# NiteCore D20 Review - 2xAA - RUNTIMES, BEAMSHOTS, DETAILED PICS and more!



## selfbuilt (Oct 24, 2008)

*Warning: Picture and text heavy!*

_*Reviewer's Note: *The NiteCore D20 was provided for review by Edgetac (NiteCore). _

The NiteCore D20 is the latest offering in the piston-drive "SmartPD" family from Edgetac (NiteCore). Although a lot of the basic design and circuit functioning is similar to the 1AA D10, this new 2AA model features some significant build differences. 

The main distinguishing features of all the NiteCore Smart PD lights is their simple continuously-variable interface, and innovative McGizmo "piston drive" design that doesn't use a clicky switch. For a comparison to the 1AA D10, please see my earlier reviews:
NiteCore D10 & EX10 Reviews: RUNTIMES, BEAMSHOTS, COMPARISONS & more!
NiteCore Golden Dragon Plus D10 & EX10 Reviews: BEAMSHOTS, RUNTIMES, etc.







The light comes in a sturdy hard cardboard box with magnetic closing flap. The pocket clip was already attached. Along with the light and clip come a manual, warranty card, good quality wrist strap, extra o-rings, extra clip screws, and a mini-Allen key for the clip screws.

Approximate retail price: $70 USD










Here is how it compares to the competition:





From left to right: Duracell 1AA alkaline, NiteCore D10, NiteCore D20, Fenix L2D, Olight T25, ITP C8 Tactical, JetBeam Jet-I PRO EX V2.

D20 Weight: 109.3g
D20 Dimensions: Length: 154.0mm x Width: 25.0mm (head), 23.2mm tail (without clip)

The obvious build difference on this 2AA version is the heft – the light is surprisingly bulkier than the 1AA model. oo: Although well balanced and comfortable in the hand, this light is definitely one of the most substantial in the 2AA class. The bezel is wider than the 1AA model, and the head unit has heatsinking fins at its base.










One of the most obvious changes is the introduction of the clip at the tailcap, with its stainless steel clip holder and retaining ring. Edgetac includes a mini Allen key, but a 3/32nd hex screwdriver will also fit. The tailcap retaining ring should reinforce the aluminium in this area, and increase long-term durability. :twothumbs

Unlike the 1AA version, the piston cannot be removed from the open end of the body tube (i.e. near the head) – if you want to access the piston, you need to remove the clip and unscrew the piston opening retaining ring (you’ll need a pair of tweezers or snap-ring pliers). Not that there is any real reason to do so, unless you want to check the lube status of the piston o-ring.










As you can see in my disassembled pics above, NiteCore is still using a lot of the high-viscosity blue-colour lube on the o-rings. :shrug: Although not causing a problem on this sample, a number of the D10/EX10 lights have issues with “sticking” pistons with this lube. The problem is easily solved after disassembly by a quick wipe off of excess lube, or addition of lower viscosity lube, like PTFE (i.e. Teflon, like from the Radio Shack Precision Oiler)

UPDATE: I find the PTFE lube wears off after a couple of weeks, leading to a "clinking" sound when the bare metal piston meets the aluminum body. I am now trying a little of the more viscous Nyogel 760G, which seems to be working well. Wouldn't normally be a problem to just re-lube periodically, but having to disassemble the clip and retaining ring on the D20 each time means you need to have tools with you. 

The purpose of this re-design quickly becomes apparent – the light has a fully functioning tailcap lock-out feature now. :thumbsup: Previously, you could partially lock-out the light by significantly unscrewing the head – making it harder for the piston to engage. But this was not a true lock-out – the piston drive could always be engaged with enough force. Now, the piston can only travel so far up the battery tube, so once you unscrew the head pass a certain point, the light cannot be engaged. Well done.

Fit and finish is excellent on my samples - lettering is very clear and sharp, and anodizing is flawless. Note the knurling on all the NiteCore Smart PD light is more aggressive than pretty much any other Chinese light maker I've seen. Still not quite as severe as Surefire lights, though.










