Battery Sizes for Flashlights: A Guide for Beginners


Are you new to the flashlight world? All the battery sizes for flashlights running around make it easy to feel overwhelmed. But first, you must wrap your head around concepts like mAh and the different lithium-ion batteries available on the market.

If you’re unfamiliar with this topic, you’re in luck. This article will provide all the juicy details about flashlight battery sizes and more. 

Are you ready? Let’s go!

What kind of Batteries works for Flashlights?

Man putting a battery in a flashlight

Man putting a battery in a flashlight.

Flashlights can accommodate a wide variety of batteries ranging from Ni-MH to alkaline. Further, some LED flashlights often feature in-built batteries with rechargeable characteristics.

However, lithium-ion batteries are incredibly effective for powering ultra-bright flashlights. In other words, their high energy output makes them the go-to for these flashlights.

In addition, these batteries are cost-effective due to their rechargeable features and power output for LED flashlights.

Therefore, lithium-ion batteries provide more power and longer run times.

What does mAh mean in Flashlight Batteries?

Multiple batteries

Multiple batteries

mAh translates to milliamps per hour and a widespread electrical charge unit. So, that’s why most lithium-ion battery manufacturers advertise their product’s mAh.

Usually, if you have a higher mAh, the battery may have a longer run time.

For instance, let’s compare a 3100 and 2600 mAh battery. With the 3100 mAh model, you’ll enjoy up to 30% more run time than 2600 mAh.

However, mAh is not the only unit determining a battery’s effectiveness. Also, it would be best if you considered voltage.

Lithium-Ion batteries with lower voltage and higher milliamps won’t provide as much power as variants with higher voltage and lower milliamps.

What are the Different Lithium-Ion Battery Sizes?

Lithium-ion batteries

Lithium-ion batteries

As mentioned earlier, batteries come in various sizes, and lithium-ion models are no exception. And some LED flashlights can accommodate different kinds of lithium-ion batteries. So, let’s look at these different types.

26650 Li-Ion Battery

This battery size is the biggest on this list. Further, 26650 lithium-ion batteries are compatible with flashlights, known as a soda can lights.

However, these flashlights are not ideal for everyday use due to their large sizes.

But they dish out incredible outputs. In addition, some 26650 batteries feature a high 5000 mAh capacity, and others may even provide higher.

21700 Li-Ion Battery

Unlike the 26650 models, 21700 Li-Ion batteries feature more compact sizes. Also, they don’t sacrifice power to achieve smaller forms.

Additionally, flashlights ranging from heavy-duty to everyday carry lights can use 21700 batteries. And 5000 mAh is the maximum capacity for 21700 Li-Ion batteries.

18650 Li-Ion Battery

Currently, 18650 Li-Ion batteries are the most widespread for LED flashlights. Although their maximum capacities are 3500 mAh, these smaller batteries are ideal for hand-held, everyday carry, and tactical flashlights.

In addition, some advanced 18650 Li-Ion batteries have built-in micro USB charging ports. This innovation is perfect for flashlights without rechargeable features.

So, you won’t have to deal with battery chargers, and your flashlight will enjoy longer run times.

14500 Li-Ion Battery

These battery sizes are incredibly similar to AA models. Interestingly, 14500 Li-Ion batteries can fit everyday carry and pocket flashlights. However, the highest mAh you may find for these sizes is 800.

16340 Li-Ion Battery

Lastly, the 16340 Li-Ion battery is shorter but wider than the 14500 Li-ion battery. These battery sizes are similar to CR123 lithium batteries and can easily power pockets and everyday carry flashlights.

Moreover, 700 mAh is the highest capacity from these batteries.

What Kind of Battery Should you Get for Your LED Flashlight?

Hands holding blue batteries

The answer to this question depends on the type of flashlight. For example, some flashlights can handle 21700 batteries, while others may accommodate 18650 or 16340 batteries.

In addition, you should look out for flashlights requiring flat or button-top batteries. Also, remember that some high-end tactical flashlights may be picky about the batteries you can use.

We recommend purchasing batteries from reputable brands because they have higher chances of working in all flashlight ranges. You may get different results from cheaper online battery stores.

Rounding Up

Flashlights can utilize various battery sizes and types, but lithium-ion variants are more advantageous. In addition, Li-Ion batteries are economical and cost-effective due to their rechargeable features.

Further, some lithium-ion batteries even incorporate USB-C or micro USB ports to bring rechargeable features to non-rechargeable flashlights. Also, you can anticipate longer run times and higher outputs from Li-Ion batteries.

However, Lithium-batteries don’t have the best shelf life. Hence, they drain over time and require charging to avoid entering a deep discharge state.

Do you have more questions? Feel free to contact us, and we’ll be glad to help.

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