Nitecore 21700 Li-Ion Batteries
The 21700 batteries are rechargeable Lithium-Ion batteries which have grown in popularity with electric cars and they're considered to be the future of cylindrical batteries. One 21700 battery measures 21mm in diameter and 70mm in length, compared to an 18650 battery, which you may be more familiar with, that is 18mm in diameter and 65mm long.
A longer mAh capacity means longer runtime. A 21700 battery has an up to 5000mAh capacity, whereas a 18650 battery has an up to 3600mAh.
Nitecore has already released a small collection of 21700 battery flashlights, including the New P12, New P30, HC35, E4K and i4000R. If you’re looking to get a charger for your 21700 battery flashlight, look into the UI1 and UI2, which are budget friendly USB chargers, or for a full digital experience, try the UMS2 and UMS4. These chargers are designed to support the length and width of the 21700 Li-Ion batteries. But also, you could skip the charger all together and use the USB C port located on the battery itself. You can directly connect your USB C charger to your 21700 battery.
These features come included at the New P30 and the E4K. If you haven’t tried them out yet, the shop link is right here:
Other number of batteries you might have seen are 16340 which are the small ones:
and the 14500 batteries, the “normal” looking ones, with 14mm diameter and 50mm in length, 850mAh:
Still, these are not the same with the AA batteries, even though the size is the same, the voltage is different. The 14500 Li-Ion battery has 3.7 Volts (fully charged 4.2V), while regular Ni-Mh AA battery is 1.2 Volts / 1.5 Volts. So 4.2V vs. 1.5V is not the same and therefore the device could get damaged by using incompatible batteries.
The last category we’re going to mention consists of the small AAA batteries which have an even smaller voltage.
When you’re looking to buy a flashlight, based on the batteries used, you will be interested in the battery size, capacity and the discharge rate.
The capacity affects how long your light can run, not how bright. The brightness is controlled by the maximum discharge rate. The brighter the flashlight, the more current it needs to sustain the light.
Let’s take the New P12 for example, to sustain 1200 lumens, it needs a discharge rate of 4A. So it’s compatible with an 18650 battery, but it comes with a 21700 (5000mAh) built in battery. Further more, optional 21700 batteries of 4000mAh and 4500mAh capacity are compatible as well.
The P20i, with 1800 lumens, needs a discharge rate of 8A. That’s why the 4000mAh capacity battery is still a good one for it, but P20i has incorporated the NEW Nitecore battery, which is 21700-i series:
The I4000R with 4400 lumens, has a discharge rate of 15A, so it needs the biggest capacity: 5000mAh Li-ion battery. The I4000R has a built in 21700-i Li-ion battery as well. What makes this type of battery special is the positive and negative polarity at both ends with a high energy density. Basically it enables a high efficient output by minimizing the loss of power due to internal resistance.
Note: If the battery doesn’t show a discharge rate – that means it only has a discharge rate of 4A.
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