The head/reflector has been redesigned from the D10/EX10/NDI, with a wider and deeper reflector with a new stainless steel bezel ring. Despite this deeper reflector, throw is not increased as much as you might expect (scroll down for a throw/output comparison). My sample came with a Cree Q5 emitter, as you can see.










I've opened the head up to show you the insides - it comes apart fairly easily by unscrewing the bezel retaining ring (i.e. pressing on it firmly with a soft cloth). You can see the spring on the light engine. It all fits together well, so there's no real adjustment you can make. The reflector has a nice groove/lip to help hold the o-ring, so re-assembly is a snap. 

*Piston Drive & User Interface*

Please see my NiteCore D10/EX10 review for a detailed discussion of how the basic Piston Drive mechanism and UI works. 

Simply put, the batteries sit inside the piston tube, and switching occurs entirely in the head (i.e. the current path is through the piston sleeve and not the body). The contact ring in the head is spring-mounted, and in combination with the MCU can produce different modes and features depending of degree of force applied to the piston. This innovative design also allows you to utilize the light in a couple of different ways (i.e. as both a "twisty" and "clicky" light).

The UI is actually quite straightforward and easy to use. For a good instruction on how to use it, see 4sevens’ D10 video guide here:
http://www.youtube.com/watch?v=irqhuV8Xo_A

So what’s new with the circuit? One welcome change is that auto ramping in the reverse direction after using the shortcuts to Min or Max now works. :twothumbs On the 1st generation SmartPD lights, you needed to press and release and press again to get it to start ramping in the reverse direction after using a shortcut (double-click for Min, click-hold for Max).

Another change has been to increase the number of discrete output states from 100 to 256, according to NiteCore. As a result, I would have expected a longer ramping time, but NiteCore has kept the total ramp length down to about 6-7secs, which is just a second longer than the D10/EX10. 






If anything, ramping is even more visually-linear now than it was before. But I find I rather miss the slower initial ramp at the lowest outputs (i.e. the D10 spends more time there, proportionally-speaking).

*Comparison Beamshots*

Both lights are on 100% on Sanyo Eneloop (~2100mAh), about 0.5 meters from a white wall. 














As you can see, the beam profile is quite different. Gone on the D20 is the typical dark Cree ring around the hotspot – instead, you can see the D20 hotspot is a lot broader and more diffuse. This relative “defocusing” of the hotspot gives you less throw than you might expect for a bigger reflector. Overall spillbeam width is slightly narrower as well now.

For detailed comparison to its class of 2AA lights, I’ve rounded up the usual suspects:





From left to right: Duracell 1AA alkaline, NiteCore D10, NiteCore D20, Fenix L2D, Olight T25, ITP C8 Tactical, JetBeam Jet-I PRO EX V2. Not shown is the new Fenix LD20.

All lights are on 100% on 2X Sanyo Eneloop (~2100mAh), about 0.5 meters from a white wall. 




























As you can see, the beam profile is again quite different from the typical Cree pattern. Personally I rather like this more diffuse hotspot, but those looking for greater throw will be disappointed.

*Testing Method:* All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for the extended run Lo/Min modes which are done without cooling.

Throw values are the square-root of lux measurements taken at 1 meter from the lens, using a light meter.

*Throw/Output Summary Chart:*






On the face of things, it looks like the D20 is definitely brighter on max than the D10 – as you would expect for 2AA light. As previously mentioned, throw is increased, but not by a large margin.

In comparison to the its 2AA brethren, the D20 is toward the high end in terms of max overall output – but my Fenix L2D and LD20 are both brighter. However, the D20 is capable of the lowest output level of any of my 2AA lights. :thumbsup: Throw of the D20 is also the lowest of the 2AA lights. 

*Output/Runtime Comparison:*














There are no surprises here – the D20 is a consistently good performer at all output levels.  






*UPDATE:* I've done a non-lightbox runtime of the D20 on Low on duracell alkalines and got just over 10 days of continuous runtime. oo: 

Among the continuously-variable lights, the D20 performance is very consistent with the ITP C8 lights, and more efficient than the JetBeam Jet-I PRO EX V2. However the D20 is not as bright on max or as efficient overall as the current-controlled Fenix lights (the latter point is to be expected on a PWM-based light). 

