There are a lot of factors that affect how long AA batteries last in an LED flashlight. All these are revealed in this article along with simple explanations.
The most common question people ask about flashlights and batteries is “How long do a AA batteries last in an LED flashlight?” Although this is roughly specified in the packaging of the flashlight, there are still a lot of factors to consider. To clear your mind, this article gives you the leading factors that may affect the longevity of the batteries inside the LED flashlight.
What is AA LED Flashlight?
LED stands for light-emitting diode. They are powerful white light slowly replacing the conventional incandescent bulb. They are significantly more efficient than the incandescent bulb. The white LEDs can produce light on the order of 100 Lumens for every Watt, unlike the incandescent which only gives you 8-10 Lumens for every Watt.
Aside from that, LED flashlights tend to have longer battery life compared to the incandescent on almost the same output. Because of this, some LEDs are permanently installed. But how does LED AA flashlight really work?
As the name suggests — light-emitting diode — it all begins with the diode. These diodes are devices that conduct current in one direction. When an electrical current is applied, electrons travel to two semiconductors. When these electrons fall into the semiconductor, photons are released, therefore, you can see the light.
Yet, to produce light, you need powerful batteries that may last for long. Among the primary sources of power for modern LED flashlight are alkaline batteries, rechargeable batteries, and hand-crank power. This article will focus on the AA batteries which are available almost anywhere.
What are AA Batteries?
Also called double-A, penlite or Mignon, the AA batteries are standard-size cylindrical dry batteries. They are very common for portable electronic devices. You can get a disposable or rechargeable AA battery in the market. Standard-size, meaning, it has a 49.2–50.5 mm in length (including the button terminal) and 13.5–14.5 mm in diameter.
In 2011, AA batteries accounted for 60% of the total battery sales in the US, 58% in Japan and 55% in Switzerland. These numbers are just for the alkaline battery sales.
Factors that May Affect the Longevity of AA Batteries
Even though Lithium batteries are known to last longer, it’s still not a guarantee because other factors may affect the life of the battery. For you to understand them, each major factor is discussed below.
Type of Battery
The most common type of AA batteries present in the market today is the rechargeable batteries, particularly, the NiMH. If you don’t want to invest a little more on rechargeable batteries, you can still opt to have Lithium AA batteries or Alkaline AA batteries. Rechargeable batteries are cost-effective in the long run.
For lithium batteries, you have to distinguish it from Li-ion batteries. The latter is the rechargeable version you can find in mobile devices, laptops, vaping devices and so on. The former, on the other hand, is not intended to be rechargeable. Lithium batteries have a shelf life of around nine years, and they are long-lasting compared to other batteries.
The standard-type AA batteries are the alkaline batteries. This is a non-rechargeable battery and immediately available anywhere. Unfortunately, alkaline AA batteries have some degree of leakage over time as they are slow to self-discharge. There are also chargeable alkaline batteries that have a longer shelf life compared to other rechargeable battery types. However, they can’t handle frequent drain cycles, so they are not ideal for your EDC flashlights.
Here’s a YouTube video comparison of five different Alkaline batteries (from different brands) used on the same flashlight. Although this is just a very simple comparison, you get the idea and maybe perform the same test.
Types of LED Flashlights
Some cheaper LED flashlights use AA batteries with 2-3 1.5V batteries and a resistor (in series with the LED). Though this limits the current through the LED, it may cost some useful life of the battery because the excess current is converted into heat.
There are also better LED flashlights with some electronic circuit that gives better current regulation. They are more efficient and give longer battery life, unlike the resistor. Additionally, you can get more options like variable light output and SOS flashing.
If you have a flashlight with multiple power settings — high, medium, low, ultra-low — the run time of these flashlights depend on different settings. Some manufacturers specify the run time for each setting, others just highlight the run time for the highest setting. If you want your battery to last longer, don’t put your flashlight to high mode all the time. Otherwise, your battery will just have a few hours.
Storage and Temperature
If the batteries have been stored for quite a while in the store before you buy them, chances are, you won’t get the efficiency like the new batteries, unless if you’re getting a lithium battery that has a longer shelf life. But, even if it’s lithium, the longer the battery is stored, the less efficient it will be, especially if it’s exposed to extreme temperatures. But in general, lithium batteries can handle rigorous temperature changes compared to alkaline.
How long do AA batteries last in an LED flashlight depends on a lot of factors. Although with the specifications you can calculate the number of hours the battery can last, it’s just a very rough estimate. The real deal is on how you use it and the type of LED flashlight you have.
In general, you might want to get a lithium battery since it’s known to have low self-discharge and can handle extreme temperatures. For rechargeable batteries, alkaline batteries last longer, but it should be used in your EDC or you won’t get a lasting battery. Therefore, it’s better to get a deeper understanding on these batteries. Otherwise, you won’t get a long-lasting battery that’s suitable for your needs.