Review Nitecore E4K

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roma58's picture
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Review Nitecore E4K

The Nitecore E4K was sent to me directly by Nitecore for the review.

For technical details of the torch:
For the purchase:







The Nitecore E4K is part of the new generation of Nitecore EDC torches they adopt the new lithium battery in 21700 format. The Nitecore E4K, 2020 novelty of the series Explorer, is a very compact pocket EDC just over 11 cm long, made with a aluminum unibody design. Inside, included in the package, we find a battery in 21700 5000 mAh format, rechargeable through the supplied USB-C cable, which allows a long autonomy. The Nitecore E4K offers 4400 lumens of power for one lighting distance of 211 meters. It has 5 light levels and 3 special modes. The Nitecore E4K has an IP68 waterproof rating and is 1 meter impact resistant.







The Nitecore E4K arrives in the classic yellow / black cardboard package. On the four sides the main features that distinguish the torch are listed.
Inside we find:

- Nitecore E4K flashlight
- Nitecore 21700 rechargeable lithium-ion battery (NL2150HPR 5.000 mAh)
- USB-C charging cable
- Clip, lanyard and spare O-ring
- Holster
- CR123 Battery Magazine
- Manual and warranty









• Utilizes 4 x CREE XP-L2 V6 LEDs with a max output of 4,400 lumens
• An optical system combined with crystal coating and “Precision Digital Optics Technology” (PDOT)
• Maximum peak beam intensity of 11,100cd and maximum throw of 211 meters
• Highly efficient constant current circuit provides a stable output for up to 700 hours
• One side switch specially designed for outdoor applications controls 5 brightness levels and 3 special modes
• STROBE Mode uses randomly changing frequencies for stronger dizzying effects
• A power indicator beneath the side switch indicates the remaining battery power (Patent No. ZL201220057767.4)
• The power indicator can display the battery voltage (±0.1V)
• NITECORE 21700 rechargeable Li-ion battery (NL2150HPR 5,000mAh) included
• Incorporated Advanced Temperature Regulation (ATR) module (Patent No. ZL201510534543.6)
• Electronic reverse polarity protection
• Optical lenses with double-sided scratch resistant coating
• Constructed from aero grade aluminum alloy
• HA III military grade hard-anodized finish
• Waterproof in accordance with IP68 (2 meters submersible)
• Impact resistant to 1 meter
• Tail stand capability


Length: 117.56mm (4.63”)
Head Diameter: 28.6mm (1.13”)
Tube Diameter: 25.8mm (1.02”)
Tail Diameter: 28.1mm (1.11”)
Weight: 80g (2.82oz)





In the sales package in addition to the Nitecore E4K we find some accessories including the 21700 lithium battery, the holster and the CR123 / RCR123 battery adapter.

The supplied battery is rechargeable via a USB-C socket on the top of the battery. Just plug in the USB cable included in the package to a 5V socket to start charging. When the battery is charging it turns on, in the part
top (towards the positive), a red LED, while when charging is complete, a green LED lights up.
A peculiarity of the battery that I noticed is the hexagonal positive button.

Some features of the 21700 NL2150HPR battery:


- Capacity 5000 mAh
- Voltage 3.6V
- Output> 15A for high performance
- Integrated pressure relief valve
- Microporous barrier for heat dissipation
- Integrated PTC for overvoltage protection
- Cathode and anode in nickel-plated stainless steel
- Abrasion resistant coating
- Weight 75g
- Length 76mm
- Diameter 21.6mm





The holster that we find inside the Nitecore E4K box is essential but well made. It is made of fairly soft cordura with a closure tore up.

At the rear we find the D-ring at the top and centrally a double loop, one of which is tear-off. Once inserted into the holster, the E4K remains firm.





The Nitecore E4K is well built in aluminum alloy with anodized finish. It has a CNC-worked Unibody design and has compact dimensions measuring just over 11cm in length. The only part that can be unscrewed is the tail.

