Modern car key fobs allow you to remotely lock and unlock your doors, operate your windows, and even start your car. Like all remote controllers, however, car key fobs can only work when they have sufficient battery power. So how long do car remote batteries last? We've done the research for your reading pleasure.
Battery life may vary depending on the frequency of usage, but many modern car remote batteries typically last between three to four years.
If you want to know more about your car remote's battery as well as your car's key fob, then you've come to the right place. Do read on, and we'll help you understand more.
How Often Should You Replace Your Car's Remote Battery?
Most car key remotes or key fobs use 3-volt lithium coin batteries, particularly the CR2032. However, some key fobs use different coin batteries, such as the CR2450, CR2025, and CR2016. Although these batteries have the same voltage, they differ in size and capacity.
A CR2032 has a 20 mm diameter, a 3.2 mm thickness, and a charge capacity of 240 mAh. On the other hand, the CR2450 has a 24 mm diameter, a 3.2 mm thickness, and a charge capacity of 486 mm. In short, the thicker the coin battery is, the longer it can last with the same usage.
However, we also have to take note that not all key fobs consume the same amount of battery power.
For example, some key fobs can work from a maximum range of 15 feet, and others can work at 100 feet. Furthermore, some key fob commands require long button presses, such as window operation. More range and longer button presses mean more power consumption.
Nevertheless, key fob manufacturers use an appropriately-sized battery that can handle their key fob's power requirements for years of normal usage.
In terms of shelf life, lithium coin batteries have an expiration period of 10 years after production. This means that even if they remain unused, the batteries may lose their charge or fail to function properly after a decade.
Under normal key fob usage, lithium coin batteries can last for approximately three to four years.
How Do I Know If My Key Fob Needs A New Battery?
Like in many battery-operated electronic items, you will notice some signs when your key fob battery becomes weak.
Shorter Signal Range
You may notice that your car doesn't respond to your key fob's button commands from the same distance as before. This can be a sign that your battery doesn't have enough power to send out the RFID signal from the same distance as before.
If you need to be practically standing beside your car before your key fob buttons work, then it may be a good time to replace your battery.
Repetitive Button Presses
There may be times when a single button press on your key fob isn't sufficient to lock, unlock, or start your car. If your car's response to your key fob buttons is inconsistent, then your battery might be getting weaker.
If your car's response to your key fob is slow or delayed, then your key fob's battery may not be powerful enough to sustain the remote signal.
When you need to press and hold your key fob buttons to make your car respond to normal press and release button commands, then your battery may be weak.
Is It The Key Fob Or The Battery?
While dead batteries are often the cause of failing key fobs, the key fobs themselves can sometimes malfunction. Before you go out to replace your key fob or your battery, you can test both to isolate the problem. With these helpful tips, you can save some money.
Test Your Spare Key Fob
One of the easiest ways to test a failing key fob is with a spare key fob. Modern cars usually have two key fobs provided by the dealership. If the spare fob works properly, then you know that your main key fob has a problem.
Make Sure That The Key Fob Is Transmitting
To check if your key fob is sending out an RFID signal, you may use a radio frequency remote tester. Here's a helpful video on using a remote tester.
Aside from testing your key fob's transmission, the remote tester can also recognize your key fob's signal frequency.
Use Your Television
If you know your key fob's signal frequency, then you can try using a smart T.V. to help you test your check your key fob's transmission. See another helpful video below to learn more about this convenient method.
As shown in the video above, here are the steps in using a smart T.V. for your key fob testing.
- Turn on the smart T.V.
- Go to Settings and find "Tuning," then "Manual Store," then "Search."
- Under "Search," choose your key fob's frequency.
- Bring your key fob within a few feet of your T.V., then press a key fob button.
- Your key fob should disrupt your smart T.V.'s screen if the fob is indeed transmitting.
In general, key fobs in Japan and in the U.S. use a 315 MHz signal frequency, while European key fobs use 433.92 MHz.
Interpret The Results
After using either of the testing methods above, you can interpret the results to isolate the key fob's problem.
- If all key fob buttons are transmitting, but the car does not respond to the button commands:
- The key fob needs reprogramming, or
- Your car's remote keyless entry (RKE) module or body control module (BCM) has a problem, or
- Your car has some blown fuses, or
- The car's 12-volt battery is discharged.
- If all your key fob buttons transmit weakly or intermittently, then your key fob's battery needs replacement.
- If all your key fob buttons transmit a signal, but the car only does not respond to all button commands:
- The key fob needs to be reset or reprogrammed, or
- The car's RKE module and/or BCM have problems, or
- The car's electromechanical parts (e.g., alarm, tailgate, power locks, etc.) may have problems.
- If only some fob buttons transmit, but the car responds properly to these working buttons' commands:
- Some key fob buttons may have dirt or physical damage, or
- The key fob's circuit board might have some dirt or corrosion
- If none of the fob buttons are transmitting any signal:
- Your fob's battery is deeply discharged, or
- Your fob's RFID transmitter is damaged, or
- The fob's circuit board is extremely dirty, or
- You need a new key fob
If you interpret your results and isolate the problem to your key fob's battery, then you can still test the battery's state of charge. Is it just weak, or is it completely discharged? The next section will help you find out.
How Do I Test My Key Fob's Battery?
You can use a multi-tester to check your key fob battery's remaining charge.
- Set the multi-tester to "D.C. voltage."
- Place the tester's black lead on the top center of the battery (the face with no writings).
- Place the tester's red lead on the side of the battery.
- Check the voltage reading on the tester.
For a 3-volt lithium coin battery, a reading lower than 2.5 volts means that the battery is weak or discharged. Brand-new coin batteries can have readings higher than 3 volts.
Why Is My Key Fob Battery Draining So Fast?
Some car owners may find that their key fob's batteries are dead after only a few weeks or months of usage. There are a few reasons why a key fob's battery drains very fast.
Key Fob Buttons Get Pressed By Accident
If you put your key fob in a tight pocket or in your bag, you might be accidentally pushing the buttons. With every button press, your key fob drains your battery's charge. If you want to have your key fob with you at all times outdoors, then you should avoid getting it squeezed or pressed.
A key chain that you can hook to your belt buckle or your bag strap may be a good idea.
Key Fob Is Stored Too Close To The Car
Modern car key fobs have both active and passive RFID chips. The active chips activate when you press a button on your key fob. The passive RFID chip, on the other hand, acts like a proximity receiver. It communicates with your car's RKE module to let the car know that you are nearby.
If you store your key fob near your car, say on a hook in your garage, then your car and your key fob will keep communicating. If they are too close to each other, the constant communication will drain your key fob's battery.
Battery Contact Points Are Dirty
If your key fob's battery contact points are dirty or corroded, then your key fob may be grounded and draining the battery's charge quickly. You may want to try some DIY cleaning. Here's a helpful video about cleaning your key fob's circuit board and contact points.
Key Fob Is Stored In Places With Extreme Temperature
Battery life shortens at extreme temperatures. If you expose your car key fob to extreme heat or cold regularly, you may shorten its usable life.
Car remote or key fob batteries typically last between three to four years with normal usage. However, with improper key fob usage or storage, the battery life may shorten significantly. You should always take care of your key fob.
Thank you very much for reading. We hope that we were able to help you understand more about your key fob, its battery, and how to take care of them.
For more interesting reads about key fobs and other automotive topics, please check out these great articles below.