How To Charge A Car Battery

Dustin Hawley | Mar 24, 2021

Sooner or later, most drivers encounter the inevitable inconvenience of a dead car battery. You don’t need to be an expert auto mechanic to know that without a running battery, your car won’t start at all. You’ll have to call a roadside maintenance service or find a way to get your vehicle to a repair shop in this situation. Both of these options are less than ideal.

How to charge a car battery

Alternatively, you have the option of avoiding these choices and charging your car battery yourself. So long as you have the proper equipment, like a portable battery charger, you can perform this task anywhere you need to, even when you’re stranded on the side of the road. 

Let’s break down how to charge a car battery.

Prepare The Battery

Before you start charging the battery, you’ll need first to prepare it. To do so, start by determining whether you need to remove your battery from your car to perform the charge. Some car batteries must be lifted out of their holding trays, while others can be charged as they are. In most conventional vehicles, you will likely not have to remove the battery to charge it.

In the unique situation where you need to remove your battery to charge it, do so first before you start the charging process.

Turn Off All Car Electronics

Once your battery is prepared for charging (if necessary), make sure that all electronics in your car are powered down, including any accessories such as the interior cabin light or the stereo. If any electronics remain powered on during charging, the battery may experience an electrical arc during the process. Again, make sure all power and electronics have been turned off!

Remove The Negative/Ground Cable, Then Positive

Having confirmed that all power is off, you can begin to remove the negative or ground cable for your car’s battery. It’s almost always a black cable marked with a “-“ symbol. The positive cable will be red and display a “+” symbol. 

Your battery may also have plastic caps over its terminals that must be pried free for you to remove the cables. If these caps are present, remove them if necessary to access the terminals.

Use a socket wrench to loosen the negative cable, then carefully pull it away from the battery. Ensure that the negative cable is situated far from the positive cable to prevent a charge from transferring between the two sources. 

You’ll need to repeat the removal process for the positive cable and terminal. Move the positive cable away from the negative terminal for the same reasons described above.

Clean The Battery Terminals

Before you start charging your battery, it’s a good idea to clean your terminals. You can do so using a terminal cleaning brush, which looks similar to a small toothbrush and is used to clear away corrosive debris and dirt from the terminals. You can also use either a commercial battery cleaning solution or make your own by mixing baking soda and water.

Cleaning the terminals neutralizes battery acid and prevents malfunctions from occurring when you charge the battery and reconnect the terminals. 

When cleaning your battery’s terminals, always make sure you wear face and eye protection for safety.

Connect The Battery Charger

With the steps mentioned above now complete, you are ready to hook up your battery charger. 

Before beginning any of the processes noted below, please note that your charger may have specific instructions for its operation. You should follow these if they contradict our guidelines below.

Here is how you need to connect your battery charger.

  • First and foremost, ensure that the charger is powered off before beginning use.
  • Next, hook the positive cable on the charging unit up to the corresponding positive terminal on your battery.
  • Repeat the process by hooking up the negative cable to the negative terminal on your battery afterward. Do not reverse these steps – the positive cable must be connected first.
  • With both cables connected in the correct order, turn your charger on. Begin by setting it to the lowest rate by default, especially if you are using the charger for the first time
  • If your charger has a timer, set it for the appropriate charge time. This timer will charge your battery for a set time. If you don’t know how much time you need to charge your car’s battery, consult your owner’s manual or an online search.

Remove The Charger Once Charging Is Complete

After your charger has run for its desired duration and the charging process is complete, you can remove the charger’s connecting cables from your car battery. In some instances, the charger may have a meter or indicator telling you when it is safe to do so.

To safely remove the charger, make sure to power if off before touching any of the other controls on the unit. Only after the charger has been shut off is it safe to remove the cables. Once powered down, remove the positive cable first, followed by the negative.

After removing the cables, don’t forget to replace the cables on the terminals for your car battery. Again, make sure you reconnect the positive cable before replacing the negative, and be sure to use your wrenches to screw on any nuts or bolts as needed. If you removed the car charger entirely, you will need to set it back into its tray and replace the hold-down clamp. 

Once reconnected, you are finished. That’s all there is to it! 

Summary

Now that we have outlined the process and you’ve seen it for yourself, it should be relatively clear that charging a car battery isn’t an overly complicated task. As long as you are sure to handle the cables in the correct order and you use the proper charging equipment, your battery should be charged up in no time.

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