*Potential Issues*

The only significant issue I’ve observed in testing is the amount of pressure needed on the piston to keep the light ramping smoothly. Even after cleaning and re-lubing, the force required is definitely more than my D10/EX10 lights. To be certain, the original SmartPD lights required some getting used to in this regard, but this one is definitely even more of a challenge.

As for grip, I like the new body design for over- or under-handed use (i.e. thumb on the piston). Although this design includes some built-in finger grips for a cigar hold, I think you would find it difficult to balance and use the light that way (especially for ramping or rapid clicks). 

Haven’t had a chance to really test out the clip in actual usage, but I wonder how secure those screws will hold it the long-term. Time will tell how well this feature holds up.

UPDATE: Proper level of piston lubrication can also be an issue - which requires the use of tools to remove the clip and retaining ring to re-lube. I'm currently trying Nyogel, since I find the PTFE wears off after awhile. 

*General Observations & Preliminary Conclusions*

The D20 is a welcome addition to the NiteCore SmartPD family of lights. I’ve always had a soft spot for 2AA lights. 

In terms of circuit design, the D20 is definitely an incremental improvement. The automatic reverse ramping and increased output states are positive bonuses. Same goes for some of the new build differences - the pocket clip, stainless steel retaining ring, and piston lock-out features are all useful new additions. I imagine we will start seeing these features in the other members of the SmartPD family as well. :thumbsup:

Overall, I like the sturdy design of the D20 (except for stiffer piston feel). But one of my favourite aspects of the D10/EX10 series was their slim-lined design. Those lights were among the smallest lights of their class, whereas the D20 is one of largest. :shrug: If you are looking for a similarly minimalist 2AA light, you will have to look elsewhere. 

The reflector design is interesting – this is one of smoothest Cree beam profiles I’ve seen. But unlike shallow reflectors (which smooth out rings but produce a wide and dim spillbeam), this deep reflector produces a more even (but narrow) spill output. I will need to play with it more before deciding how I like it – but my experience with the LiteFlux LF5 (which has an even narrower spillbeam) tells me you can get used to just about anything. For a general purpose light, removal of the dark Cree rings is a definite plus – just don’t expect a big thrower here.

As always, you need to assess what features matter to you in any given class of light. Now that a number of 2AA lights are on the market, I plan to do a round-up comparison review of this group soon. Stay tuned …


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## adirondackdestroyer (Oct 24, 2008)

Great review Selfbuilt. I received my D20 around a week ago and have been waiting for your review (as you know ). 
My only complaint is that I think it ramps up too quickly at the very beginning. It ramps down much slower than it ramps up. Or at least that's what my eyes are telling me. 
Are you planning on doing a runtime test on the lowest setting? I'd love to know how long this badboy would run on the lowest setting with two Energizer Lithiums. I'm guessing 165 hours or so.


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## simple (Oct 25, 2008)

Great review as usual. Must resist...


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## EngrPaul (Oct 25, 2008)

The D20 is the classy indoor performer of the group. Definitely worth showing off to friends and enjoying around the house on a regular basis.

As always, I appreciate the excellent pictures, feature description, comparison to other similar lights, and accurate runtimes.


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## gswitter (Oct 25, 2008)

selfbuilt said:


> The purpose of this re-design quickly becomes apparent – the light has a fully functioning tailcap lock-out feature now. :thumbsup: Previously, you could partially lock-out the light by significantly unscrewing the head – making it harder for the piston to engage. But this was not a true lock-out – the piston drive could always be engaged with enough force. Now, the piston can only travel so far up the battery tube, so once you unscrew the head pass a certain point, the light cannot be engaged. Well done.


Interesting.

