How to Disconnect a Car Battery Safely

how to disconnect a car battery

Since car batteries don’t last forever, there will come a time when your batteries need to be replaced. But before installing your new battery, you need to remove the old one first. Knowing how to disconnect a car battery safely is crucial to avoid mistakes that might harm you or damage your battery permanently. 

Disconnecting your car battery is a relatively simple process, but there’s a specific order that should be followed. If you haven’t tried taking out car battery before, you’ll learn how in this article. Follow the six simple instructions below to safely remove car battery and save a few bucks.

Situation When You Need to Disconnect a Car Battery

When do you need to disconnect a battery? Your car won’t start without a battery, but you may need to remove the existing one for the following reasons:

  • Vehicle maintenance – Sometimes taking out a car battery is required during vehicle maintenance to prevent the risk of electrical issues or cause any harm to yourself. 
  • Battery replacement – Batteries need to be replaced every 3-5 years and removing them would be mandatory. 
  • Battery recharging – When your battery loses power, you may need to disconnect them while charging.
  • Storage – When you’re planning to be away for a long time, it might be a good idea to disconnect your battery to save power. 

Tools You Need to Disconnect a Car Battery

Removing a car battery requires certain equipment as you can’t take them out manually. Most battery cables typically use 10mm nuts, while battery brackets use 10 mm, 12mm, or 13mm bolts, depending on the vehicle. To safely remove car battery, you’ll need these tools:

  • 10 mm open-end wrench
  • 10 mm drive socket wrench (check the owner’s manual for reference)
  • Drive socket extension set 
  • Battery terminal cleaning brush
  • Battery Terminal Dielectric Grease (optional)
  • Anti-rust spray (optional)
  • Gloves 
  • Goggles

How to Disconnect a Car Battery

Now that you have the necessary tools, it’s time to get to work. Here’s how to disconnect car battery safely.

Step 1: Turn off the ignition

The first thing you need to do is turn off the ignition and remove the key. You should never attempt to remove the battery while the engine is running to avoid damaging the alternator. 

Step 2: Put on your safety gear

Safety is of the utmost importance. Car batteries generate powerful electricity that can be dangerous. So if you have any gloves or safety goggles on hand, put them on. 

Step 3: Locate the car battery

Next, locate your car battery. Most of the time, it can be found near the engine bay’s surface. Pop your hood open and you should be able to see your battery attached to two large cables. If it’s not there, try to check the trunk. You can refer to your owner’s manual to be sure. 

Step 4: Locate the car battery’s positive and negative terminals

Once you’ve located the battery, find its positive and negative terminals. The positive terminal is marked with a plus (+) symbol and covered with a red cap, whereas the negative terminal has a minus (-) symbol and a black cap. Then check the terminals for corrosion, damage, or leakage. 

Step 5: Unbolt the cables using the right wrench

If your battery has plastic caps on, remove them first and look for the right wrench that fits the bolts and nuts that secures the cables. There’s no universal size that applies to all terminal hardware, but most cables typically use 10mm nuts and bolts. If it’s not, you’ll need to check it yourself or consult your owner’s manual. 

Here’s how you do it:

  • Use the wrench that fits to loosen the nut holding the cable to the negative terminal first.
  • Remove the negative clamp from the terminal by lifting it free then push it far aside.
  • Disconnect the positive clamp from the terminal the same way and push it far away from the battery. (Important: Make sure not to let your wrench touch both terminals at the same time. This prevents your battery from shorting out or creating sparks.)
  • After removing battery cables, use your battery terminal brush to scrub off the corrosions from the terminals.
  • Make sure to clean the battery post and the inner surface of the cable connectors as well while you’re at it.

Step 6: Remove the battery hold-down clamp

Most batteries are secured with a hold-down clamp on top to hold them in their place. Remove the nuts that hold the clamp in place using a socket wrench. 

Some car models have their battery hold-down clamp or brackets on the side. In this case, you will need a socket extension to remove the bolts as side brackets don’t leave much space to maneuver. Remove the hold-down clamp and pull out the battery.  

These are all the steps for removing your car battery. If you’ve got more questions on this topic, keep reading below. Need help right now? Contact Neighborhood Roadside Assistance for your 24/7 battery replacement needs in New Jersey. 

Frequently Asked Questions

Before you proceed with the actual work, check out these answers to the most common car battery questions.

Can I just disconnect the negative terminal?

No. To take out your battery from your car, you need to disconnect both terminals as they are securely bolted to the battery cables. 

What happens if you remove the positive terminal first?

When you accidentally remove the positive terminal first, it doesn’t automatically mean that something bad will happen as long as you don’t bridge the gap between the positive terminal and any metal surface of the car. Doing so will create a short that might cause fuses to pop or the battery could explode. 

Should you disconnect the battery when not in use?

Leaving the battery connected to your car when not in use for a long time will drain your battery. So, if you’re planning to go on vacation and leave your car unattended, it’s best to disconnect vehicle battery to save power. 

How do I temporarily disconnect my car battery?

Remove the battery cables from the terminal while leaving the battery in place. There’s no need to remove the bracket or take out the battery itself.