How to Change the Battery in the Key Fob - Key Fob Battery Replacement
When the key fob starts to react more slowly and when it requires to be near the car in order to open it, it is time to replace the key fob battery.
Key fobs almost exclusively feature lithium button/coin cells, which feature long shelf life and stable output voltage and are able to provide relatively strong current pulses required by the internal key fob electronics.
For most cars, the key fob battery can be replaced at home with minimum additional tasks required afterward.
Updated: September 5, 2023.
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Car Fob Battery Chemistries
Car fob batteries are based almost exclusively on one of the lithium battery chemistries, including:
Lithium Manganese Dioxide (Li-MnO2) is a non-rechargeable type of lithium battery chemistry, featuring a nominal voltage of 3.0 volts, an open-circuit voltage of up to 3.3 volts, and a cutoff voltage of 2.0 volts.
The most common label of the Lithium Manganese Dioxide (Li-MnO2) battery is "CR," for example, "CR2032".
Lithium Manganese Dioxide (Li-MnO2) chemistry is the most popular non-rechargeable lithium battery chemistry and is commonly used in 3V lithium button/coin cells and 3V lithium cylindrical batteries.
Lithium Manganese Dioxide (Li-MnO2) chemistry features stable output voltage, good capacity, low self-discharge rate, wide temperature operating range, strong pulse currents, etc.
Note: Although Lithium Carbon Monofluoride (Li-(CF)x) non-rechargeable lithium batteries ("BR," for example, "BR2032") feature a nominal voltage of 3.0 volts (older batteries 2.8 volts), a cutoff voltage of 2.0 volts (older batteries 2.25 volts), an open-circuit voltage of 3.1 volts and are generally compatible with Lithium Manganese Dioxide (Li-MnO2) chemistry, Lithium Carbon Monofluoride (Li-(CF)x) batteries are not used in car key fobs because these batteries are unable to withstand relatively large pulse currents.
Vanadium Lithium rechargeable button/coin cell batteries are very similar to Manganese Dioxide Lithium (MnO2-Li) rechargeable batteries, sharing the same nominal voltage of 3.0 volts.
Vanadium Lithium rechargeable batteries are labeled as "VL," for example, "VL2020" or "VL2032".
Lithium-ion rechargeable batteries are available in several chemistries, including Lithium Manganese Oxide (LiMn204, IMR), Lithium Manganese Nickel (LiNiMnCoO2, INR), Lithium Iron Phosphate (LiFePO4, IFR), Lithium Cobalt Oxide (LiCoO2, ICR), Lithium Nickel Cobalt Oxide (LiNiCoO2), Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2), etc.
Lithium-ion batteries feature a smaller capacity than "CR" batteries but can withstand hundreds of charging/discharging cycles.
However, their nominal voltage depends on the exact battery chemistry and ranges from 3.2 to 3.7 volts.
The common label of rechargeable lithium-ion batteries is "LiR," for example, "LiR2032".
When replacing the old key fob battery with a new one, be sure to go for exactly the same battery chemistry.
For more about this topic, feel free to check our Types of Lithium Battery Chemistries article.
Car Fob Batteries By Size
Key fob batteries differ in size, and hence, they all have different discharge characteristics - voltage, capacity, pulse currents, etc.
When replacing the old battery with a new one, it is also important to go for a battery of the same size, or the battery will not fit properly, causing various issues.
In order to figure out which battery is needed, the best thing to do is to check the car manual and/or to open the car key fob without removing the battery.
Lithium Manganese Dioxide (Li-MnO2) non-rechargeable 3.0V CR1632 battery features physical dimensions of (D x H) 16.0 x 3.2 mm (~0.63 x 0.126 inches), a nominal voltage of 3.0 volts, a cutoff voltage of ~2.0 volts, a nominal capacity of around 130-140 mAh with the standard continuous discharge current being around 0.1-0.2 mA.
Note that the "CR1632" battery is the most common label, but there are also other labels as well, including DL1632 (used by Duracell), ECR1632 (used by Energizer), and similar, but they are all "standard" CR1632 batteries.
