But, can buying excessive batteries and having them sitting unused be the best option? 

Do CR2032 batteries expire?

Yes, CR2032 batteries do expire. But, unlike food which should be thrown out when it expires, CR2032 batteries can still be used (however it is not advisable).  CR2032 batteries have a shelf life (rather than an expiry date) of around 10 years when stored on the ‘shelf’ and not used. This shelf life normally indicates how much of the capacity the CR2032 will lose over these 10 years, which is on average about 10%. So, a C2032 battery which has not been used for more than 10 years isn’t going to be as effective or useful as a new CR2032 battery. 

Why do CR2032 batteries expire?  

All batteries (including the CR2032) have what is known as a self-discharge rate. Batteries produce voltage due to chemical reactions that occur within them. Even when the battery is not connected there are a small amount of chemical reactions. These small reactions are unwanted and reduce the battery’s capacity over time. This phenomenon is known as a battery’s self-discharge rate. 

The rate at which a battery self-discharges when not used comes down to a number of factors which include chemical composition, state of charge, and ambient temperature. 

The table below highlights the commonly used chemicals for batteries and their corresponding self-discharge rates. 

How long does it take for CR2032 batteries to expire?

Knowing how long it takes before a CR2032 expires, or comes to the end of shelf life depends on its self-discharge rate we just learnt about. This self-discharge rate is dependent on a couple of factors, but the biggest one being the battery’s chemical composition. 

The CR2032’s chemical composition consists of Lithium – Manganese Dioxide. From the table above we can see it has a very low self-discharge rate of 1% per year. This value of 1% per year is achieved when stored at a temperature of 20℃.

If stored in ideal conditions, the CR2032 can last up to 10 years when not being used. After 10 years, the CR2032’s capacity will have reduced due to self-discharge. 

As we know temperature plays a big part too. The hotter temperatures are going to increase the CR2032’s self-discharge rate and reduce its shelf-life. So, ideally you want to store the CR2032 in cooler temperatures to increase its lifespan. 

How long does it take for CR2032 to expire when left in a device?

The scenario we just covered above is when the CR2032 is left unused on the shelf (in its packaging for example). However, what if the battery is left unused in a device? Will it still last 10 years?

In the case of a battery being left in a device unused, its shelf life is reduced compared to if it was left unused in its packaging (or not in device). This is due to what is known as Parasitic Load, which is a phenomenon where an electronic device will still draw power from the battery even after the device is turned off. Due to this, the battery will have reduced lifespan. 

So, the CR2032’s will expire much quicker if it is left unused in electronic devices due to this parasitic load. 

Can you use CR2032 batteries after they expire?

To get the best performance out of the CR23032 (and other batteries), it is best to use it before its expiry date. As mentioned earlier, the CR2032’s capacity reduces over time (due to self-discharge), and using it past its expiry date may result in you not getting the most effective power output from it. 

How to prolong the life of CR2032 batteries

The CR2032 is going to expire sooner or later. However, there are things you can do to ensure that it doesn’t expire faster than it should. 

Firstly, we know that hotter temperatures will increase the CR2032’s self-discharge rate. So, avoid storing it in areas where the ambient temperatures are hotter on average. Also, avoid placing the CR2032 in direct sunlight.

Secondly, if you know you are not going to use a device for a long period of time, remove the CR2032 from the device to avoid the parasitic load shortening its shelf-life.

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