Author Topic: Review: Nitecore MT21A (XP-E2 R2 | 2 x AA)  (Read 11159 times)

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Offline _the_

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Review: Nitecore MT21A (XP-E2 R2 | 2 x AA)
« on: October 13, 2013, 07:51:09 PM »
Nitecore MT21A (XP-E2 R2 | 2 x AA)

This flashlight was provided for review by

Reviewer's Overall Rating: ★★★★☆

Battery: 2 x AA (Alkaline, NiMH, Lithium primary)
Switch: Tail switch, Forward clicky
Modes: 6: Turbo, High, Med, Low, SOS, Strobe (in 2 groups)
LED Type: XP-E2 R2 (CW)
Lens: Glass, AR coated
Tailstands: No
Price Payed: Review sample. Retail price $30.99
Date Ordered: September 2013


  • Good build quality
  • Easy to use (UI is good both for beginners and experts!)
  • Throws pretty well for a 2xAA light
  • Current regulated -> No PWM on any mode
  • Good regulation & runtime
  • Well spaced modes (the low could be even lower for my taste though)
  • Good thermal characteristics - temperature raised only to maximum of 46C during a 2h run indoors (ambient temp 23C)
  • Unibody design in head
  • Lightweight
  • Flat bezel
  • AR-coated lens
  • Good lanyard (not the usual crap found in budget lights)
  • Comes in a nice retail box, lanyard included, good for gifting!
  • Doesn't tailstand (but on the other hand: the tail switch is very easy to use in this design)
  • Low mode could be lower
  • Not available as NW
  • No clip
  • Everything heavily glued -> not easy to mod
Features / Value: ★★★★★

The light comes in a retail box which contains the light itself, lanyard, two extra O-rings, spare boot, warranty card, and a manual (in English).


This light has four well spaced, current regulated modes. Blinky modes are there, but only in User-Defined Mode group (see explanation below).

UI is good, divided in two mode groups which can be selected by tightening or loosening the head:

1) Turbo Mode (head tightened)

Simple "no-nonsense" functionality: Forward clicky switch allows you to have full power either momentarily (press lightly & keep pressed) or constantly (press until clicks, release). Note that there are no other modes in this group => No danger of changing modes accidentally!

Turbo mode has an automatic step-down feature: If the turbo mode is used over 3 minutes, the light steps down slightly (~30lm less, still higher than High mode) to prevent overheating. If you still want to continue with turbo, you can go back to turbo with turning light off and on again.

Please don't let the mode name mislead you: This is not a hyper super turbo which should not be used for a long time. In fact this is my most used mode with this light, giving constant 190lm OTF without overheating or any other problems.

2) User-Defined Mode (head loosened)

Five modes, with working memory. Just press the forward clicky tail switch and the light always starts on the last mode used.

To change modes, turn light off and on in 2s period. Modes are changed in the following order: High, Med, Low, SOS, Strobe.


I really like this UI, since it gives me the best of both worlds: Easy access to full power and many lower (and blinky) modes with memory. You can think this light as a two mode light: Just tighten the head and select between those two modes. My preferred setup is "Turbo + Low", but for example security guards might find "Turbo + Strobe" very useful.

Similar kind of UI has been seen in 4sevens Quark X AA2 Tactical, but Nitecore has a great advantage: Configuring the User-Defined Mode is easy. Almost as easy as using a normal 5-mode light, but with forward clicky.

Or when loaning this light to a novice user, just tighten the head and say that it's one mode light. ;)


Value for money: Good!


Design / Build Quality: ★★★★☆

Design is very simple, nice, and easy for eyes. Reminds me of Fenix E21, but is significantly thinner and lighter.

The anodization is very good overall. A bit glossier than E21, but doesn't have a "painted" feeling. Texts are crisp and clear. Head doesn't have knurling, but it didn't bother me, not even when changing between modes.


Bezel is flat and emitter well centered. Just like I want 'em!


