How to change car key fob battery

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Maybe you have to press the button multiple times to get the doors to unlock or perhaps your car battery fob doesn’t have the range it used to. Key fobs and other car remote controls run on batteries that need to be replaced when they run out of power – so this may be due to a dying battery.

The process is generally pretty straightforward but it sometimes varies depending on brand or even a model.

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What batteries are in the car key fobs?

CR2032 battery used for car key fobs
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Vast majority of car manufacturers use the coin-like CR2032 or CR2025 batteries (traditionally used for watches, kitchen scales and other extremely low power applications). These batteries are simple to fit in small enclosures and replacements are easily accessible.

We have done our best to identify which one you need but we suggest to check the vehicle’s manual to make sure you have the right one.

There are many manufacturers making these batteries but you can’t really go wrong with the ones below:

Ford car key fob battery replacement

  • First, you have to push down on the release button at the back of the key – best with your thumb nail
  • Pull the key apart
  • Once you separate the cover, you will need to pop the central piece off
  • Pop the piece out with a coin (or your new battery)
  • Make sure the new batteries are facing the correct way and put it in
  • Put the batteries in (you will need 2x CR2025)
  • Put back the 2 pieces

These steps should work with the following Ford models (among others):

  • 2016 Ford Explorer
  • 2016 Ford Edge
  • 2016 Ford F-150
  • 2016 Ford F-250
  • 2016 Ford F-250 Super Duty
  • 2016 Ford F-350
  • 2016 Ford F-350 Super Duty
  • 2016 Ford F-450 Super Duty
  • 2016 Ford F-550 Super Duty
  • 2016 Ford Fusion
  • 2016 Ford Mustang
  • 2015 Ford Edge
  • 2015 Ford F-150
  • 2015 Ford F-250
  • 2015 Ford F-250 Super Duty
  • 2015 Ford F-350
  • 2015 Ford F-350 Super Duty
  • 2015 Ford F-450 Super Duty
  • 2015 Ford F-550 Super Duty
  • 2015 Ford Fusion
  • 2015 Ford Mustang (with smart key)
  • 2014 Ford Fusion
  • 2013 Ford Fusion

The following models/years will require CR2450 battery for their fob:

  • Ford Expedition – 2018 , 2019 , 2021, 2022
  • Ford Explorer – 2018 , 2019 , 2020, 2021, 2022
  • Ford Edge – 2017 , 2018 , 2019 , 2020, 2021, 2022
  • Ford Escape – 2020, 2021, 2022

How to replace the key fob remote battery for these:

  • Press down the button on the top of the key and remove the emergency physical (metal) key
  • Use the key to pry open the cover (with Ford logo on it) by inserting it into the small space just under the lid and giving the key a little twist
  • You will then see the battery
  • Use a small screwdriver or something similar to pop the battery out
  • Replace the battery (CR2450)
  • Put the lid back

Hyundai car key fob battery replacement

  • Remove the key out of the key fob but pushing the button and pulling the key out
  • Push in and turn the key into to slot next to the key hole
  • The key will pop open – it is best to keep the key buttons facing down so they don’t fall out
  • Remove the board cover and the board out
  • Remove the battery
  • Put the new battery in (CR2032) plus side down
  • Put the board and the board cover back
  • Put the two halves together
  • Slide the key back

Jeep car key fob battery replacement

The following steps apply to: Jeep Compass / Renegade / Liberty / Cherokee / Grand Cherokee.

Batteries needed: CR2032

  • Release the key by pulling down the little latch on the side of the for where the Jeep logo is and pull out the key
  • Insert the key to the small hole above the main key hole (see the video below) and split the fob in two parts by twisting the key
  • In one half there is the circuit board while the battery is in the other half
  • Change the battery (best to use a small screwdriver)
  • Put everything back together
  • Put the key back in

Kia car key fob battery replacement

  • Hold and pull the top metal part of the fob – you will pull out the reserve metal key
  • Take a flathead screwdriver and put it into the hole opposite of the key hole
  • Turn and wiggle gently to open the fob along the side of the fob
  • Once it is open, the circuit board will probably fall out but don’t fret
  • Take the screwdriver again and pry the battery out but lifting it out of its place
  • Replace the battery (CR2032) and click it back into place
  • Return the circuit board and line it with the rubber lining inside the key
  • Click the fob cover back into its place

Mercedes car key fob battery replacement

To open a Mercedes-Benz Chrome Key and replace the battery:

  • First, you have to push down on the silver, square-shaped button on the bottom of the key
  • Slide off the bottom cover
  • Once you separate the cover, you’ll see a small drawer in the fob
  • Pull the drawer out and pop off the old battery
  • Make sure the new battery is facing the correct way and put it in
  • Slide the cover back

What battery does Mercedes key take?