Rechargeable button/coin 16.0 x 3.2 cells are rarely used in car key fobs, but it is good to know that there are generally three different rechargeable chemistries in use:
- Vanadium Lithium VL1632 battery: 3.0V, 25 mAh,
- Manganese Lithium ML1632 battery: 3.0V, 40 mAh,
- Lithium-Ion LiR1632 battery: 3.2-3.7V, 70 mAh.
Never, but really, never use the batteries of different chemistries unless explicitly allowed by the key fob manufacturer.
CR2016 batteries are non-rechargeable lithium button/coin cell batteries featuring physical dimensions of 20 x 1.6 mm (0.7874 inches x 0.06299 inches).
Their nominal voltage is 3.0V, and the cutoff voltage is typically 2.0V.
The nominal capacity CR2016 battery is ~90 mAh, with a maximum continuous discharge current of 1 mA, a nominal continuous discharge current of 0.1 mA, and a maximum pulse current in the 5 mA and 15 mAh range, ensuring good power levels required by remote key fobs.
While CR2016 is the standard label for Lithium Manganese Dioxide (Li-MnO2) batteries, other labels are used as well, including DL2016, ECR2016, E-CR2016, SB-T11, 5000LC, etc.
Rechargeable LiR2016 batteries are rarely used. They feature 3.2-3.7 volts nominal voltage and a nominal capacity of ~20-25 mAh.
CR2020 and VL2020 Batteries
Lithium CR2020 and VL2020 batteries are coin-cell batteries featuring physical dimensions of 20 x 2.0 mm (~0.7874 x 0.0787 inches).
CR2020 batteries are non-rechargeable batteries featuring a nominal capacity of 110-130 mAh, while rechargeable VL2020 batteries feature a typical nominal capacity of ~20 mAh.
While rechargeable batteries are not very common in car key fobs, some brands use them quite often in some models, with or without soldering tabs.
Lithium non-rechargeable CR2025 batteries feature physical dimensions of (d x H) 20 x 2.5 mm (~0.7874 x 0.0984 inches).
Their typical capacity is around 160-170 mAh, with a typical discharge current of ~0.2-0.3 mA.
CR2025 batteries are one of the most popular car key fob batteries and feature many labels, including 2025, CR2025, DL2025, DL2025B, ECR2025, KCR2025, SB-T14, LF12V, 5003LC, CR2025-1W, L12, LM2025, 208-205, etc., leading to certain confusion among the users - fortunately, manufacturers almost always use the standard label of "CR2025" as well.
Rechargeable LiR2025 batteries are not as common in car key fobs - LiR2025 batteries feature a nominal voltage of 3.2 - 3.7 V battery, with a typical capacity of around 30-40 mAh, but can be recharged 300-500 times, with some brands claiming 1000+ charging/recharging cycles.
Lithium non-rechargeable CR2032 battery is probably the most popular and the most common button/coin cell battery in use today.
The physical dimensions of the CR2032 battery are (D x H) 20 x 3.2 mm (0.787 x 0.126 inches), a nominal voltage of 3.0 V, a cutoff voltage of 2.0 V, and a typical capacity in the 210-230 mAh range.
CR2032 battery's typical maximum discharge current is ~3 mA with a maximum pulse discharge current of ~15 mA.
Because of its popularity, the CR2032 battery is manufactured by most battery brands and can be found with different labels, including DL2032, E-CR2032, SB-T51, 5004LC, etc.
The most popular rechargeable 20 x 3.2 mm batteries include ML2032, VL2032, and LiR2032 batteries, but these batteries are rarely used for car key fobs.
Note: although the CR2025 battery may fit the CR2032 battery compartment, the CR2025 battery should not be used instead of CR2032 except in some sort of emergency - the CR2025 battery is 0.7 mm thinner and may have issues with contacts. Also, it has a smaller capacity.
Also, don't put the CR2032 battery in the CR2025 battery compartment - this 0.7 mm height difference doesn't sound much, but it is enough to deform some battery compartments.
Lithium non-rechargeable CR2450 battery is one of the largest and most powerful button/coin cell batteries with a large capacity and is often used in 'high' drain devices, including car key fobs.
CR2450 battery features physical dimensions of (D x H) 24.5 x 5.0 mm (~0.964 inches x 0.197 inches) and a nominal capacity of around 600-620 mAh, which is a significantly higher capacity than, for example, the CR2032 battery.
