What Is A Button Battery?
The Ultimate Guide (2026 Edition)
Table of Contents
Quick Answer
A button battery, also called a coin cell battery, is a small, round battery designed to provide stable, low-power energy for compact electronic devices.
It is commonly used in watches, hearing aids, calculators, key fobs, and medical sensors, with typical chemistries including lithium, silver oxide, and alkaline.
Button batteries are non-rechargeable in most cases and are identified by standardized size and voltage codes such as CR2032 or SR626.
Chemistry
Button battery types differ mainly by chemistry, voltage, and rechargeability: Zn-MnO2 and Zn-Ag2O (silver oxide) are non-rechargeable, with silver oxide offering more stable voltage for watches.
Li-MnO2 (lithium coin cells) provide higher energy density and long shelf life, while Zn-O2 (zinc-air) batteries use oxygen from air and are common in hearing aids.
Rechargeable button cells include Ni-MH (1.2 V), LIR (lithium-ion), ML (rechargeable lithium-manganese), and VL (rechargeable vanadium-lithium), each requiring compatible charging circuits and not interchangeable with primary cells.
Zn-MnO2 Battery
Zn-MnO2 button batteries include both carbon-zinc (Zn-C) and alkaline types, each using zinc and manganese dioxide but with different electrolytes.
Carbon-zinc models (often marked AG or older codes) have lower capacity and shorter shelf life, while alkaline models (marked LR, such as LR44 or LR41) offer higher energy density and better leak resistance.
Different Zn-MnO2 models vary by size and construction, and they are not interchangeable unless the dimensions, voltage, and chemistry match the device requirements.
What does LR44 mean?
LR44 is a standard designation for a 1.5-volt alkaline button battery, where “L” indicates alkaline chemistry and “R” refers to its round shape.
The number 44 identifies the battery’s specific size and dimensions under IEC standards.
LR44 batteries are commonly used in small electronics such as toys, calculators, thermometers, and laser pointers.
Zn-O2 Battery
Zn-O₂ (zinc-air) button batteries generate power by oxidizing zinc while using oxygen from the surrounding air as the cathode reactant.
Different models (such as size 10, 13, 312, and 675) are defined by standardized diameters and thicknesses, which determine capacity and fit in devices.
What are the advantages of zinc-air batteries?
Zinc-air batteries offer very high energy density for their size because they use oxygen from the air rather than storing it internally.
They provide stable voltage output and good performance in low-drain devices such as hearing aids.
Zinc-air batteries are also mercury-free and use abundant materials, making them relatively environmentally friendly.
What are the disadvantages of zinc air battery?
Zinc-air batteries begin to discharge as soon as their sealing tab is removed, which limits usable life once activated.
They have poor performance in high-drain devices and are sensitive to humidity and temperature extremes.
Because they rely on air access, zinc-air batteries also require open battery compartments and have limited long-term storage after activation.
Zn-Ag2O Battery
Zn-Ag2O (silver oxide) button batteries use zinc and silver oxide chemistry to deliver a stable nominal voltage of about 1.55 V.
Different models (such as SR41, SR44, and SR626) vary mainly in diameter and thickness, which determines capacity and device compatibility.
What are the disadvantages of zinc batteries?
Zinc-based batteries generally have lower energy density than lithium batteries, resulting in shorter runtime for the same size.
They are more prone to leakage and corrosion over time, especially in alkaline and carbon-zinc designs.
Zinc batteries also perform poorly at high discharge rates and extreme temperatures, limiting their use in high-drain devices.
What are zinc batteries good for?
Zinc batteries are well suited for low- to moderate-drain devices that require stable voltage and cost-effective power.
They are commonly used in remote controls, clocks, toys, hearing aids, and small medical or household electronics.
Their good shelf availability, safety profile, and recyclability make zinc batteries practical for everyday consumer applications.
Li-MnO2 Battery
Li-MnO2 batteries are primary lithium coin cells that use lithium metal and manganese dioxide, delivering a stable nominal voltage of 3.0 V.
Different models (such as CR2032, CR2025, and CR2450) share the same chemistry but vary in diameter and thickness, which directly affects capacity and device fit.
What are the disadvantages of lithium manganese dioxide batteries?
Lithium manganese dioxide (Li-MnO₂) batteries are non-rechargeable, which limits their use to single-use applications.
They have relatively low maximum discharge current and can show reduced performance at very high or very low temperatures.
Improper handling, crushing, or short-circuiting can create safety risks due to the reactive lithium metal anode.
What does CR2032 mean?
CR2032 is a standardized code for a lithium coin cell battery, where “CR” indicates lithium manganese dioxide chemistry with a nominal 3-volt output.
The numbers 20 and 32 represent the battery’s physical size: 20 mm in diameter and 3.2 mm in thickness.
This labeling system helps ensure correct fit, voltage compatibility, and safe replacement across devices.
Button Battery Performance
Button battery performance is defined by voltage stability, capacity, discharge rate, and shelf life under specific load conditions.
