Battery Wisdom

Battery Wisdom

Learn how to choose, use, charge, store, and replace batteries safely. Explore battery types, sizes, voltages, equivalents, terminals, chargers, and common applications.

Not sure which battery you need? Use the guides below to identify the correct battery and understand how it works.
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Explore Battery Topics

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Find the Right Battery

Learn how to identify voltage, size, chemistry, terminals, and replacement numbers.

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Battery Types

Understand alkaline, lithium, lithium-ion, NiMH, NiCd, LiFePO4, silver oxide, and more.

Explore Battery Types →
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Charging & Battery Life

Learn about chargers, capacity, mAh, charge cycles, runtime, and proper charging.

Learn About Charging →
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Safety & Care

Learn how to store, handle, charge, and dispose of batteries safely.

View Safety Information →
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Common Applications

Find battery information for watches, flashlights, hearing aids, security systems, medical devices, and more.

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Battery Equivalents

Understand replacement numbers, cross-references, brand equivalents, and compatible battery sizes.

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Battery Size & Replacement Charts

Use our battery charts to compare battery numbers, voltage, physical dimensions, chemistry, and common replacement numbers. Always confirm the required battery specifications before ordering.

View Complete Battery Charts
CR

CR Lithium Batteries

Compare CR coin-cell sizes, voltage, dimensions, and common replacement numbers.

View CR Lithium Chart →
377

Button Cell Batteries

Compare alkaline and silver-oxide button-cell numbers and physical sizes.

View Button Cell Chart →
312

Hearing Aid Batteries

Review the common Size 10, 13, 312, and 675 hearing-aid battery references.

View Hearing Aid Chart →
A23

Specialty Batteries

Find dimensions and replacement numbers for CR123A, CR2, A23, A27, 2CR5, and other specialty batteries.

View Specialty Chart →
18650

Assembly Battery Sizes

Compare common cylindrical cell sizes, chemistries, voltages, and physical dimensions.

View Assembly Chart →
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View All Battery Charts

Open the complete reference page to search all available battery sizes and equivalents.

Open Battery Charts

Quick Coin-Cell Size Example

Coin-cell numbers often describe the approximate diameter and thickness. The batteries below are all 20 mm in diameter but have different thicknesses.

Battery Voltage Approximate Size Main Difference
CR2016 3 Volt 20 × 1.6 mm Thinnest of the three
CR2025 3 Volt 20 × 2.5 mm Medium thickness
CR2032 3 Volt 20 × 3.2 mm Thickest of the three
Important: A similar battery number or physical size does not always mean two batteries are interchangeable. Confirm the voltage, chemistry, dimensions, terminal style, and device-manufacturer requirements before replacing a battery.

Identify Your Battery

Battery shape, terminal style, markings, and connector type can help you identify the correct replacement. Compare your existing battery with the examples below before ordering.

FLAT TOP
BUTTON TOP

Flat Top vs. Button Top

Flat-top batteries have a level positive terminal. Button-top batteries have a raised positive contact. The wrong top style may not make proper contact inside your device.

Learn More →
F1
0.187"
F2
0.250"
F3
BOLT

F1, F2 & F3 Terminals

Sealed lead-acid batteries may use narrow F1 tabs, wider F2 tabs, or bolt-style F3 terminals. Confirm the terminal dimensions and orientation before replacing the battery.

Compare Terminals →
TABS
WIRES

Tabs, Wires & Connectors

Some batteries include solder tabs, wires, plugs, or custom connectors. Match the connector shape, wire colors, polarity, and wire position exactly.

View Connector Information →
CR2032
3V
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Coin-Cell Markings

Read the full number printed on the battery. Letters can identify the chemistry, while the numbers often relate to the battery’s diameter and thickness.

Check the Battery Charts →
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PROTECTED
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UNPROTECTED

Protected vs. Unprotected

Protected lithium-ion cells include added electronic protection and may be slightly longer. Use only the battery type specified by the device manufacturer.

Learn About Protection →
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Positive & Negative Polarity

Check the positive and negative markings before installation. Reversed polarity may prevent the device from operating and may damage the battery or equipment.

