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  • What Batteries are Best for Flashlights?

    November 25, 2021 9 min read

    What Batteries are Best for Flashlights?

    Have you ever considered the batteries in your flashlight could prolong your use of the light? If you’re an outdoor enthusiast, you probably have a flashlight on hand and hopefully a decent one at that. If not, feel free to check out our range of flashlights here. In the meantime, did you know that the batteries you use in a flashlight can modify how long the flashlight lasts and how bright they can shine?

    Lithium batteries can be used in some quality flashlight as an alternative to standard batteries. Lithium-Ion or Lithium batteries last considerably longer than other batteries. Not only is their shelf-life and run time longer, but they also produce more energy for brighter lights. 

    With so many different types of batteries available it’s hard to choose the right ones for your flashlight. When it comes to using batteries, there are certain types that will be better used for different objects. It’s confusing and the research is time-consuming, so we’ve done it for you. Read on to power up your knowledge of the best batteries to use in a flashlight. 

    Are Lithium Batteries Good for Flashlights?

    Lithium Ion 18650 flashlight batteries by STKR Concepts

    Lithium batteries, if used correctly, are good for flashlights. They have the advantage of high-energy-density which gives them benefits over other standard batteries. Not only is their ability to last longer in flashlights a great advantage for those of you who need longer run time at night, but there are multiple other benefits to using lithium batteries in a flashlight. 

    Here is a list of the advantages of using lithium batteries in flashlights:

    Longer run time

    Lithium batteries are designed to last longer than other standard batteries (alkaline) and that’s exactly what they do if cared for appropriately. If manufacturers give a warranty date, 2-3 years, for example, you should expect that your lithium batteries will last around that or beyond that timeframe as long as they are used, charged and discharged properly. 

    Low self-discharge

    Higher self-discharging batteries have a lower shelf-life expectancy. The self-discharge of a battery is a chemical reaction that will be affected differently depending on how your battery is stored as well as the state of charge when stored.

    Lithium batteries, if stored and maintained correctly, have a longer shelf-life expectancy because they are a low self-discharging battery. 

    Supply higher voltage

    Lithium batteries hold more energy and can discharge their energy faster than other types of batteries. Although they have an average advertised voltage of 3.6V or 3.7V, when fully charged, they can supply up to 4.2V. 

    Because of the slightly higher voltage supplied in lithium batteries and the lower internal resistance, lithium batteries allow more voltage to reach the bulb in a flashlight which produces a brighter light. 

    Once the voltage sags and reaches the required voltage point of the flashlight, the light emitted will be the same as any other battery used. 


    Lithium batteries are more expensive than other types of batteries. But they are rechargeable. The number of times you can recharge your lithium batteries will depend on how you keep them stored, how you use them in the device, and if you charge them correctly. 

    You might end up saving yourself money on having to purchase new batteries every time their charge runs out by getting up to 1000 or more charge cycles per battery. 

    Shapes and sizes

    Another huge advantage of lithium batteries is that they come in numerous shapes and sizes for convenience. Depending on the type of flashlight you have will depend on which size battery you require. 

    Lithium batteries aren’t typically advertised in sizes like AA, AAA, C, D, etc. but are measured by number. 

    Here’s a list of lithium battery sizes by number and a short description:

    14500 – Similar in size to a regular AA battery

    16340 – Close to the size of a CR123A battery

    18650 – Also similar to a AA battery size but with a larger girth and length, the 18650 is most popular for flashlight use

    26650 – Much larger high-power battery, devices are made specifically for these batteries

    Battery protection

    Some manufacturers supply lithium battery protection like overload, overheat, and over-discharge safety guards for their flashlight (among other) devices. These protections also assist in prolonging the life of the lithium battery.  

    Battery protection circuits will prevent over-discharging, over-heating, and discharging too quickly. 

    Can withstand extremely low temperatures

    Temperature can significantly impact the way lithium batteries work and are charged. Lithium batteries have been called cold-weather performance batteries and can work efficiently between minus 4°F (-20°C) and 140°F (60°C). 


