What kind of battery is a car key battery?

Most car key fobs are powered by a small 3-volt lithium coin cell, with CR2032 being the default. Some designs use CR2025, CR1632, CR2016, or, in older or smaller remotes, the 12-volt A23 battery.

The exact type depends on your make and model; to be sure, check the battery code on the current battery, consult your owner's manual, or contact the dealer. This article explains the common types and how to replace them safely.

Common battery types used in car key fobs

Below are the batteries you’re likely to encounter across different makes and models. Each entry notes the typical voltage and when it’s commonly used.

• CR2032 — 3V lithium coin cell; the most widely used size for modern key fobs.


• CR2025 — 3V lithium coin cell; thinner than CR2032 and used in slimmer fobs or compact remotes.


• CR1632 — 3V lithium coin cell; used in some compact or alternative-design remotes.


• CR2016 — 3V lithium coin cell; found in smaller or older fobs.


• A23 (also called 23A) — 12V battery in a small rectangular form; used in certain older or specific vehicle remotes.

When in doubt, always verify the exact battery type by inspecting the current battery's code or consulting the vehicle manual. Using the wrong size or voltage can prevent the fob from functioning properly.

Replacing the battery: step-by-step guide

Before attempting a replacement, understand that the exact procedure can vary by model. The steps below cover the typical process for most fobs that use a 3V coin cell.

1. Confirm the correct battery type by inspecting the existing battery or checking the manual.


2. Purchase the replacement battery of the same type and voltage (e.g., CR2032 for many modern fobs).


3. Prepare a clean workspace and a small, non-metallic tool or plastic pry tool to avoid damaging the key fob.


4. Open the fob case carefully, using the seam or a designated opening point; do not force the shell apart.


5. Remove the old battery, noting its orientation (which side is facing up).


6. Inspect the battery contacts for corrosion or debris and clean gently if needed with a dry cloth.


7. Insert the new battery in the same orientation as the old one, ensuring it sits securely and contacts are solid.


8. Reassemble the fob casing and press the buttons to verify basic function; if available, test the lock/unlock functions from a distance.


9. If the fob still doesn’t work, you may need to re-pair or re-sync it with the car according to the manual, or consult the dealer for programming assistance.

Proper disposal of the old battery is important—recycle it at a recycling center or store that accepts spent batteries. If you’re unsure about the process or your vehicle’s specific fob, contact your dealer or a qualified auto parts retailer for guidance.

Tips and safety for battery care

To prolong life and avoid surprises, keep a spare battery on hand for your most-used fob and store it in a cool, dry place. Avoid exposing the fob to extreme heat or moisture, which can damage circuitry or battery performance. If your fob is behaving erratically even after a new battery, it may be time for a professional check or reprogramming.

Summary

In most cases, a car key fob runs on a 3V lithium coin cell, with CR2032 being the default choice. Other common sizes include CR2025, CR1632, CR2016, and, in some designs, A23. Replacement involves identifying the correct type, opening the fob safely, swapping the battery with correct orientation, and reassembling and testing the device. When in doubt, consult the owner’s manual or your dealer to ensure compatibility and proper re-pairing if required.

What battery do I get for my car key?

Although most automobile keys use CR2032 and CR2025 3-Volt batteries, not all key fobs can accommodate them. Different car remote controls require various batteries. The owner's manual will list the precise type. If you don't have access to the owner's manual, you may always check your current key fob.

Can you use a CR2032 instead of CR2016 for key fob?

No, you cannot use a CR2032 instead of a CR2016 because a CR2032 is significantly thicker and will likely not fit in the key fob. While both are 3V batteries, the CR2032 is 3.2mm thick, whereas the CR2016 is only 1.6mm thick, making it too bulky to fit in the slot designed for the thinner battery. 
This video demonstrates how to replace a key fob battery: 49sReviews, Tutorials & TechYouTube · Apr 10, 2024

• Physical fit: The CR2032 is roughly twice as thick as the CR2016 and may not fit into the battery compartment. 
• Voltage: Both batteries provide 3V, so they are electrically interchangeable, but only if the CR2032 can fit in the space provided. 
• Capacity: The CR2032 has a larger capacity, meaning it could last longer if it were the correct size. 
• Correct battery: Always use the battery size recommended by the manufacturer to ensure the fob functions correctly and to avoid damage. 

Can I replace the key fob battery myself?

Yes, you can replace the key fob battery yourself by carefully opening the fob, swapping the old battery for a new one, and snapping it back together. You'll need a small flathead screwdriver and the correct replacement battery, which is often a CR2032 or CR2025, to complete the task. 
This video demonstrates how to replace a key fob battery: 59sSchaller HondaYouTube · May 3, 2023
Step-by-step guide to replacing your key fob battery

1. Open the key fob: Look for a small slot or seam on the edges of the fob. Use a small flathead screwdriver to gently pry the two halves apart. Some fobs have a release button for a hidden physical key that can be used to help pry it open. 
2. Remove the old battery: Carefully lift the old battery out of its compartment. Note the correct orientation (positive + side facing up) before removing it. 
3. Install the new battery: Place the new battery into the fob, ensuring the positive + side is facing the correct direction, and press it into place securely. 
4. Reassemble the fob: Align the two halves of the fob and press them together firmly until they snap into place. If there's a key insert, slide it back in. 
5. Test the fob: Press the buttons on your fob to ensure it's working properly, like locking or unlocking your car. 

Important tips

• Identify the correct battery: Check the code on the old battery, such as CR2032 or CR2025, to make sure you buy the right replacement. 
• Be gentle: Be careful not to use too much force when prying the fob open to avoid breaking the plastic. 
• Reprogramming: In most cases, a key fob does not need to be reprogrammed after a battery change, but if it's not working, you may need to have it reprogrammed by a professional. 

What to do if car key battery is low?

If your car key fob battery is low, you can replace it yourself by opening the fob and swapping the old battery for a new one, or you can have a local auto parts store or dealership do it for you. As a temporary measure, you can often still use the fob to start the car by holding it directly against the push-to-start button or inserting it into a backup slot, while the mechanical key inside the fob can be used to unlock the car manually. 
Immediate actions

• Use the mechanical key: Most key fobs have a physical key hidden inside. Look for a small button or lever on the fob to release it, then find the physical keyhole on the driver's door handle to unlock the car. 
• Start the car with the dead fob: 
  • Push-button start: Place the dead fob against the start button and press it to start the car, as the car can still detect the fob's signal when it's in close proximity. 
  • Backup slot: Some vehicles have a specific slot in the dashboard or center console to insert the fob to start the car. Check your owner's manual to see if your car has this feature. 

This video demonstrates how to find the mechanical key and the backup slot to start the car: 1mTech Device NewsYouTube · Apr 11, 2019
Long-term solution: Replace the battery 

1. Get the correct battery: Check your old battery or owner's manual for the correct type. Common types are CR2032, CR2025, and CR2016. 
2. Open the fob: Gently pry the two halves of the fob apart. Your owner's manual may have specific instructions, but you can often use a small flathead screwdriver or a coin to carefully open it. 
3. Replace the battery: Remove the old battery and insert the new one, making sure the positive (+) side is facing the correct direction. 
4. Close the fob: Snap the two halves of the fob back together. You may be able to do this at home or take it to a professional. 

This video shows how to open the key fob and replace the battery: 47sEveryman DriverYouTube · Dec 20, 2020