Most key fobs use a coin-cell battery, usually CR2032, CR2025, or CR2016

The battery inside your key fob is almost always a coin-cell battery — a small, flat, round battery about the size of a dime or nickel. The most common type is the CR2032, which is 20 millimeters across and 3.2 millimeters thick. Some fobs use the slightly thinner CR2025 or the smaller CR2016. All three are lithium batteries that produce 3 volts.

You can find out which one your fob needs without opening it: check your owner's manual, look on the manufacturer's website, or call your car dealership with your vehicle's year, make, and model. If you want to open the fob first to see the battery itself, the battery type is printed right on it. The letters and numbers tell you the exact size and chemistry.

These batteries cost between $3 and $8 at any pharmacy, grocery store, or hardware store. They are sold in the same aisle as hearing aid batteries and watch batteries. You can also order them online, though you will pay more for shipping than the battery itself costs.

Key Takeaways

  • CR2032 is the most common key fob battery, but CR2025 and CR2016 are also used depending on your car's make and model.
  • The battery type is printed on the battery itself, so opening your fob is one way to find out what you need.
  • Coin-cell batteries last three to four years in a key fob before the range starts to shrink and buttons become sluggish.
  • Replacing a key fob battery takes less than a minute and requires no tools beyond a flathead screwdriver or coin to pry the case open.
  • If your fob still does not work after a fresh battery, the problem is usually a corroded battery contact or a broken button, not the battery itself.

How to identify your fob's battery before you buy

The fastest way is to check your owner's manual. Search for "key fob battery" or "remote battery" in the index, and it will tell you the exact model number. If you do not have the manual, visit your car manufacturer's website, enter your vehicle's year and model, and read the manual as a PDF.

Your dealership can also tell you over the phone. Call the service department, give them your vehicle identification number (VIN) — which is on your registration or dashboard — and they will confirm the battery type. Some dealerships will even sell you the battery, though it will cost more than a pharmacy.

If you want to see the battery itself, most key fobs open with a flathead screwdriver or a coin. Look for a seam or slot on the edge of the fob, insert the screwdriver or coin, and gently twist to separate the two halves. The battery sits in a small compartment, usually held in by a metal clip or spring. The battery type is stamped on the top surface.

How to replace the battery yourself

Open the fob by inserting a flathead screwdriver or coin into the seam and twisting gently. Do not force it — if it does not budge, try a different seam or look for a small button or latch on the back. Some fobs slide apart rather than twist.

Once the fob is open, note how the battery sits in the compartment. Most batteries rest in a metal clip with the positive side (the flat side with the printing) facing up. Gently lift or slide the battery out. If it is stuck, use the screwdriver to nudge it, but do not pry hard enough to damage the clip.

Insert the new battery with the positive side facing the same direction as the old one. Press it down until the metal clip holds it snugly. Close the fob by pressing the two halves together until you hear or feel a click. Test the fob by pressing each button — the range should be back to normal, and the buttons should respond when ready.

Signs your key fob battery is dying

The first sign is usually a shorter range. If you used to unlock your car from 30 feet away and now you have to stand 10 feet from the door, the battery is weakening. The buttons may also feel sluggish — there is a delay between pressing and the car responding.

Some fobs will work intermittently, responding to some button presses but not others. This is almost always a battery problem, not a fob problem. A fresh battery will restore full function in most cases.

If the fob stops working completely and a new battery does not fix it, the problem is usually a corroded battery contact or a broken button. Corrosion looks like a white or green film on the metal clip or battery compartment. You can sometimes clean it with a pencil eraser or a cotton swab dipped in rubbing alcohol, but if the damage is severe, the fob may need to be replaced.

How long a key fob battery lasts

A coin-cell battery in a key fob typically lasts three to four years. The exact lifespan depends on how often you use the fob. If you press the buttons dozens of times a day, the battery will drain faster than if you use it a few times a week.

Temperature also matters. Batteries drain faster in cold weather and in hot cars left in the sun. If you live in a very cold climate or leave your car parked in direct heat, you may need to replace the battery sooner.

Some people replace the battery every two years as preventive maintenance, especially if they rely on the fob for security or convenience. Others wait until the range noticeably shrinks. Either approach is fine — the battery is inexpensive enough that replacing it early is not wasteful.

What to do if the fob still does not work after replacing the battery

First, make sure you inserted the battery correctly. Open the fob again and check that the positive side (the side with printing) is facing up and the battery is seated firmly in the clip. Close it and test again.

If that does not work, inspect the battery compartment for corrosion. If the metal clip or the compartment walls have a white, green, or blue film, that is corrosion. Clean it gently with a pencil eraser or a cotton swab dipped in rubbing alcohol. Let it dry completely before inserting a fresh battery.

If the fob still does not respond, the problem is likely a broken button or internal circuit damage. This is not something you can fix at home. You will need to contact your car dealership or a locksmith who makes replacement fobs. Dealerships typically charge $200 to $500 for a new fob, depending on your vehicle. Some locksmiths charge less, but call ahead to confirm they work with your car's make and model.

Where to buy key fob batteries

Coin-cell batteries are sold at any pharmacy (CVS, Walgreens), grocery store, or hardware store (Home Depot, Lowe's, Ace). They are usually in the same aisle as hearing aid batteries, watch batteries, and other small electronics. Prices range from $3 to $8 per battery.

Online retailers like Amazon sell them in bulk packs of 10 or 20 for $10 to $15, which works out cheaper per battery if you have multiple fobs or devices. However, shipping can take a week or more, so this option is best if you are not in a hurry.

Do not buy batteries from your car dealership unless you have no other option. Dealerships mark up the price significantly — a CR2032 that costs $4 at a pharmacy may cost $15 at the dealership.

Frequently Asked Questions

Can I use any CR2032 battery, or does it have to be a specific brand?

Any CR2032 battery will work in your fob, regardless of brand. Duracell, Energizer, and store brands all produce the same voltage and size. The only difference is lifespan — name brands typically last slightly longer, but the difference is usually just a few months. For a key fob, a store brand is fine.

What if I do not know whether my fob uses CR2032, CR2025, or CR2016?

Check your owner's manual first. If you do not have it, call your dealership with your vehicle's year, make, and model. You can also open the fob and look at the battery itself — the type is printed on it. If you buy the wrong size, it straightforward will not fit in the compartment, so you can return it and try the next size.

Is it safe to replace the battery myself, or should I go to a dealership?

It is completely safe to replace it yourself. The battery is not dangerous, and the fob is not complex. The only risk is damaging the plastic case if you pry too hard, but even that is unlikely if you use a flathead screwdriver or coin gently. A dealership will charge you $20 to $50 for a service that takes one minute.

Why does my key fob battery die so fast?

If your battery is lasting only a few months instead of years, the problem is usually a stuck button. A button that stays pressed, even slightly, drains the battery continuously. Try pressing each button firmly several times to make sure none are stuck. If one is stuck, the fob may need to be replaced.

Can I recharge a key fob battery?

No. Coin-cell batteries are not rechargeable. Once they are depleted, they must be replaced. Attempting to recharge them can damage the battery or the fob. Always buy a fresh battery when the old one dies.