How To Safely Disconnect A Car Battery

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A step-by-step guide to disconnecting and removing your car battery

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The battery in your car is a vital component that provides power to start your vehicle as well as keep various electronic systems running. In some situations, you may find you need to disconnect the battery and even remove it entirely. Here's a handy guide to why and how to safely disconnect and remove your car battery.

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Reasons For Taking Out Your Car Battery

Taking out your car battery can be a smart move in certain situations, but for the most part, simply disconnecting it should serve the purpose of preventing it from being drained while you're not driving the car.

The basic premise is that if you aren't driving your vehicle, the battery doesn't charge up again although certain electrical systems like the clock and on-board computer continue to use power from the battery to run. Over time, this will drain the battery if it's not started up and run every now and then. Some reasons why you may consider disconnecting and/or removing your car battery include:

  • Vacation or long-term storage: If you're going away on vacation for a few weeks and there won't be anyone to drive the car, you should disconnect the battery. The same applies if you are putting your car in storage. Read our guide on secure car storage here.
  • Work is being done: Whether it's mechanical work or bodywork repairs that need to be done, or in the wake of an accident while paperwork is being processed, if the process means the car won't be driven and it will be left standing for some time, it's best to disconnect the battery. Obviously, if mechanical work requires electrical systems to be operational, you wouldn't disconnect the battery and the car would probably be regularly started regardless.
  • Showpieces: Cars that are on display and will be left standing for long periods of time without being driven will also see batteries run down over time.

Before You Disconnect Your Car Battery…

If any of the above scenarios apply to you and you need to disconnect the battery, there are a few things to prepare before jumping right in and pulling wires. So, before we give you a step-by-step guide, note the following:

  • Know that when you disconnect your car battery, the electronic systems may reset to factory defaults - this includes clocks and radios that will require you to manually configure them again.
  • Check the lifespan and condition of the battery with special attention given to areas that show wear, corrosion, or leaks. All batteries have a finite lifespan, so knowing how long your car battery lasts is important. In cases of severe corrosion or leaks, it is best to find a professional to assist.
  • Have the right tools on hand - while disconnecting is easier than removing the battery, you'll still need to have some equipment on hand. It's best not to start the process if you cannot complete it due to not having the correct gloves, goggles, or socket for your wrench. Some modern cars have the cables attached to the bracket or post, which may require a special battery removal tool. In such cases, you'll need to source one from your local auto-parts shop or dealership.
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How to Disconnect and Remove Your Car Battery

With all the preparations made, here are the important steps for how to disconnect and remove a car battery:

  1. Ensure the vehicle is turned off and you are wearing safety gear. Never try to disconnect or take out the battery with the car running or even with the ignition switch turned to power the accessories.
  2. Open the hood, locate the battery, and identify the terminals: Usually, battery terminals are identified by color - red is positive, black is negative. You may find a plus or minus sign located near each terminal, too. (Note that some cars have the battery located in the trunk). These may be covered in a color-coded plastic cap - flip the cap open to reveal the connector. There will be a cable running from each connector point.
  3. Choose the right socket size to loosen the nut on the connector. Starting with the negative terminal, use a wrench to loosen the nut by turning it counter-clockwise. Once it is loose enough, you should be able to lift it or pull it off the battery. Make sure you pull it away from the battery - the cable must not come into contact with the battery again until you're ready to reconnect. You may need to use a special tool if your car has these cables attached to the post.
  4. Loosen the nut on the positive terminal and unhook the connector, being careful not to let it touch any metal parts of the car or the battery. The battery is now completely disconnected.
  5. If you need to remove the battery entirely, you may need to loosen any brackets or clamps that hold it in place. Use the correct socket to remove the nuts and then lift the battery out and away. Be careful, though, car batteries are often heavier than you think!

If you're replacing the battery with a new one, or you are ready to reconnect the car battery again, this is the proper way to go about it - as in the above step 1, ensure the car is powered down.

  1. Install the battery into the mounting bracket, ensuring you don't make any connections between the cables and the battery. Secure with required bolts and nuts.
  2. Starting with the positive terminal, connect the cable to the terminal and fasten the nut.
  3. Connect the cables to the negative terminal, and secure the nut.
  4. Check that both terminals are properly secure, and close the covering caps, if applicable.
  5. Check to see if your vehicle starts.
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Conclusion

Whatever reason you may have for wanting to unplug or remove your car battery, you should only ever attempt to do so if the vehicle is turned off and the battery is not leaking or severely corroded. Remember to wear safety gear before the removal of your car battery, and follow the negative-first rule when you disconnect the battery cables. The opposite is true when you want to reconnect, starting with the positive terminal first.

FAQs

If I disconnect my car battery, will it stay charged?

If you disconnect or take out your car battery and store it, it will not run down - technically. Although batteries do have a self-discharge rate, it is much, much slower when it's not being drained by anything. A fully charged battery unit can hold its charge for a couple of months when disconnected and stored appropriately.

Which car battery terminal should I disconnect first?

Regardless of whether you're disconnecting the battery of your tiny Chevrolet Spark or your giant SUV, the rule is the same. For disconnecting, start with negative (marked black or identified by a minus sign).

Is it okay to touch car battery terminals?

You can technically touch car battery terminals with your hands without fear of electrocution, but it's still not a good idea to go about testing the theory. There are bigger risks, though, which include touching the terminals with a metal wrench, for example, which would create a spark, ignite the gas in the battery, and result in an explosion.

If my car won’t start, does it mean the battery is dead?

There are many possible causes for why your car won't start. If your brand-new truck isn't starting, it's unlikely that it's a battery problem as that should be fresh and working fine. However, if your older Ford Ecosport is not starting but you hear a clicking sound or have a slow crank when you turn the key, it's probably a flat battery. Warning signs to look out for include dim headlights or needing to push the gas pedal to get it to start. Here are some tips on how to keep your car battery from dying in cold weather.

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