Find your key fob battery by checking the fob itself or your car manual
The battery size your key fob needs is printed on the fob itself — usually on the back or inside the battery compartment. Open the fob (often by sliding a small lever or prying gently with a coin) and look at the battery that is already there. The code stamped on it — something like CR2032, CR2025, or LR44 — is the exact battery you need to buy.
If you cannot open the fob or the battery is too worn to read, check your car's owner manual. Search the index for "key fob" or "remote battery" and it will list the correct size. You can also call your car dealer's parts department with your vehicle year, make, and model, and they will tell you the battery code in under a minute.
Do not guess. Putting the wrong size battery in a key fob can damage the contacts, drain faster, or not fit at all. The correct battery costs the same as the wrong one, so there is no reason to experiment.
Key Takeaways
- The battery code is stamped directly on the battery inside your fob — open it and read the letters and numbers printed there.
- CR2032, CR2025, CR2016, and LR44 are the most common key fob batteries, and each one is a different thickness.
- Alkaline batteries (marked LR) last shorter than lithium batteries (marked CR), but both types work in most fobs.
- A new battery usually costs between $3 and $8, and you can buy them at drugstores, supermarkets, and online retailers.
The difference between CR and LR batteries
Key fob batteries come in two main types: lithium (marked CR on the battery) and alkaline (marked LR). Lithium batteries last longer — usually two to four years in a key fob — while alkaline batteries last one to two years. Lithium batteries also perform better in cold weather and hold their charge more steadily over time.
Alkaline batteries are cheaper and easier to find in most stores. If your fob works with either type, alkaline is fine if you do not mind replacing it more often. If you want to go longer between replacements, buy lithium. Both types are safe to use in any fob designed to accept them.
Check your owner manual or the fob itself to see if it specifies one type. Most fobs work with either, but some older models are designed for alkaline only. If the manual does not say, lithium is the safer choice because it works in any fob that accepts CR batteries.
Common key fob battery sizes and what they fit
CR2032 is the most common key fob battery. It is a flat coin-shaped battery about the size of a dime, but thicker. It fits most modern car key fobs, garage door remotes, and small electronics. If you open your fob and see a large flat battery, this is almost certainly what you have.
CR2025 is slightly thinner than the CR2032 but the same width. Some older key fobs and some newer compact remotes use this size. It is not interchangeable with CR2032 — putting a CR2032 in a fob designed for CR2025 can jam the battery compartment.
CR2016 is even thinner and less common. It appears in some slim key fobs and small remote controls. LR44 is a small button battery used in some older remotes and small devices. If your fob uses LR44, the battery compartment is usually very small and round.
When you buy a replacement, match the code exactly. A battery that is too thick will not close the fob. A battery that is too thin may rattle or lose contact with the terminals.
Where to buy key fob batteries and what to expect to pay
Key fob batteries are sold at drugstores (CVS, Walgreens), supermarkets, hardware stores, and online. A single battery usually costs $3 to $8 depending on the brand and whether it is lithium or alkaline. Buying a pack of two or four batteries costs less per battery than buying one.
Name brands like Energizer and Duracell are widely available and reliable. Store brands (CVS brand, Walgreens brand, Amazon Basics) work just as well and cost less. Avoid extremely cheap batteries from unknown sellers online — they may not hold a charge as long.
Some car dealers sell key fob batteries, but they usually charge $10 to $15 for a single battery. You will save money buying at a drugstore or supermarket. If you buy online, order a pack and keep extras on hand — key fob batteries fail without warning, and having a spare means you do not have to rush to a store.
How to replace the battery safely
Open the fob by sliding a small lever on the edge, or by prying gently with a coin along the seam. Do not force it — if it does not budge, look for a hidden slot or button. Once open, note which side of the battery faces up (usually the positive side, marked with a + sign, faces toward you).
Remove the old battery and set it aside. Wipe the inside of the battery compartment with a dry cloth to remove any corrosion or dust. If you see white or green crusty buildup on the contacts, gently scrub it away with a dry cloth or a pencil eraser.
Insert the new battery with the positive side facing the same direction as the old one. Close the fob firmly until you hear or feel a click. Test the fob by pressing each button — the car should lock and unlock, or the garage door should open and close. If nothing happens, open the fob again and check that the battery is seated properly and facing the right direction.
What to do if the fob still does not work after replacing the battery
If you replaced the battery and the fob still does not work, the battery may not be making contact with the terminals. Open the fob again and check that the battery is sitting flat and centered in the compartment. Press down gently on the battery to make sure it is fully seated.
If the battery is seated correctly but the fob still does not work, the problem is likely not the battery. The circuit board inside may be damaged, the buttons may be worn out, or the transmitter may have failed. At this point, you have two options: buy a replacement fob from your car dealer (usually $100 to $300 depending on the car), or buy an aftermarket fob online (usually $20 to $60).
Before you give up, try one more thing: clean the battery contacts inside the fob with a pencil eraser or a dry cloth. Corrosion on the contacts can prevent the battery from making a good connection, even if the battery itself is new.
Frequently Asked Questions
Can I use any CR2032 battery, or does the brand matter?
Any CR2032 battery will work in your fob. Name brands like Energizer and Duracell last slightly longer and cost a bit more. Store brands work just as well. Avoid extremely cheap batteries from unknown online sellers, as they may not hold a charge as long as advertised.
How long does a key fob battery last?
A lithium battery (CR) usually lasts two to four years in a key fob. An alkaline battery (LR) lasts one to two years. The actual lifespan depends on how often you use the fob — a fob you press ten times a day will drain faster than one you press twice a day.
What if I put the battery in backwards?
If you insert the battery with the negative side facing up instead of the positive side, the fob will not work. The fob will not be damaged, but nothing will happen when you press the buttons. straightforward open the fob and flip the battery around.
Can I recharge a key fob battery?
No. Key fob batteries are single-use and cannot be recharged. Once they are dead, you must replace them with a new battery. Do not try to recharge them — they are not designed for it and may leak or fail.
Is it safe to throw away the old battery?
Key fob batteries are safe to throw in the trash in most places. They contain small amounts of lithium or alkaline chemicals, but not enough to require special disposal. If your area has a battery recycling program, you can drop them off there instead, but it is not required.