How to Change a Car Battery

The basic steps to swap out a dead battery for a new one

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The car battery is the thing that makes it all happen in terms of getting a vehicle’s engine running. If you’ve ever sat in a parking lot, listening to the car crank and crank to no avail, you know what happens when the battery is out of the equation. 

Thankfully, dealing with a dead battery isn’t a difficult issue to address. If you can’t recharge the battery you have, the next best (and probably only) thing you can do is swap it out for a new one. The process is simple as long as you take some cautious steps, so here’s all you need to know.

Safety

It’s important to remember that you’re dealing with electricity when working on a car battery. As a result, there are a few important safety steps to take.

  • While not necessary to remove the battery, rubber gloves can add a small degree of safety when dealing with electricity. 
  • Never connect any cables that shouldn’t be connected. That means avoid swapping the wrong battery cables and battery posts or putting the cables anywhere they’re not supposed to go.
  • Be careful when removing the old battery. If it’s damaged and/or leaking, you may want to let a professional do the work instead. 

Things You’ll Need

  • Replacement Battery (and the old one)
  • Safety Wear: Optional but recommended items are glasses and gloves.

Preparation

You can change a battery almost anywhere, but there are a few ideal spots and preparation steps that can make the process easier.

  • Find the right spot. You may not have this luxury if your car is dead on the side of the road. A garage is ideal, but any flat and semi-secluded spot will do.
  • Secure the car. Stop the car and keep the parking brake on. 
  • Find the battery. You may have to consult the owner’s manual if it’s not in a visible or obvious spot under the hood.

How to Replace a Battery

Removing the old battery and replacing it with a new one is a fairly straightforward process. It doesn’t require much in terms of special tools, and the process can go quickly if you’ve taken the basic preparation steps ahead of time. 

Remove the Old Battery

If the battery is completely dead, the first step is to actually remove it from the car. 

  • Remove the negative cable from the negative terminal. The terminal will have a minus sign.
    • Depending on the design of the battery, you may need a wrench to loosen the cable-free.
    • Make sure you actually remove the negative cable. Removing the positive cable first can lead to a short circuit.
  • Remove the positive cable from the positive terminal. The terminal will have a plus sign.
    • If you are using a tool like a wrench, make sure the metal doesn’t contact the terminal.
  • Loosen the battery. There may be some kind of battery hold-down, connectors, and/or fasteners that secure the battery in place. Remove or loosen these until the battery can move freely.
  • Lift the battery out. The weight of the battery may be over 50 pounds, so get some help if necessary. Put the battery to the side in a safe spot.

Add the New Battery

With an empty battery compartment, it’s time to add in the new, fresh car battery. This process is essentially just a reversal of the steps to remove the old battery. 

  • Clean the clamps. Before you actually add the battery, try to remove any corrosion, dirt, or debris from the clamps. You can also clean the battery terminals from any build-up issues. A skinny wire brush and some water or baking soda is usually all you need.
  • Put the new battery into the holder. Make sure it is facing the same direction as the old battery.
  • Secure the battery. Refasten any holders and screws to keep the battery from moving around.
  • Reconnect the positive terminal and cable. Be sure to tighten the clampdown.
    • Be careful not to start with the negative terminal.
    • Avoid any contact with metal parts.
  • Reconnect the negative terminal and cable. Be sure to tighten the clamp. 
  • Test the car. You can try to crank up the engine or just turn on the electronics. If everything powers up, the battery is properly installed and you’re ready to get going.

Tips

  • Inspect the battery every now and then to assess its condition.
  • Most car batteries need to be recharged or replaced after around five years of use. 
  • Make sure you get the right battery for your vehicle. Consult the owner’s manual for detailed information.
  • Keep the batteries in an upright position to avoid leaking any electrolyte solution.

FAQ

Q: Is there any danger to changing a car battery?

A: There can be some inherent risk to changing a car battery. Cracks and corrosion from the old battery can cause some dangerous battery acid leakage. The battery can also still produce a charge, even when the car is off, so you have to keep in mind that you’re working with electricity. 

Q: How do I know which side to remove or connect first?

A: It’s always the opposite side when removing vs. adding cables. The negative side always gets removed first. The positive always gets connected first.

Q: Do I have to replace the old battery?

A: You can often recharge an old car battery before it needs to be replaced completely. To do so, you’ll need a charger, and the battery needs to be able to hold a charge. 

Q: Will changing the battery affect the on-board computers?

A: It shouldn’t, but some computers may experience a reset or memory loss. Damage can occur if disconnecting the battery produces a high-voltage energy spike.