablesRobert Maxwell for Family Handyman