On the body and on tail we find a rhombus knurling that facilitates the grip while on the head the big circular switch stands out. The writings present on the head and tail they are well made and easy to read.
The Nitecore E4K has an IP68 waterproof rating (submersible at 2 meters) and withstands impact up to 1 meter.




Above the head stands the large electronic switch. This switch in rubbery material, surrounded by a beautiful colored metal ring steel, allows us to completely manage the user interface (UI) consisting of 5 levels and 3 special modes.

Around the button we find, from on both sides, the cooling fins are not so deep. Under the rubber of the side button (power indicator) LEDs show the remaining battery charge.
When the light is off, briefly press the power button and the power indicator will flash to indicate power residual:

1. The flashing three times indicates that the power is greater than 50%;
2. Flashing twice indicates that the power is less than 50%;
3. Flashing once indicates that the power is less than 10%.

Also when we insert the battery and close the tail cap, the power indicator under the switch will flash to show the battery voltage (± 0.1 V).
• For example, when the battery voltage is 4.2 V, the power indicator will flash 4 times followed by a pause of 1.5 seconds and 2 more flashes.






On the head of the Nitecore E4K we find 4 small SMO parables with the 4 CREE XP-L2 V6 LEDs with a cool white tint. The optical system it has crystal coating and precision digital technology (PDOT). The Bezel is smooth while the glass is slightly hollowed out below it.
The maximum power in lumens developed by the 4 LEDs is 4400.




The central body of the Nitecore E4K has a non-slip diamond-shaped knurling while in the lower part we find fins of cooling that facilitate the disposal of the heat produced during the use of the E4K at the highest light levels.

The threads, square in shape, they arrive well lubricated. Being anodized they allow, by slightly unscrewing the tail, the mechanical locking of the torch. There is also the O-ring seal for protection against water and dust.

On the body it is possible to insert the two-way clip, included in the sales package. On the clip it is then possible to insert the lanyard that we find in the box.




At the two poles, for contact with the battery, we find a plated spring, of moderate thickness, on the negative and a button plated on the positive.
The Nitecore E4K has electronic protection against reverse polarity. The only unscrewable part of the Nitecore E4K is the tail cap. On the tail cap the rhombic knurling is similar to that seen on the torch body.

There are no holes for inserting the lanyard. The tail design is classic cap, flat base, which allows the E4K to be placed upright (candle).




The Nitecore E4K near other torches with 21700 battery:




The Nitecore E4K offers 2 user modes, daily mode and tactical mode for different users and situations.
• Daily mode (default setting): when the light is off, press the power button three times to access directly to the TURBO.
• Tactical mode: when the light is off, press the power button three times to access STROBE directly.

To select the desired user mode:
1. Make sure the light is turned off.
2. Loosen the tail cap.
3. Continue to hold the power button while tightening the tail cap simultaneously.
4. After tightening the tail cap, the LEDs will indicate a selected user mode by flashing once for daily mode
or twice flashing for tactical mode.



On off
On: when the light is off, press and hold the power button for approx. 1 second to turn it on.
Off: When the light is on, briefly press the power button to turn it off.

Brightness levels
When the light is off, press and hold the power button after turning on the flashlight to cycle through the following levels of brightness:
ULTRALOW - LOW - MID - HIGH - TURBO. Release to select the desired brightness level.
(This access has a mode memory. When reactivated, the flashlight will automatically access the stored brightness level previous one.)

Direct access to ULTRALOW
When the light is off, press the power button twice to directly access ULTRALOW.

Temporary access to TURBO
When the light is on, press and hold the power button to momentarily access TURBO.
Release to return to the previous brightness level.

Special modes (STROBE / SOS / BEACON)
When the light is on, press the power button three times to enter STROBE mode.
When STROBE mode is active, long press the power button each time to cycle through the following special modes:
When one of the special modes is active, briefly press the power button to exit the special modes and turn off the light.

ATR (Advanced Temperature Regulation)
Integrated ATR technology adjusts the output of E4K based on working conditions and the surrounding environment to maintain performance






The Nitecore E4K is a compact torch that reaches 4400 lumens in TURBO mode. If tried closely, lighting a white wall, then tint has a dominant greenish that disappears when we illuminate in the distance.