Note: CR2577 features even higher capacity!
Other common labels for CR2450 include 5029LC, DL2450, ECR2450, CR2450N, CR-2450, CR2450EL, CR-2450EL, etc.
The most common rechargeable 24.5 x 5.0 mm battery is a LiR2450 battery, which has a nominal capacity of 100-125 mAh but is rarely used in car key fobs.
How to Replace the Car Key Fob Battery
The easiest way and also the recommended way of replacing the car key fob battery is to go to the car dealership and ask them to replace the battery for You. Seriously.
Batteries themselves are relatively cheap, and they will probably charge You additionally for their service. But, the task will be done by trained/certified personnel, and You will even get some warranty for the service You are paying.
If that is not the option, find your car's Owner's Guide and check how to replace the car key fob battery.
This is very important since some cars require their key fobs to be synchronized with the car (reset, reprogrammed) itself - this is commonly done by opening the car with the key, inserting the key in the lock, turning the key halfway to the ignition/cranking point and keeping the key in such position for at least half a second.
Obviously, different cars may have different procedures.
However, some cars don't require the user to reset or synchronize the key fob with the car after battery replacement. In that case, to replace the battery, do the following:
- using a thin flat-head screwdriver, gently and carefully open the key fob,
- locate the battery and, if required, take a photo of the key fob internals,
- write down the exact battery model, for example, CR2032,
- replace the old battery with the new one - just be sure to use a battery of the same size and chemistry,
- close the key fob and test it.
Note: You would be surprised how taking photos of various steps during tasks like this one can be helpful ...
And that's it - the key fob battery is replaced.
Modern cars often come with key fobs featuring several buttons that have to be programmed individually - if You have the car Owner's Guide, the programming procedure is described in detail. If it is not listed, and You have to program the key fob, the best course of action is to take the key fob to the car's dealership.
Car Key Fob Battery Frequently Asked Questions (FAQ)
Here are some of the most common Frequently Asked Questions (FAQ) about car key fob batteries:
How do you replace the battery in a key fob?
The replacement procedure is rather simple - open the key fob using a suitable flat-head screwdriver, locate the battery and replace it with a new one and close the key fob.
If the key fob must be reset or reprogrammed, do as stated in the Owner's Guide.
What kind of batteries do key fobs take?
Most key fobs accept lithium button/coin cell batteries, with CR2032 and CR2025 being the most popular ones, although other batteries may be used as well.
How much does it cost to replace a fob battery?
The most expensive button/coin cells cost a few dollars/euros at most. If You are replacing the battery yourself, that is the only cost for You - don't forget that some modern cars require the key fob to be reset or synchronized with the car.
When the fob battery is replaced at the car's dealership, they will charge You both the battery and their service.
Will a dead key fob cause a car not to start?
Generally, no. But You will have to open the car and crank the engine manually.
Do you have to reprogram/reset a key fob after changing the battery?
Yes, but not all.
How much does it cost to replace the key fob battery?
The battery itself usually costs a few dollars/euros at most.
If the battery is being replaced at the car's dealership, they will charge You both the battery and their service, which is still cheaper than a new car key fob.
Can key fob batteries be replaced?
Yes, most car key fob batteries may be replaced.
What happens when the key fob battery is low?
When the key fob battery is almost fully discharged, the battery loses its ability to provide a pulse current strong enough for the key fob's normal operation, resulting in a shorter key fob range.
How do I know what battery my key fob needs?
Check the documentation or open the key fob and check the battery.
How much does it cost for a new key fob?
It varies from brand to brand, but usually much more than the battery itself.
Does it matter what battery I put in my key fob?
Of course - You will not put gasoline in diesel cars and vice versa, right? The same goes with key fobs - check the size and type of the old battery, and when replacing, use the same battery size/type.
Few Final Words
Weak key fob battery can be a rather annoying issue, but it can be solved easily:
- take the key fob to the dealership and ask them to replace the battery for You (and they will also do other tasks if required), or
- replace the key fob battery at home, and if necessary, reset/reprogram/sync the key fob after replacing the battery.
Most car key fobs use CR2025 and CR2032 batteries, but other battery sizes are also used.
Note: Whatever You do, it is your own responsibility ...