    What Batteries are Used in Flashlights?

    The most common types of batteries used in flashlights are lithium and alkaline.

    There are different types of flashlights for all different types of activities. Flashlights range in sizes, colors, shapes, lengths, uses, and voltage requirements. From outdoor activities like hunting and camping to emergency situations like power outages and medical emergencies, flashlights are used for different purposes around the world. 

    This means that not all flashlights will accept just any type of battery. 

    Batteries can be defined as rechargeable and non-rechargeable:


    Rechargeable batteries could save you some dollars if you store and charge them correctly. AA and AAA are the most common sizes used for flashlight batteries and you can purchase either alkaline or lithium which we’ll cover a little further below. 


    Non-rechargeable batteries are a “use and dispose of” design. Meaning once they’ve run out of charge, they’re empty, useless, and cannot be used again. 

    Non-rechargeable batteries are typically cheaper than chargeable batteries, don’t last as long, and are convenient for small-powered devices. 

    Some manufacturers will advise they’re fine to throw away in your household trash while others even request you send them back to the manufacturer for recycling. 

    1.5 Volt

    The most common, used, and known batteries are known as AA, AAA, C, and D batteries. 1.5v batteries are the most widely used on the planet. 

    The batteries that use 1.5-volt are typically used for devices like remote controls, clocks, children’s toys, cameras, flashlights, and much more. 

    Primary non-rechargeable batteries are generally known as non-rechargeable alkaline 1.5-volt batteries. 

    3 Volt

    Also described as ‘coin’ batteries, CR123A which are ideal for LED flashlights and extremely low temperatures, are also commonly used in household electronics, security systems, watches, and medical devices. 

    You can also purchase 3v batteries in the typical cylinder shape like AA and AAA batteries.  


    Lithium batteries can come in similar shapes and sizes to AA, AAA, C, D, etc. and are longer lasting because they have a voltage of up to 3.7 (4.2 unadvertised). They are commonly used for high-performance flashlights, garage and workshop flashlight lighting, and lithium batteries are also commonly found in laptops. 

    You can check out this table of battery sizes, types, and volts here for further information. 

    What is the Difference Between a Lithium Battery and an Alkaline Battery?

    Lithium and alkaline batteries are made from different materials so they both have their advantages and their drawbacks. 


    Alkaline is made from steel, zinc, manganese, potassium, and graphite. 

    Alkaline is not extremely useful for powering high-output flashlights. They are great and have been great since the 1950s, for everyday electronic devices that don’t require high-energy output and they are usually much cheaper than the newer lithium style batteries. 

    The alkaline battery accounts for 80% of all the batteries manufactured in the United States. – onlinecomponents.com


    Lithium batteries are made from lithium and carbon. Lithium is a highly reactive element, and this is what gives lithium batteries their high energy density

    Lithium batteries are lighter than alkaline so they work well in lightweight design flashlights to not add any extra weight and they’re ideal in outdoor situations where a flashlight might be subject to colder temperatures, (camping, hiking, hunting). 

    Lithium batteries are also a good option for those who don’t use their flashlight very often because the shelf-life is longer. 

    Here is a table of the pros and cons of both alkaline and lithium batteries so that you can see the common differences between the two:





    Low voltage


    Not useful for high-powered flashlights


    Bulkier and heavier

    Common sizes 

    Risk of exploding with faulty charging

    Used for entry-level flashlights

    Can leak corrosive chemicals that ruin the device they’re used in. 

    Used for some mid-level flashlights

    Alkaline chemicals are toxic

    Good for everyday use

    Can’t be recharged as often as lithium

    Easy disposal

    Can’t function in extreme climates

    Rechargeable variety

    Decrease voltage output throughout its lifespan


    Longer-lasting life (hold its charge)

    More expensive than disposable

    Longer lasting shelf-life

    Restrictions are in place by some airline companies. 

