Most key fobs use coin-cell batteries, usually CR2032 or CR2025
The battery in your key fob is almost certainly a coin-cell battery — a small, flat, round battery about the size of a dime. The most common type is the CR2032, which is 20 millimeters across and 3.2 millimeters thick. Some fobs use the slightly thinner CR2025 (20 mm across, 2.5 mm thick) or the smaller CR2016. A few older or larger fobs may use CR2477 batteries, which are thicker and hold more charge.
You can find the exact battery your fob needs printed on the back of the fob itself, or in your vehicle's owner's manual. If neither source is available, a battery retailer or your car dealer can identify it by the fob model. The battery typically lasts three to four years with normal use, though heavy use — pressing the button dozens of times daily — can shorten that to two years.
Key Takeaways
- CR2032 is the most common key fob battery, and you can find the exact type printed on the back of your fob or in your owner's manual.
- Coin-cell batteries cost between $3 and $8 at pharmacies, grocery stores, hardware stores, and online retailers.
- Most key fobs are designed so you can open them with a coin or flathead screwdriver and swap the battery yourself in under a minute.
- If your fob stops working after a new battery, the problem is usually a corroded battery contact or a worn button pad, not the battery itself.
How to identify your fob's battery type
The quickest way is to look at the back of your key fob. Most manufacturers print the battery type directly on the plastic — you will see something like "CR2032" or "CR2025" stamped or printed there. If the printing has worn away or is not visible, check your vehicle's owner's manual in the section on key fob maintenance or battery replacement.
If you do not have the manual, call your car dealer with your vehicle's year, make, and model. They can tell you the battery type in one call. You can also take the fob to any pharmacy, grocery store, or battery retailer — they can open it and identify the battery by sight.
Where to buy key fob batteries
Coin-cell batteries are sold almost everywhere. You will find them at pharmacies (CVS, Walgreens), grocery stores, hardware stores (Home Depot, Lowe's), big-box retailers (Target, Walmart), and online (Amazon, eBay). A single CR2032 typically costs $3 to $8 depending on the brand and where you buy it. Name brands like Energizer and Duracell cost more than store brands, but all coin-cell batteries of the same type perform similarly.
Buy one extra battery while you are at it. Key fob batteries fail without warning, and having a spare means you can replace it when ready rather than making a second trip to the store.
How to replace the battery yourself
Most key fobs are designed to open without tools, though some require a coin or flathead screwdriver. Look for a small slot or seam on the edge of the fob — this is where the two halves separate. Insert a coin or screwdriver into the slot and gently twist or pry until the fob cracks open. Do not force it; if it does not move, try a different spot on the seam.
Once the fob is open, note which side of the battery is facing up — this matters. Remove the old battery by gently prying it out with your fingernail or the edge of the coin. Slide the new battery in with the same side facing up as the old one was. Close the fob by pressing the two halves together until they click. Test the buttons to make sure it works before you put it away.
The entire process usually takes less than a minute. If the fob still does not work after you install a new battery, see the troubleshooting section below.
Why your fob might not work even with a new battery
If you replaced the battery and the fob still does not respond, the problem is usually not the battery itself. The most common culprit is corroded battery contacts — the small metal springs or clips inside the fob that touch the battery. If they are green, white, or black, they are corroded and need cleaning.
Open the fob again and look at the metal contacts. If they are discolored, rub them gently with a pencil eraser or a small piece of fine sandpaper until they are shiny again. Reinstall the battery and test. If that does not work, the problem may be a worn rubber button pad inside the fob — the part that conducts electricity when you press a button. This cannot be fixed at home and requires a replacement fob or a visit to a dealer.
Coin-cell battery types and what they fit
| Battery Type | Size (mm) | Common Uses |
|---|---|---|
| CR2016 | 20 × 1.6 | Small key fobs, watches, calculators |
| CR2025 | 20 × 2.5 | Some key fobs, hearing aids, small electronics |
| CR2032 | 20 × 3.2 | Most car key fobs, garage door openers, scales |
| CR2477 | 24 × 7.7 | Larger key fobs, some remote controls |
How long a key fob battery lasts
A typical key fob battery lasts three to four years with normal use — pressing the button a handful of times per day. If you use your fob heavily (pressing it dozens of times daily, or leaving it in a hot car), the battery may last only two years. Cold temperatures do not significantly shorten battery life, but heat does.
You will notice the fob starting to fail before the battery is completely dead. The button may require a harder press, or it may work only from a shorter distance. When this happens, replace the battery. Do not wait until the fob stops working entirely, because you may be locked out of your car.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
Not safely. CR2032, CR2025, and CR2016 are all 20 millimeters across but different thicknesses. Using the wrong thickness can prevent the fob from closing properly or cause the battery to lose contact. Always use the type printed on your fob.
Is it cheaper to replace the battery myself or go to the dealer?
Replacing it yourself costs $3 to $8 for the battery. A dealer typically charges $50 to $100 for the same job, including labor. If you are comfortable opening the fob, doing it yourself saves money.
What should I do with the old battery?
Coin-cell batteries contain lithium and should not go in the trash. Most pharmacies and retailers that sell batteries accept old ones for recycling at no charge. Some communities also have battery recycling drop-off locations — search your city name plus "battery recycling" to find one nearby.
Will the fob work right away after I put in a new battery?
Yes, coin-cell batteries work when ready. If the fob does not work after you install a new battery, check that the battery is facing the correct direction and that the metal contacts inside are clean and shiny.
Can I buy a universal key fob instead of replacing the battery?
Universal fobs exist and cost $15 to $40, but they require programming to your vehicle, which usually means a trip to the dealer. For most people, replacing the battery is faster and cheaper.