Button cell batteries are small round-shaped batteries less than 25 mm in diameter and less than 5 mm in height. Several types of batteries have different chemical compositions, but they are mainly divided into four classes.
- Alkaline
- Lithium
- Silver Oxide
- Zinc-Air
The button cell batteries are used in watches, clocks, calculators, remote controls, keyless entry systems, medical devices, hearing aids, etc.
The most common voltage ratings are 1.5V, 3.0V, and 3.6V. Towards the end of the battery’s life span, it will not produce the intended voltage, and batteries should be tested for the correct voltage. This article is on how to test button batteries.
What are Button Batteries?
 As the name suggests, this battery resembles a button or a coin. Though small, a battery can last up to a couple of months to a couple of years.
There are wristwatches with guaranteed 10-year batteries. The most common voltage ratings for these batteries are 1.5 V, 3 V, and 3.6 V. Depending on the specific applications, There could be different voltage ratings.
There are many different battery types depending on the chemical composition. The most common are the Alkaline, Lithium, Silver Oxide, and Zinc-Air. These types have other performance characteristics.
How to Test Button Batteries?
Though there are a few methods to check a button battery, the correct way is by using a multimeter. Before testing the battery, there are a few things one should know about the battery. The first one is the battery voltage, and the other is the positive and negative sides of the battery. Usually, all this information is printed on the battery.
Most button batteries come with a voltage of 1.5 to 3.0, and it will be printed on the battery. With time, when the battery is used, it will no longer give the required voltage. At this point, it is called a drained battery.
To check a battery with a multimeter, it should be set up to read DC voltage. By placing the multimeter in red and black leads to the battery’s plus and minus sides, its correct voltage can be determined.
This method of testing a battery is called initial testing, and there is a more accurate way of testing a battery called a load test. The load test simulates the actual conditions under which the battery will be used.
A minimal voltage drop is considered to cause the battery to be drained. The table below shows the common battery types with their initial voltages and the voltage the battery needs replacing.
| Battery Type and initial voltage | Battery Replacing Voltage |
| Lithium – 3.0 V | 2.8V |
| Silver Oxide – 1.5 V | 1.2V |
| Alkaline – 1.5 V | 1.0V |
Why is it Important to Test Button Batteries?
The button or the coin batteries are used in most appliances that need batteries because of their small size, durability, and low price. These appliances may include health equipment used to save lives and remotes to door locks where people will be locked out.
Key Fobs that control vehicles, wristwatches, etc. These button batteries play a significant role in everybody’s life.
Some appliances that use these batteries play a critical role in medical equipment. Replacing the batteries before they are drained is essential, and testing is the only method to know whether it is required to replace them before draining.
Can you Test Button Batteries without a Multimeter?
There are few methods by which a battery can be tested without a multimeter. A battery tester is another way to read the battery condition accurately. A battery tester can be considered a multimeter specially built to check batteries. These testers can test a variety of batteries, including button batteries.
Apart from a multimeter and a battery tester, some unconventional methods exist to check batteries. All these methods only show that the battery has some power and do not give an accurate voltage or indicate whether the battery needs to be replaced.
- Using a light bulb is a simple way to test a button battery. Connecting a bulb with a similar voltage to the battery can give an idea of its condition. If the bulb lights up, it means the battery has some power.
- Fixing the battery to its original appliance or a similar one is another way to check a battery. If the device is not working, the battery has an issue.
What do the Readings mean When Testing Button Batteries?
The multimeter gives the voltage difference between the positive and negative poles of the button cell battery. No matter how hard they look inside, some chemicals produce electricity.
A 3-voltage battery will produce 3 V current for a certain period. With time, when the substances fade away, the battery will no longer be able to maintain the 3 V difference in its poles.
At this point, the button cell will still produce a current but not a 3V current. The reading at the latter part of its life cycle will show a lesser voltage than the marked one.
When a battery comes to this stage, it will drain away faster than when it gave the correct voltage.
How Do I Know If My Button Cell Battery is Good?
If the device the battery is fitted is working correctly, it signals that it is still good. However, the battery’s life should be considered when using such a device, as there is a good chance of suddenly dying due to the drained battery.
Most of the equipment runs on a set voltage range, and the button cell battery will hold the necessary voltage for a specific time.
During the latter part of the button cell battery’s life cycle, it will no longer be able to give the intended voltage, making the device it powers to fail. This will be a good sign to know that the button cell battery is not in good condition.
Do Button Batteries Expire?
Yes, button cell batteries expire, which can happen in 2 ways. A button cell battery can pass when its useful life span is over, and the batteries are not made to recharge.
A button cell battery, called the shelf life, will expire even if not used. The shelf life of a button battery depends on the battery type. Humidity and extreme temperatures are the main reasons for the batteries to expire.
Once the battery has expired, chemicals can leak, which could be dangerous to the environment and the user.
Different battery types leak other chemicals, which can damage the devices they are fixed, and some of these batteries are highly flammable. Â
What is the Lifespan of a Button Battery?
The lifespan of the button cell battery depends on the equipment used and its usage. The batteries of a simple watch will last longer than a car fob with remote facilities using the same kind of batteries.
Usually, the equipment manufacturers give the correct battery type and the lifespan of the batteries. Usually, the life span of a battery in a watch will be up to 10 years, and a car fob will have up to 3-5 years.
The shelf life of a button cell battery will depend on the battery type. A Lithium battery has a shelf life of 10 years, alkaline five years, lithium-ion three years, silver oxide three years, and zinc two years.
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Video Credits – Darssan & Havish
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