The battery type for your Mercedes-Benz key fob should always be CR 3025 or CR3032. The Smart Key uses two 3-volt CR 2025 batteries while the Chrome Key uses just one.

Mercedes car key fob replacement (W204)

There are a few variations of Mercedes SmartKeys and the methods you use to replace the batteries. This video shows the SmartKey where the batteries plastic carrier slides out from the back of the key (for example C300 uses this design).

What battery does the W204 use? This SmartKey / key remote uses two 3V CR2025 batteries.

Mercedes C300 (W204) SmartKey Battery Replacement is a straightforward enough process:

  • Take out the key using the small latch on the top of the key
  • Insert the wide end of the key into to fob as shown in the video and use it as a lever to extract the fob internals from the casing
  • You will see 2 batteries – slide them out and replace them with the same model (CR2025)
  • Slide the fob internals back to the casing
  • Insert the key back into the fob

Mercedes car key fob replacement (W205)

Typically, W205 would be C-class cars from 2015.

What battery does the W205 car remote keys take? It takes the CR2025 batteries

  • Hold the remote buttons down
  • Pull the latch and slide out the emergency physical (metal) key – it will eject from the “top” horizontal half of the key
  • Slide in the key into the “bottom” half of the key about 1cm (gently)
  • The back cover will pop out
  • Remove the battery
  • Put in a new CR2025 with positive terminal on the top
  • Close the lid
  • Re-insert the key

Here is a step by step video:

Mercedes car key fob replacement (W206) – 2021 and 2022 cars

The newest S Class Mercs should not be running out of their car key fobs just yet but just in case yours has, below is how you change that one.

Before you start, you might wonder what battery does the 2022 S Class remote take? – It takes the CR2032 battery.

Steps to change the battery:

  • Press the button on the back of the key fob and pull out the emergency physical key
  • Use the key the pry open the remote fob but sliding the key a bit into the fob on its top side and giving it a half a twist.
  • The back will come off
  • Take the emergency metal key and gently pry open the small plastic lid in the centre of the fob
  • The battery will then come out
  • Slide in the new CR2032
  • Put the small plastic lid back (watch the latches)
  • You should be able to test the remote now by pushing the button and you should see the red dot on the remote flashing
  • If everything is good, slide back the back cover and you are done

Here is a handy video by Key Fob Rob showing the process:

Mini car key fob battery replacement

  • Remove the integrated key from the vehicle key by pushing the button and pulling at the same time
  • Push the integrated key into the hole to access the battery compartment
  • Push the integrated key into the battery compartment and lift the lid
  • Lift the battery out
  • Insert a new battery (CR2032) – the positive side facing up
  • Put lid and the cover back
  • Insert the integrated key until it engages

Toyota car key fob battery replacement

  1. Remove the key from the fob. There’s a little metal button right above the key part of your key fob. Press that button, and pull out the key.
  2. Open the fob. Fit a small screwdriver or some other flat object into the little slot that the key fits into, and pop open the fob.
  3. Remove the green circuit board. Do this gently, so as not to damage the components.
  4. Replace the battery. Take note of the kind of battery you need to replace, which should be written on a label on the original battery. You can also find this in your owner’s manual; most Toyota key fobs require a CR 2032 3V. You can find a replacement battery at most electronic stores, or you can order one online.
  5. Put the fob back together, and place the key back in the fob.

Vauxhall car key fob battery replacement

Changing the car key fob battery for Vauxhall/Opel is one of the most straightforward ones.

  • Open the key
  • Open the fob by pushing on both sides of the fob in the gap where the metal key sits
  • Pop the battery out using tweezers or something thin and sharp
  • Replace the battery (CR2032)
  • Close the fob

Volkswagen car key fob battery replacement

For changing a battery in a VW key fob, you will need a CR2032 or CR2025 3V battery. These are circular batteries that look like small discs (generally the same ones that you put in kitchen scales, clock, etc.). Whether CR2032 or CR2025 depends on a model but the principle is the same for all. You’ll also need a tool to pry out the battery, like a small flat-blade screwdriver.

  1. Flip open the key by pressing the metal button.
  2. Locate the battery panel of the key, right beneath the Volkswagen logo.
  3. From the now-empty key cavity, push up on the panel.
  4. Remove the battery panel.
  5. Insert the prying tool into the slot and apply a bit of force.
  6. Set aside the old battery.
  7. Place the new battery in slot with + symbol facing you.
  8. Snap the new battery into place.
  9. Replace the battery panel.
  10. Close the key.
  11. Enjoy your now fully-functioning and working key fob!

