Do you own a Mercedes? Do you find yourself stressing about key battery life, wondering whether it’ll work when you need it most? Have no fear; in this blog post we provide an easy-to-follow guide on how to change Mercedes key battery.
From understanding the basics, such as what type of battery your car uses, to intricate step-by-step instructions for replacing the old battery with a fresh one – everything is covered here! So if your Mercedes key isn’t working as well as it used to, read on to discover exactly how to change its battery and breathe some new life into it.
What Type of Battery Does My Mercedes-Benz Key Fob Need?
If you own a newer Mercedes-Benz Chrome SmartKey®, then you’ll need one CR 2025 battery. This type of battery is commonly found in watches, calculators, and other small electronic devices. However, if you have one of the older SmartKey®, then you’ll need two batteries instead of just one.
Can You Use CR2032 Instead Of CR2025 in Mercedes Key?

Some drivers have reported that using a CR 2032 battery in place of a CR 2025 battery can actually improve the range of their Mercedes key fob. Despite the slight difference in physical size, the voltage of both batteries is the same, which means that the CR 2032 battery can be used as a replacement without any issues.
How to Open Your Mercedes-Benz Car Key Fob to Replace the Battery
The method for opening a Mercedes-Benz key fob is dependent on the type of key you have, whether it is a Chrome Key or a Smart Key. Here are the steps to follow for each type of key fob:
Mercedes-Benz Chrome Key:
Start by pulling down on the bottom silver, square-shaped piece of the key. Pull it back as far as it can go until it releases. Once the key comes apart, you will notice a small gap in the fob. Press the key into the flat, narrow end of the fob, and this will open the key cover.
Mercedes-Benz Smart Key:
Pull the latch located at the end of the key fob, and the key will come out of the holder. You will then see a slot at the end of the key fob. Use the key to push into the slot, and this will open the battery compartment.
Mercedes-Benz Key Fob Battery Replacement: Step-by-Step
Replacing the battery in your Mercedes-Benz key fob is a straightforward task. But before you get started, take stock to determine if it’s a Chrome SmartKey® or an earlier model of the same type. Once you know the type of key fob you have, follow these steps to replace the battery.
How to Replace the SmartKey® Battery for Older Mercedes Models
1. Flip your key fob over, and locate the two small screws on the back plate.
2. Insert a standard Phillips head screwdriver into each screw and unscrew them to remove the back plate.
3. Take out the old batteries, ensuring that you note their orientation – they must be installed in exactly the same order in which they were removed.
4. Insert two new CR 2025 batteries into the battery compartment, making sure that their positive (+) and negative (-) terminals are facing correctly as before.
5. Once both batteries have been inserted, reattach the backplate by screwing it on tightly with your Phillips head screwdriver
6. Test your key fob to make sure it functions correctly.
How to Replace the Chrome SmartKey® Battery for Newer Mercedes Models
1. Flip your key fob over, and locate the two small screws on the back plate.
2. Insert a standard Phillips head screwdriver into each screw and unscrew them to remove the back plate.
3. Take out the old battery, noting its orientation – it must be installed in exactly the same order as before.
4. Insert one new CR 2025 battery into the battery compartment, making sure that its positive (+) and negative (-) terminals are facing correctly as before.
5. Once the battery has been inserted, reattach the backplate by screwing it on tightly with your Phillips head screwdriver
6. Test your key fob to make sure it functions correctly.
When To Replace Your Mercedes-Benz Key Fob Battery?
Generally speaking, these batteries last between 3 and 4 years before needing replacement. However, if you’re having trouble with your push-button start, it’s likely that your key fob battery is to blame. When your battery is running low, your car may not recognize the key fob, causing you to have to try multiple times to start your engine.
Why is my Mercedes key not working after battery change?
Is your Mercedes key not working after a battery change? Don’t panic! There could be several reasons why your remote key fob isn’t functioning.
One possible culprit could be the internal contacts, such as the buttons or battery connector terminals. Another possible scenario is that your car and remote unpaired after the battery replacement.
It’s also worth checking for loose buttons, broken locks, deprogramming, damaged keys, or even electrical issues.
Can a Mercedes-Benz key fob be reprogrammed?
Well, if you have a Mercedes, the answer is no. Once a key has been programmed to one car, it stays with that car for life. This is because Mercedes keys pair “for life”. Once you stick the key in the ignition and it works, it’s never going to work in another car. While this may be frustrating for some, it’s also a security feature that ensures your car is less likely to be stolen.
What if changing the battery in Mercedes key fob doesn’t fix the issue?
If changing the battery doesn’t fix the issue, then it’s likely that you’ll need to replace your key fob. You can do this by getting a new key from your local Mercedes dealership, or look online for aftermarket options.
FAQs about How To Change Mercedes Key Battery?
Can I change Mercedes battery myself?
Yes, you can change your Mercedes key fob battery yourself. All you need is a Phillips head screwdriver and two new CR 2025 batteries.
What happens if the key fob dies while driving?
If your key fob battery dies while the car is in motion, there is nothing to fear. The car will continue to operate as normal since the key fob is only used for unlocking and starting the engine. The key fob has no effect on the engine or ignition once the car is in motion.
Luckily, replacing the battery in your key fob is a quick fix that only takes a couple of minutes. So, if you find yourself in this predicament, simply head over to a store to pick up a new battery and you’ll be up and running in no time.
Conclusion
In conclusion, replacing the battery in your Mercedes key is a simple task that you can easily do on your own. By following the steps outlined in this article on how to change Mercedes key battery, you can save time and money by avoiding a trip to the dealership or a mechanic.
Remember to use the correct battery type, handle the key with care, and dispose of the old battery properly. With a fresh battery, you can ensure that your Mercedes key continues to function smoothly and reliably.

I’m Timothy Ballard, owner of a used car dealership in Springfield. I love just about everything automotive, but I have a special place in my heart for trucks. I’m an ASE Certified Master Technician, so I know my way around a car. In my spare time, I enjoy traveling with my family and hiking new trails.