View Battery Safety →

Before Ordering a Replacement Battery

✓ Read the complete battery number or model number.
✓ Confirm the voltage and battery chemistry.
✓ Measure the battery’s length, width, height, or diameter.		 ✓ Check the terminal, tab, wire, or connector style.
✓ Confirm positive and negative polarity.
✓ Review the device manufacturer’s battery requirements.
Still unable to identify your battery? Take clear photos of the battery label, terminals, connector, and device model number. Send them to sales@onlybatteries.com or call (800) 660-7705 .

Frequently Asked Questions

Find quick answers to common questions about battery replacement, capacity, voltage, chemistry, charging, and compatibility.

Can I use a battery with a higher mAh rating?

A higher mAh rating generally means more capacity and potentially longer runtime. The replacement must still match the required voltage, chemistry, size, terminal style, and device specifications.

Can I replace a 3.2V 18650 battery with a 3.7V 18650?

Usually not. A 3.2V 18650 is commonly LiFePO4, while a 3.6V or 3.7V 18650 is commonly lithium-ion. They use different charging voltages and should only be substituted when the device manufacturer specifically approves it.

Why does my replacement battery not fit?

Batteries with the same basic number can sometimes differ in length, top style, protection circuitry, tabs, plugs, or terminals. Compare the full specifications and physical dimensions before ordering.

Are CR2032 and CR2025 batteries interchangeable?

Both are commonly 3V lithium coin cells with a 20 mm diameter, but the CR2032 is thicker than the CR2025. Use the exact size required by the device to ensure proper fit and contact.

Can I replace a NiCd battery with a NiMH battery?

Sometimes, but not automatically. The voltage, pack configuration, charger, connector, dimensions, and device requirements must all be compatible.

What is the difference between F1 and F2 terminals?

F1 terminals are narrower, while F2 terminals are wider. Even when the battery voltage and capacity match, the wrong terminal size may not connect correctly to the device wiring.

Can I mix old and new batteries?

It is best not to mix old and new batteries. Differences in charge level and condition can reduce performance and may increase the risk of leakage or damage.

Can I recharge a battery that is not marked rechargeable?

No. Do not recharge a battery unless it is clearly identified as rechargeable and you are using a charger designed for that battery chemistry and voltage.

Battery Safety & Care

Follow the battery and device manufacturer’s instructions. Stop using any battery that appears damaged, swollen, leaking, or unusually hot.

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 Use the Correct Charger Use only a charger designed for the battery chemistry, voltage, and configuration.
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 Do Not Mix Batteries Do not mix old and new batteries, different brands, chemistries, voltages, or capacity ratings unless specifically permitted.
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 Check Polarity Install the positive and negative terminals in the direction shown by the device manufacturer.
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 Keep Coin Cells Away from Children Store coin and button batteries securely and keep loose cells out of reach of children and pets.
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 Prevent Short Circuits Do not carry loose batteries with keys, coins, tools, or other metal objects that may contact the terminals.
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 Store Batteries Properly Store batteries in a cool, dry location away from direct sunlight, moisture, heat sources, and conductive materials.
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 Recycle Responsibly Follow applicable local regulations and recycling instructions for the battery chemistry being discarded.
Damaged battery warning: Do not use a battery that is swollen, punctured, leaking, corroded, crushed, unusually hot, or producing an unusual odor. Avoid direct contact with leaking material and follow the manufacturer’s safety instructions.
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Need Help Identifying a Battery?

Our customer service team can help you identify a replacement battery based on the battery number, voltage, dimensions, terminal style, connector, or device model.

For the fastest assistance, send clear photos of the battery label, terminals, connector, and the model number of the device where the battery is installed.

 Email Customer Service Call (800) 660-7705 View Battery Charts
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Contact Customer Service

Phone: (800) 660-7705
Email: sales@onlybatteries.com

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Customer Service Hours

Monday–Friday
8:30 AM–5:30 PM EST
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Information to Include

Battery number, voltage, dimensions, terminal or connector type, device brand, and device model number.

Our Locations

United States Address 35A Smithfield Blvd, Suite 700
Plattsburgh, NY 12901 		Canada Address 8559 Dalton Road
Montreal, QC H4T 1V5
Please note: Product compatibility is based on the information provided. Always verify the voltage, chemistry, dimensions, polarity, connector, terminal type, and device-manufacturer requirements before installing a replacement battery.

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