July 21, 2024
This guide provides step-by-step instructions for changing the battery in a key fob. It includes tips on battery maintenance, common mistakes to avoid, and a comparison of different types of batteries.


If you own a car with keyless entry, chances are you have a key fob. These small devices allow you to unlock and start your car without using a key. However, key fob batteries don’t last forever and need to be replaced every few years. This guide is for anyone who wants to change their key fob battery, but isn’t sure how to do it. In this article, we’ll cover everything from obtaining the correct battery to reassembling the key fob.

Step-by-step instructions

Before you start, you’ll need to make sure you have the right battery. Check your key fob’s manual or contact the manufacturer to determine which type of battery you need. Once you have the battery, here are the step-by-step instructions you’ll need to replace it:

  1. Open the key fob: Use a flat-head screwdriver to pry open the key fob. Be careful not to damage any internal components or scuff the plastic housing.
  2. Remove the old battery: Using a small pair of pliers or your fingers, gently remove the old battery from the key fob. Pay attention to which side of the battery is facing up so that you can insert the new battery correctly.
  3. Insert the new battery: Carefully put the new battery in the key fob, making sure to match the ‘+’ and ‘-‘ signs on the battery with their respective markings in the key fob.
  4. Reassemble the key fob: Put the key fob back together by lining up the two halves and pressing down until you hear a click. Make sure the screws are secure.
  5. Test the key fob: Test the key fob by pressing the buttons to ensure it’s working correctly.

Keep in mind that some key fobs may have a slightly different process, so it’s always important to reference your manual or contact the manufacturer for specific instructions.

Explainer format

Here are some common questions people have about key fob batteries:

How do I know when my key fob battery needs to be replaced?

The key fob may begin to work less effectively or become unresponsive. In some cases, the buttons may need to be pressed multiple times, or the range may decrease. If you notice any of these issues, it’s time to replace the battery.

What kinds of batteries can be used in a key fob?

Key fobs typically use coin cell batteries, which are small, circular batteries. The type of coin cell battery required for each key fob can vary depending on the make and model of the car.

What battery types are recommended?

Lithium batteries are often recommended for key fobs because they tend to last longer and perform better in extreme temperatures; however, your user manual may have specific recommendations.

What are some tips to maximize the lifespan of key fob batteries?

Store your key fob in a cool, dry place and away from other electronics. Limit the time you press and hold buttons on the key fob and avoid dropping it or exposing it to moisture.

Video tutorial

For those who prefer visual aids or need a better understanding of the process, we have made a video tutorial that you can follow along with as you change your key fob battery.

Common mistakes to avoid

Here are some common mistakes people make when changing their key fob batteries:

  • Scratching the plastic housing: It’s important to use the right tools when opening the key fob to avoid scratching or damaging the plastic housing.
  • Reversing the polarity: Make sure to insert the battery with the ‘+’ and ‘-‘ in the correct direction. Otherwise, the key fob will not work.
  • Forgetting to test: Always make sure to test the key fob after changing the battery to ensure it’s functioning properly.

What to do if it doesn’t work

If the key fob still doesn’t work after replacing the battery, there may be a deeper issue at play. Here are some common reasons why it may not work and potential solutions:

  • Dead key fob battery: Make sure you inserted the battery correctly or try installing a new battery.
  • Disrupted electronic signal: This may occur if the key fob is exposed to moisture or is dropped. If the former is the case, let the fob dry out. If the latter is the case, consider buying a new key fob.
  • Syncing issue: If you have replaced the battery in your key fob, but it still isn’t working, it might be out of sync with your car. Try resetting the system by inserting the key into the ignition and turning it to the “on” position. Then, quickly press and release the “lock” button on the key fob. Finally, turn the ignition off and remove the key. Test the key fob, and it should be working again.

Comparison of different types of batteries

Here are some of the pros and cons of different types of key fob batteries:

Alkaline batteries

Alkaline batteries are widely available and inexpensive. However, they don’t last as long as lithium batteries, and their performance can decrease quickly in extreme temperatures.

Lithium batteries

Lithium batteries tend to last longer and work better in extreme temperatures, but they are often more expensive than alkaline batteries.

Rechargeable batteries

Rechargeable batteries are a great alternative, especially if you use your key fob frequently, but they can be difficult to find. They also typically have a shorter lifespan than other battery types.

Importance of battery maintenance

Regular maintenance is important to keep your key fob battery running smoothly. Here are some other tips to extend the battery life:

  • Store your key fob in a cool, dry place.
  • Avoid exposing it to moisture.
  • Don’t hold down the buttons for extended periods.


Changing a key fob battery is a simple process that can help keep your keyless entry system functioning properly. Make sure to follow the step-by-step instructions, choose the right type of battery, and maintain your key fob regularly to extend the battery life. If you experience any issues, refer back to this guide or contact the manufacturer for assistance.

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