This change could also address a minor issue I've had with the McLux III PD's. There has to be enough of a gap between the exterior of the piston and the interior of the body to account for the (partial/exposed) width of the o-ring - if the gap is too narrow the o-ring will keep the piston from sliding easily. But this leads to a larger gap than necessary around most of the piston, and it feels as though the piston skews slightly when pressed. With this design change the larger gap would only have to run the small length of the body that the o-ring travels, and the gap could be tightened down for the rest. That's a nice enhancement, and while it does add one more part to the light, the change seems otherwise benign. Well done, indeed.


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## jimmy1970 (Oct 25, 2008)

I don't think Selfbuilt is going to polish a turd just because he has the lights provided by the dealers. These reviews must be a right pain to do. They would take forever. I know I couldn't be bothered...

What I can't work out is why the D20 is so long?? The D10 is a nice size, if they made the D20 just 1 AA longer in length than the D10, I would buy one. By the look of those photos, the D20 is longer than my L2DQ5 with a clicky. 

jr/


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## Burgess (Oct 25, 2008)

to SelfBuilt --


Another fine review here !


Thank you for your time, effort, and dedication.


:goodjob::thanks::twothumbs

_


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## Closet_Flashaholic (Oct 25, 2008)

Thank you for the review.

What I am having a difficult time with is the large difference in runtimes at Med-High for the D20 vs. the Fenix..... The fenix runs for 1 hour more and it's brighter!.... They are both using Q5's.....

I like the D20 it seems well built and its UI, but the diminished runtime is holding me back.. I will have to see..


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## phantom23 (Oct 25, 2008)

Fenix uses current regulator which is more efficient than PWM in D20.

Selfbuilt, which T25 you have (looking forward to graphs on lower modes)?


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## selfbuilt (Oct 25, 2008)

Thanks for the support everyone! :grouphug:



EngrPaul said:


> The D20 is the classy indoor performer of the group. Definitely worth showing off to friends and enjoying around the house on a regular basis.


Yup, the beam actually reminds me more of an SSC pattern than a Cree, thanks to that new reflector.



adirondackdestroyer said:


> My only complaint is that I think it ramps up too quickly at the very beginning. It ramps down much slower than it ramps up. Or at least that's what my eyes are telling me.


No argument here - my ramping graph shows exactly that for the low-to-high ramp. I also find it moves through the low levels too quickly - but, technically speaking, it is actually more visually linear than the old ramp. 



jimmy1970 said:


> What I can't work out is why the D20 is so long?? The D10 is a nice size, if they made the D20 just 1 AA longer in length than the D10, I would buy one.


Yeah, that's why I pointed it out in my review. I too would probably prefer a slim-lined 2AA D10-type light.



Closet_Flashaholic said:


> What I am having a difficult time with is the large difference in runtimes at Med-High for the D20 vs. the Fenix..... The fenix runs for 1 hour more and it's brighter!.


As mentioned by phantom23, Fenix's current-controlled circuit (with its limited number of outputs and lack of true low) will always be more efficient at medium settings. Note also that my Fenix LD20 seems considerable less efficient on maxium than my L2D ... not sure why, and haven't had time to do the medium and low modes on the LD20 yet. Stay tuned ...



phantom23 said:


> Selfbuilt, which T25 you have (looking forward to graphs on lower modes)?


It's the regular version. Haven't had a chance to do runtimes yet, it's in the queue.


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## selfbuilt (Oct 25, 2008)

Just updated the review with some detailed pics of the light engine










Note that I'm not able to adjust the focus of the reflector - it all fits together pretty securely (i.e. the reflector stops when it hits the brass pil).


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## Imothep (Oct 25, 2008)

selfbuilt said:


> The reflector design is interesting – this is one of smoothest Cree beam profiles I’ve seen. But unlike shallow reflectors (which smooth out rings but produce a wide and dim spillbeam), this deep reflector produces a more even (but narrow) spill output.



I can't agree with that in my case, my D20 is quite ringy compared to my old Fenix L2D Q5. 

D20:






L2D Q5:






Overall I'm a little bit disappointed, it's not as bright as my L2D, throw didn't improve, beam is quite yellow compared to the slightly purple fenix, and it's quite big and heavy.

Anybody in Vienna/Austria who wants to have it?