Here is a handy video explaining the process.

Note: Once the battery is changed you may have to re-sync your Volkswagen key fob or it will not work. You may think your car does not have a key lock but it does – it is hidden, though! The driver’s side door handle will have a small slot under the handle cover. Take a look under the handle and you will see it! Insert your physical key into the slot and gently pry the cover off. This will now reveal the key insert. Insert your physical key into the door lock and turn it clockwise to unlock position. Remove the key and press the unlock button on the fob. The doors should now open. If the alarm kicks in (yikes) enter the vehicle, insert the key into the ignition and start the car – the alarm will stop and your key is re-synced. German over-engineering, who knows why it is so complicated.


What is the difference between CR2032 and CR2025 battery

The obvious difference between the two battery types would be thickness. The CR2032 is 3.2mm thick while the CR2025 is 2.5mm thick. Because the CR2032 is 0.7mm thicker than the CR2025, it has a slightly higher capacity (mAh) to deliver current to the load – the CR2032 can deliver 225mAh with a thickness of 3.2mm, while the CR2025 only delivers 160mAh with a thickness of 2.5mm.

Can I use a CR2032 battery instead of a CR2025? Yes, you can use a CR2032 instead of a CR2025. Both batteries share the same voltage. However, the only concern is that the CR2032 is bigger (in depth, not diameter) than the CR2025. So it all comes down to whether the battery compartment that holds the CR2025 can accommodate the CR2032 as well.

What battery can replace CR2450?

The 3V CR2450 battery should only be replaced with another CR2450 battery.

CR2450 vs CR2025 – what is the difference?

The main differences between CR2450 and CR2025 batteries are their physical dimensions, capacity, and voltage:

  1. Physical Dimensions: CR2450 batteries are larger and thicker than CR2025 batteries. The diameter of a CR2450 battery is about 24.5mm, while the diameter of a CR2025 battery is about 20mm. The thickness of a CR2450 battery is about 5mm, while the thickness of a CR2025 battery is about 2.5mm.
  2. Capacity: CR2450 batteries typically have a higher capacity than CR2025 batteries. The capacity of a battery is a measure of how much charge it can store, and it is usually measured in milliampere-hours (mAh). CR2450 batteries typically have a capacity of around 600-700mAh, while CR2025 batteries typically have a capacity of around 150-170mAh.
  3. Voltage: Both CR2450 and CR2025 batteries have a nominal voltage of 3V, which is the standard voltage for most coin-cell batteries.

Car key fob still not working?

If your car key fob is not working after switching out the battery, then the fob itself could be malfunctioning. There is also a chance that it could be a mechanical issue. There may be ways to fix this yourself, but the easiest way to make sure it’s fixed and done correctly is to have a professional do it for you. Electrical components can be very tricky to repair without proper know-how.

How long does car key battery last?

The battery in the car key fobs usually last about 3-4 years, depending on how often it is used but most importantly, how the fob is stored as hot/cold temperatures impact the batteries.

What happens when key fob battery is low?

At first, you will start noticing that the key has lost its range so you need to be closer to your car for it to respond. Then it will slowly stop responding even from close range.

How much does it cost to replace the battery in the car key fob?

Changing the battery in the key fob is probably the cheapest fix ever, the batteries cost about $6 or £5, depending on brand, etc. Time-wise it will cost you about 5 minutes the first time, if you have done it before, about 30 seconds.

Will a dead key fob cause car not to start?

If the keyless entry system does not detect the key fob inside the vehicle, it will not start the engine. If the battery in the key fob is dead, the system may not be able to detect the presence of the key fob and therefore will not start the engine. Conversely, if you want to secure your car and be sure your remote doesn’t get used to open and start the car, you might want to use a car key fob Faraday pouch – we have reviewed a few good ones here.

How does the coin battery work?

The lithium coin battery (for example, a CR2032) has a lithium metal anode and a manganese dioxide (MnO2) cathode. The battery has a polypropylene separator and an electrolyte comprised of a lithium salt compound in an organic solvent. The chemical reaction is Li + MnO2 -> LiMnO2. The cross section view of a CR2032 in figure 1 shows how coin cells are typically constructed. The Li/MnO2 chemical system generates a nominal voltage of 3V. (Source: Hoffmann and Furset, 2011)

CR2032 battery diagramm cut schema


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