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Do Unused Batteries Expire? A Complete Beginner’s Guide

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It’s always useful to have a couple of spare batteries tucked away. However, you might not need to call on your emergency stash of batteries for a long time, especially if your go-to batteries are rechargeable.

It’s worth considering if your spare batteries have a shelf life, and if so how long can you expect them to hold their charge until they become unusable. Several factors affect a battery’s ability to hold its charge, most notably where the batteries are stored. 

A battery’s composition (what it is made out of) can also have a significant impact on its ability to hold a charge and in turn, its ability to expel this charge to power a device. We will be outlining the various types of batteries you can buy and how long they typically last.

There is also a big difference between rechargeable and non-rechargeable in terms of lifespan and composition that is worth noting. 

The short answer to the question posed by this article is, yes, unused batteries do expire. However, there are numerous types of rechargeable and non-rechargeable batteries and each of these types has a range of shelf lives. 

Best if Used By (BIUB) Explained

Do Unused Batteries

Like food and other consumables, all batteries have an expiration date. Typically, this date is printed on the battery sleeve, usually at the top near the battery type (AA, AAA, 9V for example).

The Best if Used By is usually printed in year format, as nearly all batteries can be left unused for one year at a minimum. If you have smaller batteries that simply aren’t large enough to accommodate the BIUB, they can be found on the packaging. 

Best if Used By Dates on batteries are an estimate of when the battery will have 80% charge left, relative to the date of manufacture.

What’s Inside a Battery?

Seven components make up a household battery, these are cathode, anode, container, separator, electrolyte, electrode, and collector.

Each of these components has a specific job within the battery. We have included a summary of each of these components below:

  • Cathode: A mixture of manganese dioxide and carbon, the cathode is the electrode that is reduced by the electrochemical reaction. 
  • Container: The Container is the steel housing around the rest of the components. It forms part of the electrochemical reaction.
  • Collector: A brass pin housed at the center of the battery that conducts electricity to the circuit.
  • Separator: Usually a non-woven fabric designed to separate the electrodes 
  • Anode: Composed of powdered zinc metal, anodes are electrodes that are oxidized
  • Electrolyte: A Potassium Hydroxide solution suspended in water, the electrolyte is the vehicle that transports ions within the battery and carries the iconic current. 

The average household alkaline battery is made of steel and a mixture of zinc/manganese/graphite/potassium with the rest of the battery comprising of paper and plastic. 

How Do Batteries Work?

Batteries are tiny power plants that change chemical reactions to electrical energy. When you insert a battery into any device you are completing the circuit of the device and starting the chemical reaction. 

When the device powers on the electrolyte oxides the anode’s powered zinc. Once this has happened the manganese dioxide/carbon mix in the cathode reacts to the oxidized zinc and generates electricity. 

Over time the interactions between the zinc and electrolyte produce bi-products that slow the battery action and reduce its voltage. 

How Long Do Unused Batteries Last?

A battery’s charge integrity (how much of the charge it holds) starts to decrease from the moment the battery is made. That being said, the process of a battery losing its charge happens over a long period. In some cases and types of battery, it can spend years unused before a significant difference is noticeable. 

There is no straight answer to the question of how long do batteries last. That’s because many factors influence a battery’s lifespan including the run time, charge/discharge cycle, and shelf life. All of which are also dependent on the type of battery in question. 

For an unused battery to go past its expiration year doesn’t necessarily mean that the battery is unusable. There is a clear difference between an expired battery and a battery that has gone bad and become unusable.

A battery past its expiration date that hasn’t gone bad means that it shouldn’t be expected to have a full life anymore. 

In simple terms, a battery that has gone bad usually means that the battery has corroded. This is sometimes visible as the contents can leak out of the battery. This is commonly known as “battery acid” and it’s pretty nasty stuff. In household batteries, the “acid” is alkaline.

The alkaline in batteries is highly corrosive and when mishandled can cause skin burns, contaminate soil, or even render whatever device they’ve leaked into useless. 

Non-Rechargeable Battery Types

As the name suggests, non-rechargeable batteries are not designed for multiple charges and discharge cycles, meaning that once the battery has expelled its charge, it needs to be changed. 

Alkaline Batteries

These are the most common type of non-rechargeable batteries and are widely available. Depending on how these batteries are stored (more on this further down the article) they have a shelf life of between five to ten years. 