    Can withstand wide temperature range

    Contains flammable electrolyte 

    High-energy density and output

    Uncommon sizes

    Low self-discharge

    Over-charging causes damage

    Rechargeable variety

    Can be ruined if the charge runs below 2.5v

    Can be recharged up to 1000 and more times depending on maintenance and care

    Extreme heat can cause damage and batteries to degrade quicker

    Holds voltage output through its lifespan

    Can burst into flame

    As you can see from the above table, lithium batteries are better suited to high-performance flashlights. You can see our range of rechargeable 18650 flashlight batteries at STKR Concepts here. 

    What are the Disadvantages of Lithium-ion Batteries?

    As you can see, lithium batteries are great in some respects but can be lacking in others. Let’s go into a little more detail about some of the disadvantages of lithium batteries. 

    Over-charging causes damage

    The right charger for your battery can be crucial to making sure you don’t overcharge them and risk damaging them before their use-by time is up. Over-charging is what happens when a battery is charged above its specified maximum voltage. This creates pressure and heat inside the battery. 

    This can damage the battery and possibly the device you use the lithium battery for. 

    Should not be discharged below 2.5 volts

    If you want to render your lithium-ion batteries useless because you have the cash to spare, discharge them too quickly and discharge them below 2.5 volts. That’ll do the trick. 

    But, if like us at STKR Concepts, you want to maintain your battery life, don’t let your battery be discharged below 2.5v for best results. 

    The protection circuit in the battery stops providing power to the battery if the charge drops too low. It’s for this reason that lithium battery-powered flashlights might have Low-Voltage Protection (LVP) installed in the flashlight device. 

    Putting the battery in the wrong way can damage your device

    Yes, it’s true. If you put the wrong end of a lithium battery into the wrong end of your flashlight, you could permanently ruin your flashlight. Putting the battery in backward can cause permanent damage and sometimes even a fire. 

    How Long Does a AA Battery Last in a Flashlight?

    There are a few factors to consider when asking the question of how long a AA battery will last in a flashlight. 

    • The battery type (Alkaline or lithium for example).
    • How often the flashlight is used. 
    • The type of flashlight in question (regular or high-performing).
    • The brand of the battery. 
    • The brand of the flashlight. 
    • The flashlight settings (SOS, strobe, white-light, floodlight, beam etc.)

    You may know that flashlights can have multiple settings, SOS modes, strobe, floodlight, beam, full, medium, or low brightness, optimal colors for hunting or medical purposes, and many more. Depending on how often you use your flashlight as well as the main setting you’re using will alter how long a AA battery lasts in the device. 

    We recommend steering clear of no-name brands to avoid any disappointment. 

    Typically, a standard AA LED Flashlight will last up to 7 hours. The higher the lumens, the less time your flashlight batteries will last. The lower the output of lumens, the more time your batteries will last. 

    For example

    A  B.A.M.F.F. 4.0XL flashlight with an output of 450 lumens on high and 40 lumens on low could last up to 20 hours. 

    A flashlight used in strobe mode might only last between 2 and 8 hours. 

    Here are a few things you can do to ensure the longevity of your flashlight:

    • Store them correctly when not being used.
    • Take them out of the device, they usually last longer. 
    • Keep away from harsh temperatures - minus 4°F (-20°C) and 140°F (60°C).
    • Store in the dark so there’s less risk of sun exposure damage. 
    • Store away from other metals. 

    Just quickly, in short, lumens are what provide the brightness of your light. 

    You can read more about lumens here to see how we at STKR Concepts view lumens. 


    Lithium batteries last much longer than other types of batteries, can endure harsher temperatures, and are much more light efficient in higher-powered flashlights. Because of these reasons, lithium batteries are better used for tactical, lightweight flashlights for outdoor enthusiasts and for those in professions where you might require brighter lights for longer periods of time. 

    At stkrconcepts.com we have a range of flashlights and batteries for sale. Check out our battery range here for more information. It’s always best to read your flashlight manual and instructions before choosing the right batteries for your device.

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