The Real Trick to Installing Key Fob Replacement Batteries

It’s time to talk about the other battery for your car. The one in your car key fob.

All batteries wear out over time. Are you pushing the unlock button a couple of times before your car responds?

It might be time for a key fob replacement battery.

The battery in most car key remotes, transponders and key fobs isn’t easy to access. You could visit a dealership, car repair shop and even your favorite battery store to ask for a pro to replace the key fob battery for you.

On the other hand, you can replace a dead car key fob battery yourself.

Replacing a car key fob battery is easier than replacing an actual car battery. It does take some work and a fresh lithium battery. Also, if you’re not careful, you may need a whole key fob replacement. (You do have aftermarket options if you do need to replace a car key fob.)

Is your car key fob not working? There’s good news. You may already have everything you need to give your car key remote new life.

Yes, You Can Replace Key Fob Batteries Yourself

Putting in a new key fob battery can be easy with the right tools:

• A thin blade, such as a watch knife, for prying open the case
• A replacement battery, usually a CR2032 coin cell that’s available in most retail locations
• A precision screwdriver, between 1.4mm or 2.4mm, depending on the fob
• Tweezers to grab the battery
• Your phone for reference photos

Installing a key fob replacement battery is simple:

1. Pry open the fob’s plastic case.
2. Pull out the old battery.
3. Put a new key fob battery in.
4. Snap the case shut.

Store manager Joseph De La Rosa at Interstate All Battery Center of Surprise, Ariz., shows how it’s done. | Video: Joseph De La Rosa

Check Your Key Fob Case for the Replacement Battery Size First

Your key fob case may show which battery size it needs. Look on the back of your car key fob or inside the key sleeve for embossed letters.

You don’t want to find out you bought the wrong key fob replacement battery when you’ve taken it apart. Most car key fob batteries use a standard watch battery, the CR2032 coin cell, but it can vary, depending on the year, make and model of your car. For instance, the Honda CR-V needs a CR1250 battery. Most car key fobs take just one battery, but the Ford Mustang key fob takes two.

Then again, your car key fob may not show which new battery to buy.

In that case, you’ll need to open it gently.

Opening a key fob with a watch knife is easy, as Mike Harris, Interstate All Battery Center manager of production and engineering shows. | Image: Mike Harris

Wedge Your Pry Tool Around the Case to Open Your Key Fob

Pry your car key fob open gently. Do not force it. When you get the fob case open, the temptation may be to pull it apart from just that hole. That’s a guaranteed way to need a key fob replacement.

Instead, wedge your flathead screwdriver or watch knife around the outside of the case. Some key fob cases have a notch to help you get started. Once you have the first gap, wedge your pry tool around the case’s fasteners, like you’re peeling an apple or orange. It doesn’t take much pressure to pop the fasteners open.

Make sure you don’t apply too much pressure. Otherwise, it might pop open and scatter fob parts across the living room.

Always Take a Picture After Opening Your Key Fob

Car key fobs can vary significantly inside, even for the same year, make and model of car.

Take a photo of the key fob before you remove the battery so you can refer to it later. This simple precaution can save you from having to buy a key fob replacement because not all the parts are going back in the way they should.

You’ll also know for certain whether the positive side of the battery goes up or down.

Do Not Disturb the Wiring or Circuit Board Inside Your Key Fob

Avoid messing with the wiring inside, or else you really will be in the market for a key fob replacement.

Use tweezers or another precision tool to lift the battery out of its frame. Some fobs have a fastener or a sliding piece of metal to hold the battery securely to the circuit. You’ll need to move them out of the way to remove the battery, but do not pull out the circuit board or antennas.

Electricity stored in the circuits keeps the car key fob programmed to your car. Don’t disturb them. Otherwise, you may find yourself having to take the remote to the dealership (or select Interstate All Battery Center locations) to program a new car key fob replacement.