Lithium and silver oxide button batteries offer more stable voltage and longer runtime, while alkaline and zinc-based types are better suited for low-drain use.
Temperature, storage conditions, and correct device matching strongly affect real-world button battery performance.
Do button batteries last longer?
Button batteries can last a long time in low-drain devices because they are designed to deliver small, steady currents over extended periods.
Lithium and silver oxide button batteries typically offer longer service life and better voltage stability than alkaline types.
Actual lifespan depends on the device’s power demand, battery chemistry, storage conditions, and operating temperature.
How to test button batteries?
Button batteries can be tested by measuring their voltage with a digital multimeter set to DC volts.
Compare the reading to the battery’s rated voltage (such as 3.0 V for a CR2032), as a drop of about 10–20% usually indicates significant capacity loss.
For more accurate results, test under a small load, since a no-load voltage may appear normal even when the battery is near failure.
How to insert button batteries?
To insert a button battery, first check the device’s polarity markings and match the battery’s positive (+) and negative (–) sides correctly.
Place the battery flat into the compartment without forcing it, ensuring full contact with the terminals.
After closing the cover securely, test the device to confirm proper operation and avoid loose installation.
Safety - Use Safely
Are lithium button batteries fire hazards?
Lithium button batteries can be fire hazards if they are short-circuited, crushed, overheated, or improperly disposed of.
When the terminals contact metal objects, they can rapidly overheat and potentially ignite nearby materials.
Proper storage, taping the terminals before disposal, and keeping them away from children significantly reduce fire and safety risks.
How to store button batteries?
Button batteries should be stored in a cool, dry place away from heat, moisture, and direct sunlight.
Keep them in their original packaging or in a non-conductive container, with terminals covered to prevent short circuits.
Store button batteries out of reach of children and pets, as accidental ingestion poses serious safety risks.
How long after swallowing a button battery do symptoms show?
Symptoms after swallowing a button battery can begin within 2 hours, even before obvious pain or distress appears.
Serious internal injury is caused by electrical current and chemical reactions, so damage may occur rapidly while early symptoms remain mild or nonspecific.
Because of this delayed presentation, any suspected button battery ingestion is a medical emergency requiring immediate evaluation, even if symptoms are not yet visible.
How to dispose of button batteries?
Button batteries should be disposed of at designated battery recycling centers or household hazardous waste collection points, not in regular trash.
Before disposal, tape over the battery terminals to prevent short circuits and reduce fire risk during transport.
If no local recycling option is available, follow your municipality’s hazardous waste guidelines, as button batteries contain metals that can harm the environment.
Button Cell Applications
What has button batteries?
Button batteries are used in many small electronic devices that require compact, low-power energy.
Common examples include watches, hearing aids, key fobs, calculators, toys, remote controls, medical devices, and LED lights.
They are also found in everyday items such as digital thermometers, bathroom scales, and some greeting cards.
How do I tell what button battery I need?
To determine which button battery you need, check the device manual or open the battery compartment to find the printed battery code, such as CR2032 or SR626.
If the code is not visible, measure the battery’s diameter, thickness, and voltage to match standard button battery sizes.
Using the correct chemistry and voltage is critical, as visually similar button batteries are not always interchangeable.
Frequently Asked Questions
Some button batteries are lithium-based (such as CR series lithium coin cells), but many button batteries are non-lithium types like alkaline or silver oxide, so “button battery” refers to the shape, not the chemistry.
Yes, rechargeable button batteries exist—most commonly lithium-ion or nickel-metal hydride coin cells—but they have lower capacity than disposable button batteries and require a compatible charger and device support.
Toys that commonly use button batteries include small electronic toys such as light-up toys, talking dolls, musical books, remote-control key toys, laser pointers, fidget toys with LEDs, and novelty toys where compact size requires coin cell batteries.
Button batteries are dangerous because when swallowed or inserted into the body they can generate an electrical current that rapidly causes chemical burns and severe internal tissue damage, especially in the esophagus, within a short time.
Swallowing a button battery is a medical emergency because it can lodge in the esophagus and cause severe chemical burns, tissue damage, or life-threatening complications within hours, requiring immediate emergency care.
You can identify a button battery size by reading the engraved code on the cell (such as CR2032 or LR44), which specifies its diameter and thickness, or by measuring the battery with a caliper and matching the dimensions to standard coin cell charts.
A zinc battery is not inherently better than a lithium battery, as zinc batteries typically offer lower energy density and shorter runtime but improved safety and lower cost, while lithium batteries provide higher performance and longer life for most electronics.
You can tell if a CR2032 battery is good or bad by measuring its voltage with a multimeter—around 3.0 V indicates a healthy battery, while readings below about 2.7 V usually mean it should be replaced.
The longest life of a CR2032 battery is typically up to about 10 years of shelf life under proper storage, while actual service life in a device ranges from months to several years depending on current draw and usage.