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## phantom23 (Oct 25, 2008)

Many people like warmer tint.

About the beam - I've got three NDI's and each of them has different beam. One was very ringy, second one was perfectly smooth and third one was somewhere between them.


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## selfbuilt (Oct 25, 2008)

Imothep said:


> Overall I'm a little bit disappointed, it's not as bright as my L2D, throw didn't improve, beam is quite yellow compared to the slightly purple fenix, and it's quite big and heavy.


I hear you - beam tint is variable, but mine is certainly a premium white. My results also show that output and throw is slightly less than the Fenix, and the D20 is definitely heavier.

But as for the beams, I think the reason mine seems less ringy is that the emitter is actually slightly de-focussed on mine (i.e. a bit of a donut is visible at really up-close distances). But I'm unable to adjust it since the reflector meets up perfectly with the brass pill - I would need to desolder the mini-star and shim it underneath if I wanted to get the emitter higher into the reflector. 

Note as well that mine is even less ringy in real life than the beamshots look (JPEG compression tends to enhance ringiness) - my L2D has a pronounced dark ring in comparison in actual use. My D20 really does seem more SSC-like to be than Cree-like overall. :shrug:


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## I came to the light... (Oct 25, 2008)

Thanks for the review . 

My first high-end flashlight purchase was a L2D Q5. I'm amazed that it is still on top, and by such a large margin! Although the fact that its "upgrade" doesn't perform as well is alarming...


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## Federal LG (Oct 25, 2008)

Nice review selfbuilt! 
Thanks for posting it.

I need a new 2xAA... And this review helped me a lot!

Just one question: *Which 2xAA light has more throw ?? *


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## phantom23 (Oct 25, 2008)

1. Fenix TK20
2. Olight T25
3. Eagle-Tac P10A2


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## EngrPaul (Oct 25, 2008)

Federal LG said:


> Just one question: *Which 2xAA light has more throw ?? *


 


phantom23 said:


> 1. Fenix TK20


 
AGREED! :thumbsup:


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## Jarl (Oct 25, 2008)

I came to the light... said:


> Thanks for the review .
> 
> My first high-end flashlight purchase was a L2D Q5. I'm amazed that it is still on top, and by such a large margin! Although the fact that its "upgrade" doesn't perform as well is alarming...



Agree with everything in that post. It's probably not a bad idea to pick up another couple of L2D's; I mean, they don't excel in anything really, they're not the smallest, not the brightest, not the toughest. However, when the sh*t hits the fan I can't think of any light I'd rather be holding.....

Looks like I better grab one for a BOB


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## Axion (Oct 25, 2008)

Excellent review as usual. 

My L2D Q5 has the heavy OP reflector and as a result a VERY smooth beam, the smoothest of any of my lights by far, but it does tend to be lacking in throw. I was hoping with it's larger reflector the D20 would be better then the L2D in that respect.


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## jdong (Oct 25, 2008)

Call me crazy but I think the tint on the D20 looks better, though the L2D seems brighter at that distance.


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## selfbuilt (Oct 25, 2008)

phantom23 said:


> 1. Fenix TK20
> 2. Olight T25
> 3. Eagle-Tac P10A2


I don't have the P10A2, but can confirm the TK20 has the best throw of the class. Still need to do runtimes on the TK20 as well ... it will also be included in my eventual 2AA round-up.


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## PlayboyJoeShmoe (Oct 26, 2008)

THANK YOU for doing the review!

I KNOW it's a TON of work!

I know there is no WAY I could do it!

So THANKS!


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## hwoont64 (Oct 27, 2008)

wonder if the head is compatible with the ex10 or the d10


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## selfbuilt (Oct 27, 2008)

PlayboyJoeShmoe said:


> I KNOW it's a TON of work!


Thanks PJS. FYI, I am planning to shorten the length of my reviews going forward, given the workload involved with them (just too busy at work these days). I'll also be doing less low mode runtimes on primary lithium cells (CR123A/L91), as I am burning through them at an alarming (and expensive) rate! :candle:



hwoont64 said:


> wonder if the head is compatible with the ex10 or the d10


No, they are different diameters and will not thread on to each other


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## StarHalo (Oct 27, 2008)

selfbuilt said:


> Haven't had a chance to do runtimes yet, it's in the queue.



