How Long Do Flashlight Batteries Last?

 Last Updated on May, 2024

Batteries for flashlights have varying degrees of performance. While some batteries will only last for a few minutes, others last for hours and even days and months. 

The battery life on your flashlight depends very much on the mode that you use it in. Batteries for flashlights are intended to work on varying levels of performance based on the output lumens of the mode opted for. 

While low modes allow for batteries to perform for even days and months, on high and turbo modes, the battery life is much shorter. 

Quick Summary

The battery life of a flashlight depends on the type of battery and the performance mode chosen.

Lithium-ion batteries are the best-performing type of flashlight battery, and they can have a shelf life of up to 10 years and a runtime of up to 650 hours.

To maximize the battery life of your flashlight, use the lowest mode and clean the battery from time to time if possible.

What is the Average Battery Life of Flashlights?

a human holding a flashlight

LED flashlights, on average, work 1.5 to 7 hours on high and turbo mode and up to 50 hours on a low setting. 

As mentioned, the flashlight’s battery life depends on the mode that you choose. Modes with lower lumens output will drain the battery slower. (Many flashlights have multiple settings or modes.) 

This is why some batteries work for days and months in ultra-low or eco mode. On average, however, a heavy-duty battery will work on high or turbo modes for about 12 to 15 hours. 

The performance of the flashlight is very much dependent on the TYPE of battery used. While some batteries provide better performance and runtime (such as a heavy-duty battery), others produce less than average results – due to the quality of performance of the battery. 

What Kind of Batteries Do Flashlights Use?

There are two main kinds of batteries used in flashlights; lithium batteries and alkaline batteries. Lithium batteries are designed to last much longer than alkaline. Hence, if you are looking for a flashlight with better performance, ideally, it should be running on a lithium battery. 

There are a host of lithium-ion batteries, including the 18650 and the 21700 lithium-ion batteries, which are used in ELECTRIC CARS! (Imagine having that much power and reliability on a flashlight! The work withstanding extreme temperatures!)

As mentioned, how long batteries will last on a flashlight will depend on two main things; the type of battery and the performance mode opted.

With lithium-ion batteries being the better option in terms of performance, batteries such as the AAA LED flashlight batteries and the Double A (AA) batteries are alkaline.

The flashlight’s battery life is something that is important for many people. In fact, LED flashlight battery life is often the deciding factor in the purchase decision of the flashlight for many people. 

Related article: Battery Sizes for Flashlights

How Long will AA and AAA Batteries Last in a LED Flashlight?

flashlight with battery

AAA batteries will work on a LED flashlight for about 30 minutes when using a 3W LED light. In comparison, an AA battery, on average, works for about 1 to 7 hours when in high mode.

AAA batteries can also produce this much runtime if the lumens output of the LED light is lower (smaller light.) 

AA and AAA batteries are both Alkaline, which are not the best-performing types of LED flashlight batteries. When you compare AA and AAA batteries to the batteries that are used in ELECTRIC CARS, you are comparing copper to gold. 

The battery life of both AA and AAA batteries are not very impressive when it comes to LED flashlights.

You want your LED flashlight to work for days and months, which feels like a far-fetched dream when you consider an LED flashlight that runs alkaline batteries such as AAA and AA.

Best LED Flashlight Batteries – Flashlight Battery Life

Zinc Chloride batteries have a great shelf life of 2 to 4 YEARS! Even more impressively, lithium-ion batteries are claimed to have a shelf life of up to TEN YEARS!

However, the shelf life isn’t the same as runtime on a flashlight. For instance, Zinc Chloride flashlights have a runtime of about 55 hours (hours of illumination.) You might think this is good runtime, but wait till you hear the runtimes of lithium-ion batteries. 

The 18650 lithium-ion battery has a battery life (runtime) of 650 HOURS! That is more than 10 times better performance than a Zinc Chloride battery. LED flashlights that use lithium-ion batteries, such as the 18650, are considered better-performance LED flashlights. 

Hence, when picking a LED flashlight, you should always check to see what battery the LED flashlight uses. LED flashlights use an array of batteries, and not every battery offers the same level of performance. 

The 21700 lithium-ion battery is not as impressive as the 18650. The batteries (21700) have a runtime (battery life) of about 150 hours! Though impressive, not as impressive as the 18650. 

The Olight Baton 3 Pro light runs on a 18650 lithium-ion battery. On the lowest mode, this flashlight has a battery life of 120 DAYS! – That is 4 months of lighting on a single charge of the battery. 