Lens is glass and clearly AR-coated:


Let's see some details..

Tailcap taken away. Here we can see the well lubed, anodized, square threads and thick O-ring. Tailcap has a hole for attaching the lanyard.


The spring at tailcap is thick and of good quality. The switch is kept in the place with a retaining ring and a lot of locktite! I didn't get it open with any available tools. It's a bit strange since there was even a spare boot included..


Head taken away. Threads are not anodized on this side, but still well lubed and of good quality. Note also the thick walls at this part of light.


Three basic parts of the light: Body, head, and tailcap.


Another pic showing them in the right order: :)

That is as far as an ordinary user should disassemble the light.


..but I had to open the head to see how the reflector design & thermal management are in this light..


After trying several methods, and quite much time, I finally managed to open the head, and this is what I found.. Lots of red locktite!


After I got over that shock, I saw a pretty sight: No pill, but uni-body design with thick platform under the star. Star was mounted with good amount of thermal paste (not too much) and the ground path to driver was secured with third lead screwed and soldered to the body.


Other side of the head reveals the reason for third lead: The driver is glued in!! [I didn't want to break it, at least not before beamshots & measurements, so it is still intact]

Note also the reflector. It's made of aluminum and has side walls which keep it in place & well centered.


The included lanyard is long, round-shaped & thicker than normal, and has tightening device in between. It must be one of the best lanyards I have seen in budget lights!



Some measurements:

Length: 157mm (including the protruding tail switch, 153mm body only)

Head diameter: 25.5mm

Body diameter: 18.7mm

Tail diameter: 21.5mm

Tailcap protrusion: 4.0mm

Lens diameter: 23.0mm

Lens thickness: 1.5mm

Reflector diameter: 22.7mm (inner dia: 19.9mm)

Reflector depth: 18.1mm

Weight: 132g with 2 cells (= ready to use), 70g without (compared to E21: 150g/98g)


..and here's some pictures confirming the measurements:


Compared to Fenix E21: (Note how much thinner MT21A is!)



And the bottom line in the quality: Nothing to complain. Except the non-moddability due extensive use of locktite (shouldn't bother "normal" users).


Battery Life: ★★★★☆

Good! Two batteries and good mode arrangement with pretty low low will allow very long runtimes.

I measured the tailcap current and got results of 2.0A on Turbo, 0.53A on High, 0.21A on Med and 0.04A on low.

This would give only about 1h runtime on Turbo, but the step down helps a lot, enhancing the runtime nearer to 2h on Turbo.

Calculated runtimes for other modes are: 5h on High, 12h on Med, and over 60h on low!

I would like to see yet another low-low mode with around 1lm (or 0.005A), which would give us around 500h runtime.


Light Output: ★★★★☆


Runtime graph: (Eneloop XX 2500mAh cells)

The first almost three minutes are on turbo, rest of the graph on stepped down level (still higher than high). This runtime test was done indoors, with ambient temperature of 23C, without any additional cooling. This light seems to be well regulated and handles the heat very well.

This light has kind of a low voltage warning (light flickering with very low level), which kicked in at about 1:51.


Let's try again, for first 10 minutes, forcing the turbo on:



The initial light output on Turbo was 256lm and ANSI-readings (OTF, after 30s) were:

- 224lm on Turbo

- 190lm on stepped down Turbo

- 127lm on High

- 65lm on Med

- 14lm on Low


Those measurements do match pretty well the advertised values, except on the turbo, where Nitecore might have taken the initial value(?)


Measured throw is 11kcd / 200m (compared to E21: 6kcd / 150m)


White wall beamshots (1/100s, f/5, ISO80, WB: Daylight)

Turbo (vs. E21 High)


High (vs. E21 High)


Med (vs. E21 Low)


Low (vs. E21 Low)


Turbo (vs. E21 High) again with reduced exposure (1/400s):


Beam patterns:


Beam angles:


Outdoor beamshots:

 Coming soon.


