Most key fob batteries last three to four years with normal use
A typical car key fob battery runs for three to four years before it stops holding a charge. The exact lifespan depends on how often you press the buttons—someone who uses their fob ten times a day will drain it faster than someone who uses it twice a day. Temperature also matters: batteries in hot cars or cold garages age faster than those kept at room temperature.
The battery type matters too. Most fobs use a coin-cell battery, usually a CR2032, CR2025, or CR2016. These are the same batteries in watches and calculators. A CR2032 typically lasts longer than a CR2025 because it holds more charge, but the difference is usually only a few months in a key fob.
You will notice the battery is dying before it stops working completely. The fob will start working only when you hold it close to the car, or you will have to press the button several times instead of once. This is your signal to replace it soon, before it fails entirely.
Key Takeaways
- Most key fob batteries last three to four years with typical daily use, though heavy users may need replacements sooner.
- The battery type printed on your fob (CR2032, CR2025, or CR2016) determines how long it will hold charge, with CR2032 lasting longest.
- Reduced range—having to hold the fob closer to the car—is the first sign the battery is dying and replacement is coming soon.
- Replacing a key fob battery takes less than five minutes and costs between two and ten dollars, depending on where you buy it.
Signs your key fob battery is wearing out
The first warning sign is reduced range. If you normally unlock your car from twenty feet away but now have to walk to ten feet, the battery is weakening. You might also notice you have to press the button harder or multiple times to get a response, where one press used to work.
Some fobs have a low-battery indicator light on the remote itself, though not all do. Check your owner's manual to see if yours has one. If it does and the light is on, replacement is overdue.
The final stage is complete failure—the fob stops working at any distance. At this point, you still have a physical key inside the fob to unlock your car manually, so you are not stranded, but you should replace the battery right away.
What battery type your fob uses
The battery type is printed on the back of your key fob or inside the battery compartment. Common types are CR2032 (the most frequent), CR2025, and CR2016. The numbers refer to the size and capacity: CR2032 is 20 millimeters across and 3.2 millimeters thick, while CR2025 is the same width but only 2.5 millimeters thick.
You can also check your car's owner's manual, which lists the correct battery type. Using the wrong size will not damage the fob, but it may not fit properly or may not last as long. Stick with the type specified for your model.
All three types are coin-cell lithium batteries sold at pharmacies, grocery stores, hardware stores, and online retailers. They cost between two and five dollars each when bought individually, though buying a pack of two or four is often cheaper per battery.
Factors that shorten battery life
Heavy use drains the battery faster than light use. If you press your fob buttons twenty times a day—unlocking, locking, opening the trunk, and panic button presses—you will replace the battery sooner than someone who uses it five times a day. There is no way around this; more button presses mean more drain.
Heat accelerates battery aging. A key fob left on a hot dashboard or in a car parked in direct sun will lose charge faster than one kept in a pocket or bag. Cold temperatures slow the chemical reaction inside the battery, so a fob in a cold garage may seem dead but work again once it warms up—though this is temporary and the battery is still dying.
Humidity and moisture also shorten lifespan. A fob exposed to rain, sweat, or spilled drinks will corrode the battery contacts and drain the battery faster. If your fob gets wet, open it and let the battery compartment dry completely before closing it again.
How to replace a key fob battery yourself
Most key fobs can be opened with a coin or a small flathead screwdriver. Look for a seam or slot on the edge of the fob—this is where the two halves separate. Insert the coin or screwdriver and gently twist or pry until the fob pops open. Do this over a table or towel so you do not lose the small spring or contact inside.
Once open, note which side of the battery faces up (usually the positive side is facing out). Remove the old battery and set it aside. Insert the new battery with the same side facing up. Close the fob by pressing the two halves together until you hear a click.
Test the fob by standing near your car and pressing a button. If it works, you are done. If it does not, open the fob again and check that the battery is inserted the right way and that the contacts are clean. Wipe the contacts with a dry cloth if they look dirty or corroded.
When to replace versus when to repair
In almost all cases, replacing the battery is the right choice. A new battery costs two to ten dollars and takes five minutes. A repair shop will charge thirty to fifty dollars for the same job, and the fob will work exactly as well afterward.
The only time repair makes sense is if the fob itself is broken—the buttons do not click, the case is cracked, or the circuit board is damaged. In that case, a repair shop can replace the internal components, but this is rare. Most fobs fail because the battery is dead, not because the fob is broken.
If you are uncomfortable opening the fob yourself, a car dealership, locksmith, or battery retailer can do it for you. Many pharmacies and electronics stores also offer battery replacement for a small fee, sometimes free if you buy the battery from them.
Storing your key fob to extend battery life
Keep your fob in a cool, dry place when you are not using it. A pocket, bag, or drawer at room temperature is ideal. Avoid leaving it on a hot dashboard, in direct sunlight, or in a humid bathroom.
If you have a spare fob, rotate between them. Using one fob for a week and then switching to the other gives each battery a rest and can extend the overall lifespan of both. This is especially useful if you use your fob heavily.
Do not store the fob with the battery removed for long periods. Lithium batteries can lose charge even when not in use, and storing them separately does not help. Keep the battery installed and the fob in a cool place instead.
Frequently Asked Questions
Can I use a different battery type if I cannot find the right one?
Not recommended. Using the wrong size can cause poor contact with the fob's terminals, leading to intermittent failures or a shorter lifespan. The correct battery type is inexpensive and widely available, so it is worth waiting a day or two to get the right one rather than using a substitute.
Why does my key fob battery die so fast?
Heavy use, heat exposure, and moisture are the main culprits. If you press your fob buttons dozens of times a day or leave it in a hot car, the battery will drain faster than the typical three to four years. Check that the battery contacts are clean and that the fob is not exposed to water or extreme temperatures.
Is it normal for a key fob battery to last only a year?
No, one year is shorter than normal. This usually means the fob is being used very heavily, stored in a hot location, or the battery contacts are corroded. Open the fob and inspect the contacts for dirt or corrosion. If they look clean, try a fresh battery and monitor how long it lasts.
Can I recharge a key fob battery instead of replacing it?
No. Coin-cell lithium batteries like those in key fobs are not rechargeable. Once they are dead, they must be replaced. Attempting to recharge them can damage the battery or the fob.
What should I do with the old battery after I remove it?
Take it to a battery recycling program or a retailer that accepts used batteries. Many electronics stores, pharmacies, and municipal hazardous waste facilities will take old batteries for free. Do not throw it in the trash.