Flashlight Power Source: What to Know & Types of Batteries

By Derrick Ferrell
Updated on
Flashlight charging via power bank
Image credit: Nor Gal

For light to be produced, there must be a power source. In the case of EDC flashlights, which are designed to be portable, the power source comes in the form of batteries. And since there are many different battery options on the market, EDC flashlight users need to consider this aspect in order to get the most out of their product.

Disposable vs. Rechargeable Batteries

Disposable batteries are the common batteries that you see in remotes, toys, and other everyday electronic gadgets. Once they lose charge, they need to be properly disposed of (recycled).

On the other hand, rechargeable batteries can be recharged when connected to an electric charge (using a proper adapter), which causes a reverse chemical reaction.

Disposable batteries mainly come in standard sizes while rechargeable ones come in varying sizes, shapes, and dimensions to best fit the designated product.

Some flashlights come equipped with rechargeable batteries while some do not pack batteries at all. In the case of the latter, users can decide if they want to use disposable or rechargeable batteries if the battery slot is of a universal size.

Rechargeable batteries are more expensive, yet in the long run, they are more cost-efficient and a more economic choice.

Furthermore, rechargeable accumulators also pose a lower negative impact on the environment compared to disposable ones. Sadly, an enormous amount of single-use batteries still end up in the landfill. And since batteries contain a lot of toxic chemicals, it should be every user’s concern to do the best to minimize that negative impact.

With all that in mind, rechargeable batteries are a clear overall winner.

In-Flashlight-Rechargeable vs. Adapter Rechargeable

As mentioned, there are many types of rechargeable batteries and also many types of flashlights. In some cases, users need to take the batteries out of the EDC flashlight and use an adapter to charge them. In other instances, the battery can be charged while inside the flashlight by plugging the flashlight into the socket using its adapter.

From the users’ point of view, flashlights that offer both options definitely come on top. Though, in reality, the majority of flashlights operating based on rechargeable batteries offer either one or the other charging method.

Being able to charge the batteries outside of the flashlight can be extremely practical especially if users obtain multiple batteries that can be used interchangeably. On the other hand, taking the batteries out of the flashlight compared to simply plugging a cable into the flashlight directly can be time-consuming and less practical. With that in mind, users will need to go with the option best suited for them.

These days, USB chargeable flashlights are very popular. Using a micro or mini USB, one can simply charge them using the socket adapters, laptops, computers, car chargers, or battery banks, which is extremely practical when on the go.

How Does Battery Life Work?

When it comes to the battery life of a flashlight, it is mainly up to the capacity of the battery and its mAh rating. The quality of the battery plays a role too, but it is mainly the size. The larger the battery or more individual batteries inside the flashlight, the more charge the flashlight can get and the longer it will be able to shine. Of course, the output power of the flashlight also plays a huge role.

When considering disposable batteries, the battery life only refers to the period that will take for the battery to lose its charge. But when talking about rechargeable accumulators, the battery life has a twofold meaning. One, it refers to the capacity of a single charge, and two, it refers to the overall number of charging cycles that a battery is designed to undergo.

The latter varies and highly depends on the quality of the battery. Since there are no perfect rechargeable batteries, users need to be aware that a rechargeable battery will lose its ability to hold a full charge over time. On average, an apparent degradation in capacity is noticed somewhere after 15 – 18 months.

When finding an ideal flashlight, users need to consider their most common use case. Do they need their flashlights occasionally for a couple of minutes or do they need them to light the path on a long night walk? These two examples call for two very different battery capacities.

Once the users have determined their needs, countless options are available- from flashlights that can run for no more than an hour on a single charge (or before replacing the batteries) to those capable of providing up to 520 hours of straight use.

Battery Types

Here we put together a list of the very common as well as the less common battery types that are found in EDC flashlights. 

Alkaline Non-Rechargeable Batteries

When people hear of batteries, the majority think of Alkaline batteries. They are probably still the most commonly used ones. They are relatively inexpensive and come in various sizes. Of course, the larger the size, the more charge the battery can hold.

Alkaline batteries’ common sizes include AAA, AA, C, D, 9-volt, and button cells. Like all devices, a particular flashlight model can host only one particular battery size and a particular number of units.

These types of batteries are widely accessible, which makes things very practical as one can stop at any kiosk and buy them when needed.

Their major downside is that they have a highly negative impact on the environment and a higher tendency to leaks, which can damage a flashlight. If using this type of battery, users should turn on their flashlights at least once a week and never leave the batteries inside if the flashlight is not in use for a longer period.

Compared to other batteries, alkaline non-rechargeable batteries have a rather low power output, which means that the lumens output may not reach its maximum. The capacity is also not impressive, which results in a shorter run time. 

Lithium Non-Rechargeable Batteries

Since there is often confusion with these batteries, users need to know that these are NOT Lithium-Ion batteries. Just like alkaline batteries, they also come in AAA, AA, 9-Volt, and small cylinder (CR123A) sizes.

They have a very low self-discharge rate and are thus suitable for long-term hold (shelf life of up to 10 years). Lithium batteries perform impressively well in low temperatures, even in below-freezing conditions.

Rechargeable NiMN

Nickel-Metal Hydride (NiMN) batteries are very good all-around batteries. They normally come in AAA, AA, C, D, 9-Volt, and 12-Volt sizes. They are rechargeable but do not have a very good shelf life.

Rechargeable Li-Ion

Rechargeable Li-Ion (Lithium Ion) batteries are currently the most popular batteries on the market. They are what most smartphones pack. The best kinds of flashlights with rechargeable batteries will rely on these types of batteries. They have a long shelf life and can store charge very efficiently. On top, they can be charged rather fast.

There are multiple sizes of Li-Ion batteries used in flashlights:

  • 14500: This size is very similar to AA; however, a flashlight operable on AA may not operate in 14500 batteries. Specs must always be checked to ensure that interchangeability can be applied.
  • 16340: This size is rather similar to CR123A/RCR123A batteries but slightly longer and with different voltages. Checking the flashlights’ specs for possibly switching between the two types of batteries is essential.
  • 18650: This is one of the most popular rechargeable batteries for flashlights. It is larger in both length and diameter than AA and thus offers a larger capacity and a lot of power. Note that 18650 batteries may vary in size and style between different manufacturers. Typically they provide 3.6 or 3.7 Volts, while the milliamp (mAh) ratings vary. The higher the mAh, the longer the battery can run on a single charge. Users operating in sub-zero degrees need to know that these batteries do not perform optimally in such cold conditions.
  • 26650: This is a relatively large battery designed to power very powerful flashlights. The 26650 batteries offer high performance and high capacity, which obviously demands a larger diameter and longer length. Typically, the 26650 has a high mAh rating, which gives longer runs between charges.

Different Battery Types & Lumens

The table below denotes the maximum lumen output for a particular type of battery. The numbers may vary slightly as this is just a guideline.

Battery TypeMax Lumen Output
AAA alkaline130
AA Alkaline130
16340 Li-ion rechargeable450 – 550
CR123A Lithium270
14500 Li-ion rechargeable320
NiMH rechargeable150
18650 Li-ion rechargeable960
26650 Li-ion rechargeable1000