When it comes to picking an LED Flashlight, you HAVE TO check the battery type.

Worst Flashlight Batteries – Flashlight Battery Life

Alkalines (alkaline batteries) operate in a different manner to heavy-duty lithium batteries. There are various factors that come into play. By factors, we mean battery chemistry. When one alkaline is replaced with another, it produces varying degrees of performance. 

Hence not to badmouth all alkaline batteries, but high-performance flashlights with more maximum lumens (LED lights) are unlikely to run on alkaline batteries. The higher lumens mean a greater drain on the battery, requiring a heavy-duty battery to power the flashlight. 

Batteries are energy, and AAA and AA batteries do not deliver as much energy as lithium batteries. What makes a battery weak is the energy output. Zinc Carbon batteries, for instance, cannot replace the power and performance of the 18650.

Zinc Carbon is too a weak battery that offers only minutes, if not a few hours, of runtime. (When compared to 120 DAYS, this is nothing.) 

Hence, in order to determine the worst batteries, you need to understand the difference between alkaline and lithium batteries. 

I have seen reviews of people who have stated that their flashlight, which runs on triple A batteries, only had a runtime of 5 minutes!

Depending on the devices the battery operates on, performance will vary. Though triple A works perfectly fine for a remote control, it isn’t the BEST battery for a flashlight. 

While NiMH batteries are good (NiMH batteries are not the worst), there are better options of lithium batteries in the market. 

Related article: Can you recycle flashlight batteries?

Flashlight with Best Battery Life: Which Battery Has Best Battery Life?

a flashlight on the table

We wanted to test a few flashlights, so we got our hands on some flashlights with the BEST battery life. 

Though flashlights with better batteries can cost more, it is often worth the purchase (great value for money.)

Now that you have a better understanding as to why some batteries last longer than others, the brightness of the flashlight will be one of the main factors in deciding performance.

The dimmer the light, the higher run time. When the brightness is set to low modes (eco mode usually being the level of lowest brightness), the battery of these flashlights often works for DAYS!

The Olight Baton 3 Pro (your new flashlight?) will work on a low setting for 120 DAYS!

Hence the crown after a power draw for the BEST flashlight with battery life goes to the Olight Baton 3 Pro (Higher Energy Capacity Flashlight.) – You won’t need extra batteries; it uses a rechargeable 18650 lithium battery.

You won’t need new batteries, and you won’t need more batteries, either. The chances of a power outage with the 18650 battery are lower.

Tips to Protect the Batteries of Flashlights

Tip 1

If your flashlight has mode memory, it will remember the mode that was previously used prior to turning the flashlight off. Ensure to keep your flashlight on low setting or eco mode whenever possible to conserve battery life. 

Tip 2 

Clean your batteries for corrosion. If you have access to the battery on your flashlight, you may want to clean it from time to time. The build-up of corrosion is what kills batteries. Hence, clean them when and if possible. 

Tip 3

If you don’t plan to use the flashlight for a long time, it is recommended that you remove the batteries from the flashlight and store them elsewhere until you have to use the flashlight again. 

Simply leaving the batteries in an unused flashlight will cause the batteries to drain and could potentially break the flashlight. 


Batteries for flashlights have varying degrees of performance. Depending on the flashlight you choose, the battery used will vary. Hence it is very important that you check the type of battery used and the runtimes of specific modes to ensure that you are getting a good-quality flashlight. 

At the end of the day, do you really need a flashlight that will only work for 30 minutes before you have to go about changing batteries? This can be a real hassle, not to mention havoc on the planet. 

With so many advanced flashlights in the market, you have the choice to go rechargeable. If you need directions on picking a flashlight, we recommend you read this article on the BEST long-lasting flashlights available on the market!


It is recommended to replace the batteries in a flashlight every few months, particularly if it has not been used for some time.

Yes, lithium batteries are more long-lasting than alkaline ones due to their superior performance.

On average, flashlight batteries can last anywhere from 1 to 7 hours.

You should replace the batteries on your flashlight when the light dims, the battery indicator shows a low level, or after a few months of inactivity.

The 18650 lithium battery is widely regarded as the best battery for a flashlight due to its use in electric cars.

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Dillon Morrison
I have been involved in the flashlight community since 2007. My brother has a flashlight shop from where I have tested and reviewed more than 600+ different types of flashlights. You can find more about me here.

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