Summary: ★★★★☆

Well designed & built AA-powered light that can be safely given to anyone (even to my mother!). No worries about Li-Ion cells, no overheating (even on Turbo mode), enough power & throw, easy UI, ... What's not to love? [Glue?]


Verdict: Recommended!  [Not recommended for modders though]


The End (pun intended):


Thanks for reading & watching. Hope you enjoyed the review!
« Last Edit: October 14, 2013, 05:30:54 PM by _the_ »

Offline _the_

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Re: Review: Nitecore MT21A (XP-E2 R5 | 2 x AA)
« Reply #1 on: October 13, 2013, 07:56:22 PM »
Good news: The banggood representative liked my review on BLF so much that he decided to gives out ten (10) Nitecore MT21As for only $26 with coupon code bgf108.

I'll publish this coupon at BLF later today, so be quick if you want to get one of those 10. They'll be spent quickly after publishing there, I think.. ;)

Offline MRsDNF

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Re: Review: Nitecore MT21A (XP-E2 R5 | 2 x AA)
« Reply #2 on: October 13, 2013, 08:25:06 PM »
Fantastic review _the_. Thanks also for sharing the coupon here.  :)
When the big picture is to big, look for a point you can start at and build from there.

Offline gords1001

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Re: Review: Nitecore MT21A (XP-E2 R5 | 2 x AA)
« Reply #3 on: October 13, 2013, 08:37:04 PM »
just a thought,  the switch retainer isn't a left hand thread is it? gluing it does seem odd if they supply a switch boot...

Thanks for the review, hoping to see many more added here old and new.

Offline JohnnyMac

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Re: Review: Nitecore MT21A (XP-E2 R5 | 2 x AA)
« Reply #4 on: October 13, 2013, 09:12:08 PM »
Like most Nitecore lights, this one seems awesome! Thanks for the great review!

I'm with you on the lower low being needed but this should provide more than ample output for most users and best of all, it looks like a flashlight should look. For that price you get a far better light than the new 2*AA Mini Maglight Pro. The regulated current and consistent output spanks it hands down.
« Last Edit: October 13, 2013, 09:12:35 PM by JohnnyMac »

Offline Spasmod

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Re: Review: Nitecore MT21A (XP-E2 R5 | 2 x AA)
« Reply #5 on: October 13, 2013, 09:44:35 PM »
Thanks for a fantastic and in-depth review _the_, and for persevering to get the head removed. I like what they have done with this one! seems like a very good light and comes in at a very reasonable price too :)

Offline hammerheel68

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Re: Review: Nitecore MT21A (XP-E2 R2 | 2 x AA)
« Reply #6 on: November 12, 2013, 04:13:47 AM »
Very Good Review !  I've been debating on getting either this light or the mt1a-single aa version, and I haven't pulled the trigger yet.  My normal default is to go with a Single aa, but this review makes the decision even harder.

Offline hammerheel68

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Re: Review: Nitecore MT21A (XP-E2 R2 | 2 x AA)
« Reply #7 on: December 09, 2013, 12:36:39 AM »
Well; Battery Junction helped me make my decision; they ran a "Black Friday" week-end Sale, and I got the MT21A for Less than 25 Bucks!!  It just arrived yesterday, and it is outstanding, as advertised.  Thanks so much for your Great Review; I would never have considered this light if not for your Outstanding work.  Thanks Again !!

Offline Spasmod

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Re: Review: Nitecore MT21A (XP-E2 R2 | 2 x AA)
« Reply #8 on: December 09, 2013, 12:44:31 PM »
That's great news Hammerheel! I can't thank our review contributors enough, it's good to see their efforts are helping you guys make the right choices.

Please let us know how you get on with it after some prolonged use Hammerheel, it's always very nice to see follow-up thoughts through the test of time :)

Thanks again for a great review _the_