Carbon-Zinc Batteries

Typically cheaper than alkaline batteries however they have a shorter shelf life. Carbon-zinc batteries are more prone to leaking as they have thinner walls than other batteries. Their shelf life is usually between three to five years. 

Lithium Non-rechargeable batteries

These batteries have the longest lifespan of most non-rechargeable batteries at ten to twelve years. There are, however, a few factors that can influence this longevity like a particular brand’s manufacturing process or their chemical makeup. 

Rechargeable Battery Types

Just as there are many types of Non-Rechargeable Batteries, there are numerous Rechargeable Battery compositions. These each have their advantages and disadvantages, based on many factors. 

Lithium Rechargeable Batteries

There are a variety of lithium batteries available, each type can be made up of various chemical compounds including lithium. Lithium rechargeable batteries tend to last for between 700 and 1,000 charge cycles and have a shelf life of three to five years.

Nickel-Cadmium Batteries

Nickel-Cadmium batteries are some of the oldest types of rechargeable batteries. There are numerous advantages to these batteries, namely a longer shelf life and charge/discharge cycle life.

Unlike other batteries, they also retain their performance quality when subjected to extreme temperatures. The shelf life of these batteries is usually between eighteen to thirty-six months. 

Nickel Metal Hydride Batteries

Whilst typically having a longer shelf life than Nickel-Cadium batteries, Nickel Metal Hydride batteries have shorter charge cycle lives. They also have a higher energy density which means that they don’t need to be charged as often.

Typically, they have a shelf life of three to five years much like Lithium rechargeable batteries. 

Lead-Acid Batteries

There are numerous kinds of Lead-Acid batteries and these can vary in terms of performance, charge cycles, and shelf life. On average, a lead-acid battery’s shelf life is around six months. 

How to Take Care of Rechargeable Batteries?

Rechargeable batteries are becoming increasingly popular and more common, particularly lithium-ion batteries. With the development of electric cars and other materials, battery technology has come on leaps and bounds.

That being said, it is still important to be aware of the best ways to take care of your rechargeable batteries and maximize their lifespan.

If you are not going to use your rechargeable batteries for a long time, longer than you usually would leave them, store the battery with at least a 40% charge. As we talked about earlier in the article, all batteries slowly discharge regardless of being in use or not.

Storing the battery at 40% means that the battery can slowly discharge so that it can be recharged when you need it. 

It is also important to allow your rechargeable batteries to reach their full charge before using them. Most rechargeable batteries, especially lithium-ion batteries “like” to be charged.

It’s also important to remember that all rechargeable batteries have a charge/discharge life cycle and as such taking the battery on and off the charger more often than necessary reduces this life cycle.

Remember also that taking the battery off the charger as soon as it’s charged helps to preserve the battery’s life span.  

The Memory Effect

Some of the older rechargeable battery compositions, particularly nickel-cadmium and nickel-metal hydride can suffer from what is known as The Memory Effect.

Also known as the battery effect, battery memory, or lazy battery effect, The Memory Effect is an observable issue with these batteries. It’s useful to be aware of The Memory Effect, as it is a common issue with the types of batteries named above. 

In simple terms, The Memory Effect causes these types of batteries to hold less charge. If these batteries are charged after only being partially discharged, the battery seems to remember the smaller capacity. 

There are a few things to bear in mind when we talk about The Memory Effect. Whilst it is an observable effect, other problems with the battery can be perceived as the memory effect.

We’ve outlined some of the most common issues which batteries which can seem like The Memory Effect: 

Voltage Depression Due to Long-Term Over-Charging

Have you ever noticed that the battery in your digital camera or cell phone drops significantly, even sometimes when not in use? These devices are known as “high-load” devices, meaning the battery has to supply large amounts of current to power the device.

The most common cause of voltage depression is repeatedly over-charging the battery. This is becoming a common problem as consumer “trickle chargers” often overcharge. 

Extreme Temperatures

As we discuss further down this article, exposure to extreme temperatures can affect all types of batteries. Due to the chemical reactions happening inside of a battery, any exposure to extreme temperatures can affect the rate of these chemical reactions.

For example, higher temperatures can reduce the overall charged voltage of a battery and the capacity of the cells to accept a charge. 

