CR2032 Coin Cell Battery Basics

The CR2032 coin cell battery is a flat cylindrical battery commonly used in a bunch of small electronics applications requiring little current draw over long periods of time.

You might have seen them in a wristwatch, personal security alarm, remote control or any piece of wearable electronics.

The CR2032 is easily the most popular coin cell in use. You may have noticed on the motherboard of your computer and digital video recorder. It contains a Lithium Manganese Dioxide chemistry (Li/MnO2) and provides a voltage of 3V.

The numerical part of the battery's name CR2032 comes from the width and height measurements of the battery.

That is the first two digits (20) reflect how wide the battery is in millimeters whereas the last two digits (32) use the height of the battery in10ths of millimeters.

The CR denotes the battery chemistry classification (manganese dioxide and lithium).

Simply put, CR2032 is a coin cell battery or button battery with a diameter of 20mm and a thickness of 3.2mm, hence the name.

Below you can see a datasheet snip of the Energizer CR 2032 Lithium Coin Battery.

Basically, there are three key segments inside a CR2032 battery:

• Anode, made of Li, releases lithium ions when the battery discharges.
• Cathode, that has MnO2, takes in lithium ions when discharging.
• Electrolyte (alkaline or leak-resistant organic), a conductive paste that facilitates the movement of lithium ions between Anode and Cathode.

When you connect a load across the battery terminals, it forms an electrical circuit between the Anode and Cathode, allowing lithium ions to flow. This flow of ions creates a flow of electrons, which generates an electric current that powers the load.

There is no one single reason you would opt for employing a coin-cell battery in a project, however there are a couple of safety-related things to consider (taken from a product datasheet):

• KEEP OUT OF REACH OF CHILDREN: Swallowing coin the battery may lead to serious injury or death in as little as 2 hours due to chemical burns and potential perforation of the esophagus.

• BATTERY COMPARTMENT DESIGN: To prevent children from removing batteries, battery compartments should be designed with either a tool such as screwdriver or coin is required to open battery compartment, or the battery compartment door/cover requires the application of a minimum of two independent and simultaneous movements of the securing mechanism to open by hand. Screws should remain captive with the battery door or cover.

Now see the MAXELL Coin Type CR Battery Safety Datasheet ↗

Finally, a quick note on its ISR (internal series resistance).

In principle, a battery is an ideal voltage source connected to a resistor in series. 

As you draw current (I) from a battery, the voltage drop (V) across the circuit will change according to the internal resistance (Rint) of the battery.

For most batteries, this internal resistance is pretty low but still results in a small voltage drop relative to current drawn.

The CR2032 batteries also have some internal resistance that affects how we use them.

Ideally, a battery’s internal resistance should be 0Ω to ensure maximum current flow without energy 

However, in reality, internal resistance always exists, and it affects the battery’s current-delivering capacity. 

The higher the internal resistance, the greater the energy loss, and this not only results in energy wastage but also contributes to battery degradation.

Deplorably, the internal resistance of a CR2032 battery is quite a bit higher (15Ω-20Ω) than that of a regular AA alkaline cell (0.1Ω-0.9Ω). As the battery depletes ,this resistance increases further.

Note at this point that the internal resistance of a battery does not consist of the cells alone but also includes the interconnection, fuses, wiring and protection circuits if any.

Also, it is  important to keep note that internal resistance is just one of many factors affecting the  performance and lifespan of the battery.

Certain other factors (such as capacity, temperature, and discharge cycle) also play significant roles here.

To sum up, the CR2032 coin type lithium manganese dioxide battery is a small, lightweight battery with an operating voltage of 3V and the ability to operate over a wide temperature range.

It has a wide range of applications for powering low-current devices such as various wearable devices, healthcare equipment, keyless entry systems, communication tags, beacons, data loggers and IoT sensors.

It also provides a stable operating voltage under long-term low load discharge for Memory and RTC (real time clock) backup circuits.

That's all for now. If you've got any more questions about coin cell batteries, start the conversation below.