Battery Sizes for Flashlights: Ultimate Guide

When it comes to flashlights, knowing the right battery size is essential for optimal performance. With a wide range of battery sizes available in the market, choosing the right one for your flashlight can be overwhelming.

While many flashlights use common AAA or AA batteries, various other sizes offer unique advantages. One such alternative is the CR123A battery, also known as the camera battery. These small but powerful lithium batteries pack a punch regarding voltage and energy output.

This flashlight battery size guide will explore some of the most common flashlight battery sizes and their advantages. So, continue reading to know the battery sizes for flashlights and which one is best for you.

Types of Batteries for Flashlights

The world of flashlights is diverse, filled with various batteries that power these handy devices. Here are the most common types of batteries used in flashlights.

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1. Alkaline Battery

One popular type is the alkaline battery, known for its reliable performance and widespread availability. Alkaline batteries are affordable and long-lasting, making them a go-to choice for many flashlight users.

2. Lithium-ion Battery

Lithium-ion batteries might be the way to go if you’re seeking even more power and durability. These rechargeable options pack a punch in terms of energy density and have a longer lifespan than their alkaline counterparts.

While they may be pricier upfront, the cost-saving benefits over time make lithium-ion batteries an attractive option for avid flashlight enthusiasts.

3. Nickel-metal Hydride (NiMH) Battery

For those who prioritize eco-friendliness, rechargeable nickel-metal hydride (NiMH) batteries are worth considering. These energy-efficient alternatives reduce waste and provide excellent performance in high-drain devices like flashlights.

NiMH batteries can be recharged hundreds of times before losing capacity and offer extended use time per charge compared to traditional alkaline batteries. Their lower self-discharge rate means they can hold their charge longer when not in use.

4. Alkaline Battery Sizes for Flashlight

Alkaline batteries provide a steady and reliable power source for an extended period. Here are the best sizes for alkaline batteries for flashlights.


AA batteries are small cylinders of energy and have become an essential part of flashlights.

The key advantage of AA alkaline batteries is their longer lifespan compared to other types. With advancements in technology, manufacturers have increased the capacity and efficiency of these batteries, allowing them to last even longer before needing to be replaced.

It is especially important for flashlights used in emergencies or outdoor activities where access to new batteries may be limited.


When choosing the perfect batteries for your flashlight, Alkaline AAA batteries take the spotlight. Known for their long-lasting power and consistent performance, these compact powerhouses are a staple in every household. But there’s more to AAA batteries than just a reliable energy supply.

The standout feature of Alkaline AAA batteries is their impressive shelf life. Unlike other batteries that tend to lose their charge over time, Alkaline AAA batteries can stay fresh and ready for up to 10 years.

With Alkaline AAAs, you don’t have to worry about constantly recharging or replacing your rechargeable battery packs .

Lithium Battery Sizes for Flashlights

Lithium batteries maintain a consistent level of voltage throughout their discharge cycle, ensuring optimal brightness until the very end. Here are the lithium battery sizes for flashlights.

26650 – Lithium Ion

The 26650 lithium-ion battery is a powerhouse when it comes to flashlight performance. With its larger size and capacity, this battery is designed for heavy-duty use and provides longer runtimes than smaller alternatives.

One of the most notable advantages of the 26650 lithium-ion battery is its high energy density. It can store more power in a smaller space, allowing flashlights powered by these batteries to be compact and lightweight without sacrificing performance.

21700 – Lithium Ion

The 21700 lithium-ion battery has quickly become a popular choice among flashlight enthusiasts, and for good reason. With its larger size and higher capacity, it offers exceptional performance that can be relied upon in any situation.

One of the standout features of the 21700 lithium-ion battery is its extended runtime. With a larger capacity compared to traditional batteries, it allows you to go longer without recharging or replacing it.

14500 – Lithium Ion

Thanks to their high energy density and longer lifespan, lithium-ion batteries have become the go-to choice for many electronic devices. The 14500 lithium-ion battery, specifically designed for flashlights, is no exception.

With a voltage of 3.7V and an average capacity ranging from 600mAh to 1200mAh, this small yet powerful battery provides a reliable light source when needed most.

One of the standout features of the 14500 lithium-ion battery is its rechargeability. Unlike disposable alkaline batteries, which need to be replaced constantly, the lithium-ion battery can be recharged hundreds of times before losing capacity.

16340 – Lithium Ion

The 16340 Lithium Ion battery is popular for flashlight enthusiasts due to its compact size and impressive power output.

With a nominal voltage of 3.7 volts, these batteries deliver enough energy to produce intense beams of light, making them perfect for outdoor activities or emergencies where visibility is crucial.

One unique advantage of the 16340 Lithium Ion battery is its excellent performance in extreme temperatures. Unlike other batteries that lose capacity or become less efficient when exposed to cold or hot conditions, this battery maintains its functionality even in harsh environments.

18650 – Lithium Ion

The 18650 lithium-ion battery has been providing reliable power to flashlight enthusiasts for years, and its popularity shows no signs of dimming. But what sets it apart from other battery options?

One key advantage is its high energy density, which means it can store more power in a smaller size than other rechargeable batteries. It makes the 18650 perfect for flashlights that require long-lasting illumination in a compact design.

Another standout feature of the 18650 is its impressive lifespan. With proper care and maintenance, these batteries can last hundreds of charge cycles before needing replacement.

18350 – Lithium Ion

The 18350 lithium-ion battery has become a popular choice among flashlight enthusiasts, and for good reason. Its compact size allows easy portability, making it the ideal power source for on-the-go adventures.

But what truly sets this battery apart is its impressive performance. With a high energy density and excellent discharge characteristics, the 18350 lithium-ion battery provides flashlights with a long-lasting and reliable power supply.

10180 – Lithium Ion

A lithium-ion battery is an essential component of any high-quality flashlight. Its compact size and lightweight design provide the perfect power source for a portable lighting solution.

The 10180 lithium-ion battery takes this efficiency to a whole new level. Despite its tiny size, it packs quite a punch in terms of energy storage and output capability.

The key advantage of the 10180 lithium-ion battery is its impressive energy density. It can hold a significant amount of charge for its small physical size.

NiMH Batteries

NiMH batteries have become popular for flashlights due to their impressive power output and long-lasting performance. Unlike traditional alkaline batteries, NiMH batteries can deliver a steady stream of consistent power, making them ideal for high-drain devices like flashlights.

Their ability to maintain a stable voltage throughout their discharge cycle ensures that your flashlight won’t dim or lose intensity when you need it most.

They come in various sizes: AA, AAA, C, D, and 9V. 

Which Battery Size is Best for Flashlights?

One popular battery size that balances power and portability is the 18650 lithium-ion battery. These rechargeable batteries are commonly used in high-end flashlights due to their high energy density and impressive performance.

With their compact size yet substantial power output, 18650 batteries can provide long-lasting illumination for extended periods without adding excessive weight or bulkiness.

Another option worth considering is the CR123A lithium battery. Although these non-rechargeable cells have a shorter lifespan than 18650 batteries, they are readily available in most stores and can instantly deliver intense light output.

Final Thoughts

In conclusion, choosing the right battery size for your flashlight depends on your needs and preferences. If you prioritize longer run times and don’t mind the added weight, larger batteries like the D or C size may suit you.

However, if portability is essential and you prefer a lighter flashlight, AA or AAA batteries might be better. Consider your usage patterns and desired brightness levels when making this decision. Remember also to check the manufacturer’s recommendations for optimal battery sizes.

Finding the best battery size will ensure your flashlight performs at its best when you need it most. So, take some time to evaluate your requirements and make an informed decision.