Storing Batteries to Maximize Their Lifespan

Do Unused Batteries Expire1

As mentioned above, the conditions in which batteries are stored play an important role in their longevity. It is a common misconception that you should store batteries in the fridge or freezer, and nothing could be further from the truth.

If the battery is stored in an environment that is excessively hot or cold this will have serious implications. Not only on the battery’s dormant life span but also its potential to leak corrosive chemicals. 

However, there are some steps you can take to ensure that your batteries last you as long as possible:

  1. Take them out of devices when not in use: This is something that seems like common sense. Batteries taken out of the devices they power will last longer. It also means that if the batteries did corrode and leak, the device would not be damaged. 
  2. Don’t mix old and new batteries: This is a classic mistake to make, especially if you only have one new battery. By mixing old and new batteries you are increasing the risk of battery leakage. As mentioned above, this is something that you need to avoid to preserve the device. 
  3. Avoid exposure to extreme temperatures: The temperature you store batteries at makes a huge difference. As the batteries have highly sensitive chemicals in them it is not advisable to leave them in a hot or cold place. Storing them in a cool, dark, and dry place is the best way to preserve batteries.
  4. Keep them away from other metal objects: The easiest way to do this is to keep them in their original packaging. When batteries come in contact with metal objects they run the risk of leaking or rupturing. 

Useful Tips

Below are some useful tips and hints to bear in mind when handling and using batteries: 

  • Ensure you’re pairing the right batteries with the right device: this doesn’t just apply to using the correct size batteries in any given device(AAA or AA for example). Batteries have a specific discharge rate. Using a battery not designed for a higher discharge rate can affect its lifespan. 
  • Always fully charge your batteries: taking batteries off the charger prematurely can also affect the charge/discharge life cycle.
  • Never try to recharge single-use batteries: This may seem like common sense but it is worth mentioning. Attempting to recharge single-use batteries can cause these batteries to overheat and even explode. 
  • Recycle where possible: all modern batteries can be recycled. This is beneficial for many reasons but mainly because by recycling your batteries you prevent them from going to landfills and potentially leaking into the soil.

Frequently Asked Questions

Whilst this list of FAQ’s is not exhaustive, we hope it covers all of your questions:

Can I Mix Old Batteries With New Batteries? 

In short, no, this isn’t advisable as it can cause battery leakage which damages devices.

I Heard That You Should Keep Batteries In The Fridge, Is This True?

Unless you live in an extremely hot country, you should not store batteries in the fridge

My Battery Has Gone Past Its BIUB Date, But Only By A Few Months, Can I Still Use It? 

Absolutely! Even though the battery has gone past its Best if Used by Date it will still be viable – provided it has been stored correctly. 

My Battery Seems To Be Seeping Out A Blue-Tinted Metallic Fluid – What Is This?

When a battery is heavily corroded it will rupture and start to leak a highly corrosive mix of chemicals. When this happens the battery is useless and must be disposed of properly. 

Can I Recharge Single-Use Batteries?

This one seems like a no-brainer, you can only recharge batteries that are designed to be recharged.

My Rechargeable Battery Doesn’t Seem To Last As Long As Before, Why Is This? 

If the battery in question is nickel-metal hydride or nickel-cadmium based then the battery may have something called The Memory Effect (see our handy section on this above).

Is it OK To Mix Different Brands Of Batteries? 

In short, no, it’s best to use the same brand of batteries in any device. This is because voltage and chemical composition vary from battery to battery and brand. 

Are Batteries Recyclable? 

It is definitely a good idea to recycle batteries. Usually, a waste disposable site will have a section dedicated to batteries. Nearly all batteries are recyclable but this should be done properly. 

Summing Up

There are a few key takeaways from this article:

  1. Batteries do expire – however, a battery that has gone past its Best if Used By Date may still be viable. 
  2. Numerous factors influence a battery’s lifespan including the type of battery, the charge/discharge rate, and the temperature they’re stored at.
    • When not in use, rechargeable batteries should be stored with roughly 40% charge to preserve their lifespan.

It can be easy to miss many of the things in this article, simply because we don’t often think about batteries in general.

They have become such an easy and accessible commodity that it’s easy to overlook the importance of battery safety.

That being said, understanding batteries and how to care for them will help you get the most out of them and prevent them from being wasted.