A typical key fob battery lasts three to four years
Most car key fob batteries last between three and four years under normal use. The exact lifespan depends on how often you press the buttons, the battery type your fob uses, and whether you leave the fob in a hot car or expose it to moisture. A fob you use dozens of times a day will drain faster than one you press a few times weekly.
The most common key fob battery is the CR2032, a coin-cell battery about the size of a dime. Other fobs use CR2025, CR2016, or larger batteries like 9V cells. You can find the correct battery type printed on the battery compartment inside your fob, or in your vehicle's owner manual. Replacing the battery yourself takes less than five minutes and costs between two and five dollars.
Key Takeaways
- Key fob batteries typically last three to four years with normal use, though heavy use or extreme temperatures can shorten that time.
- The battery type is printed inside your fob's battery compartment, and you can buy replacements at any pharmacy, grocery store, or hardware store.
- A weakening fob that only works when held close to the car is a sign the battery is nearly dead and should be replaced soon.
- Leaving your fob in a hot car, exposing it to water, or pressing buttons constantly will drain the battery faster than normal use.
Signs your key fob battery is running low
Before a key fob battery dies completely, you will notice the range shrinking. If you have to stand closer to your car for the unlock button to work, or if you need to press the button multiple times, the battery is weakening. This is the time to replace it—waiting until the fob stops working entirely can leave you locked out.
Some fobs have an LED light that dims as the battery weakens. If your light is noticeably dimmer than it used to be, or if it flickers when you press a button, the battery is near the end of its life. A fob that works inconsistently—sometimes responding, sometimes not—almost always points to a dying battery rather than a broken fob.
What drains a key fob battery faster
Heavy use is the biggest factor. If you press your fob buttons dozens of times a day, the battery will wear out sooner than three years. Leaving the fob in a hot car also accelerates drain; heat causes batteries to lose charge faster. Moisture and humidity can corrode the battery contacts inside the fob, reducing how long the battery lasts and sometimes causing it to fail suddenly.
Storing your fob in a pocket or bag where it gets pressed accidentally will also shorten battery life. Some people keep their fob in a drawer or on a hook away from daily handling to extend the battery's lifespan. Extreme cold slows battery performance temporarily, but does not permanently damage the battery the way heat does.
How to replace a key fob battery yourself
Open the fob by locating the seam or slot on the edge. Most fobs have a small slot where you can insert a coin or flathead screwdriver to pry the two halves apart gently. Do not force it; if it does not budge, try the other edges. Once open, note which side of the battery faces up—this matters when you put the new one in.
Remove the old battery and set it aside. Insert the new battery with the same side facing up as the old one. Close the fob by pressing the halves together until you hear a click. Test the fob from a distance to make sure it works before you put it away. If it does not work, open it again and check that the battery is inserted the right way.
If your fob still does not work after you replace the battery, the problem is likely a broken button contact or corroded battery compartment, not the battery itself. Corrosion looks like white or green powder inside the fob. You can clean light corrosion with a cotton swab and rubbing alcohol, but heavy corrosion usually means the fob needs professional repair or replacement.
Where to buy key fob batteries
You can find CR2032 and other common key fob batteries at any pharmacy, grocery store, or hardware store. Walgreens, CVS, Walmart, and Target all stock them in the battery aisle, usually for two to five dollars per battery. Some stores sell multipacks if you want to keep spares on hand. Online retailers like Amazon also carry them, though you will pay for shipping unless you have a membership.
If you are not sure which battery your fob needs, bring the fob with you to the store and open it in front of the battery display. The battery compartment will show the type printed on the inside. Many stores will also open your fob for you if you ask at the counter.
How to extend your key fob battery life
Store your fob in a cool, dry place away from direct sunlight and heat sources. Keep it out of your car when the vehicle is parked in the sun, since the interior temperature can exceed 140 degrees on a hot day. Avoid dropping the fob or exposing it to water, as both can damage the battery contacts and cause premature failure.
Use the fob only when necessary rather than pressing buttons out of habit. If your car has a keypad entry code, use that instead of the fob sometimes. Keep the battery compartment clean and dry; if moisture gets inside, open the fob and let it air-dry before closing it again. These straightforward steps can add months to your battery's life.
Frequently Asked Questions
Can I use a different battery type if I cannot find the right one?
No. Using the wrong battery size or voltage can damage the fob's circuit board or cause the buttons to malfunction. The correct battery type is printed inside the fob for a reason. If you cannot find it locally, order online rather than substituting.
Why does my key fob battery die so fast?
Heavy use, heat exposure, and moisture are the main culprits. If your fob is in a hot car all day or you press the buttons constantly, the battery will drain faster than normal. Corrosion inside the battery compartment can also cause batteries to fail within months instead of years.
Is it normal for a key fob to stop working without warning?
Usually there are warning signs like reduced range or dimmer lights. However, if the fob gets wet or the battery contacts corrode, it can fail suddenly. Replace the battery first; if that does not fix it, the fob likely needs professional repair.
Can I recharge a key fob battery instead of replacing it?
No. Key fob batteries are not rechargeable. Once they are dead, you must replace them with a new battery of the same type. Attempting to recharge them can damage the battery and the fob.
What should I do with the old battery after I remove it?
Take it to a battery recycling program or drop it off at a store that accepts battery recycling, such as Best Buy or Home Depot. Many pharmacies and retailers also have battery collection boxes near the checkout. Do not throw batteries in the trash.