The beam is alluvial in nature, however allowing a good one medium distance lighting. To the eye I do not see any significant PWM in any of the 5 modes. The beginning of the spill from the walk is adjacent to the feet.


The Runtimes were done indoors with an ambient temperature of around 18 °C using the 5000 mAh Nitecore 21700 battery in equipment.

I want to clarify that the values expressed by the graphs must be taken, above all, as a reference because they are made with different means and environmental conditions
from those used in the laboratory.


The first test was made by placing the Nitecore E4K in "TURBO" mode (4400 lumens). After about 21 seconds a descent takes place
sudden brightness that settles at 24 seconds on 3040cd. The autonomy with the 21700 5000 mAh battery is truly remarkable.





The first 10 minutes of the same test:


The second test was done by putting the Nitecore E4K in "HIGH" mode (1050 lumens). The graph is very similar to that of the mode TURBO after the first step-down.

I noticed, in particular, the intervention of the ATR system (Advanced Temperature Regulation) for almost all the duration of the test.





Let's see the TURBO and HIGH curves together:



The third test was done by putting the Nitecore E4K in "TURBO" mode (4400 lumens) with the help of a small fan. From the graph yes he deduced that the first drop in intensity is

similar to runtime without ventilation while Nitecore's ATR system subsequently intervenes.

Let's see the TURBO and TURBO FAN curves together:











The Nitecore E4K is a powerful flashlight with its maximum 4400 lumens but at the same time a compact EDC with excellent autonomy. As can be seen from the graphs, the "HIGH" level

has a duration of over 3 hours as per Nitecore specifications. Another advantage, which is being lost in recent times, is the possibility of using different batteries to operate the E4K.

Good interface of use, even if you need a few minutes of learning, and well-spaced available levels (complete with memory) also considering the possibility of direct access to the

ULTRALOW, TURBO or STROBO level. Finally, the sales package is complete with all the accessories to use the torch immediately. I just have to recommend the Nitecore E4K although

I hope in the near future to see the same torch for sale but with a warm or neutral tint. Thanks for reading the review.


Edited by: roma58 on 03/06/2020 - 03:25
Last seen: 1 month 1 day ago
Joined: 02/05/2018 - 09:40
Posts: 528

Thank you for good review. The light seems like an all out flooder, XPL-HIs 3D would be perhaps interesting choice for more distance. If Hank made a 21700 fueled D4V2, that would be on my must have list.

roma58's picture
Last seen: 17 hours 11 min ago
Joined: 01/09/2016 - 19:38
Posts: 205
Location: italy

Dioda wrote:
Thank you for good review. The light seems like an all out flooder, XPL-HIs 3D would be perhaps interesting choice for more distance. If Hank made a 21700 fueled D4V2, that would be on my must have list.

I agree with you, however I liked it also considering that it is a very compact multiled.
Last seen: 4 hours 10 min ago
Joined: 09/22/2015 - 20:38
Posts: 982
Location: Prescott Az

Thank you for your comprehensive and valuable review. I ordered this item as soon as it was announced  on the Nitecore website, because I was excited to discover that a major manufacturer that markets lights at law enforcement decided that normal people were finally  ready for 4,000 lumens in this size light.

The user interface is different, but two things that I like a lot are that max mode (turbo) is memorized in the normal mode selection queue, and press and hold for instant turbo from On.

The protected Nitecore USB ported 21700 battery fits in Xtar SC1, SC2, and X2 chargers, but is too long for the VC4, VP4 and VC4S.

Unprotected 21700 cell  works great after a spring is soldered to the cell.

Select modes from On by double click and hold.

Flashing voltage reading is much, much easier to accomplish than in the TM9K.

Again, thank you!

Rev 22:15

Last seen: 2 days 19 hours ago
Joined: 08/17/2021 - 23:38
Posts: 1

There is a new version on the E4K that uses a 2-Stage Switch and changed the UI. It has the same name, there is no visual difference with the old version and i think it came out in 2021.

Go to the official E4K page to see the difference :