I know you don't normally do minimum output runtimes, but if ever there should be an exception, this would be it; The main selling point for a 2xAA light, for me anyway, is maximum runtime. I'd really like to see which of these lights could win a moon mode marathon - I know the L2D is the current reigning champ at ~77 hours, and though the JetBeam can go far lower, it probably doesn't have the efficiency to go the distance. I'd wager the D20 is the one newcomer that stands the best chance of beating the Fenix..

Even if you just do a basic "To 50%" time list without a chart, this would be some very helpful info.


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## selfbuilt (Oct 28, 2008)

StarHalo said:


> I know you don't normally do minimum output runtimes, but if ever there should be an exception, this would be it; The main selling point for a 2xAA light, for me anyway, is maximum runtime.


You make a good argument StarHalo ...

...but I'm starting to think that minimum mode runtimes are just too problematic. Now that we are starting to see lights with really low output modes, the problem of Vf variability seems to be becoming huge at these outputs. I'm seeing variability in runtime reports on the order of > 3-fold for some lights on low settings than aren't even as low as the ones we are discussing here. And my discussions with various light makers confirms that this is not an isolated problem.

Simply put, it's looking like low Vf lights are running at considerably higher drive currents than high Vf ones for many circuits on low. Although this effect is often negligible at higher outputs, at really, really low ones it wrecks havoc on runtimes. Without a wide range of samples to test, it's impossible to know how representative my one specimen would be.

Honestly, I could easily imagine the range of runtimes being anywhere from 3 days to 3 weeks. One sample point in there is likely to be highly misleading. I think what we really need now is for makers to test high and low Vf extremes, and report the range of results obtained. I expect you'll see days to weeks variation! :sigh:

EDIT: I see Chevro has recently posted D10 and EX10 Min runtimes, where he got ~4.5 days for the D10 on one Duracell Ultra. My D20 has about the same min output level as my D10 cree, so I would expect pretty decent runtime. It won't be the most accurate, but I've just started a Min run of my D20 on 2 regular Duracells in a corner of my closet. At least this way I should be able to tell you when the run stops, +/- half a day or so, since I go into the closet each morning and evening. But please keep in mind that this is just for personal "entertainment" purposes - Vf variability could hugely affect ultimate results.


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## cerbie (Oct 28, 2008)

I was under the assumption that the D20 was a fairly high drive current light (relative to single-digit milliamperes), regardless of output. Is that not the case?


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## selfbuilt (Oct 28, 2008)

cerbie said:


> I was under the assumption that the D20 was a fairly high drive current light (relative to single-digit milliamperes), regardless of output. Is that not the case?


Relatively speaking, I think that's true of many of the current continuously-variable lights - since they tend to be optimized for max outputs and not low. Unfortunately, I'm not able to confirm current draws (even battery draw estimates are problematic with my DMM, since I know it introduces too much resistance).


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## ergotelis (Oct 28, 2008)

I saw that you updated some graphs, but isn't it strange about the runtime of the LD20? It should be about the same with L2d, did they change anything?thanks! 
Would it be possible for you to repeat that test?Or you have done it already?Thanks!


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## selfbuilt (Oct 28, 2008)

ergotelis said:


> I saw that you updated some graphs, but isn't it strange about the runtime of the LD20? It should be about the same with L2d, did they change anything?thanks!
> Would it be possible for you to repeat that test?Or you have done it already?Thanks!


I haven't re-tested the the LD20 on turbo yet, but I did try the same batteries from the LD20 run in the L2D, and got 1:28 runtime, so it looks like that's not the explanation. Just did the Hi mode test on the LD20 and got similar output and runtime to the L2D (but haven't graphed it yet). The Turbo mode could be an anomaly - I'll keep testing and we'll see.

As for the D20, Nitecore has pointed out to me that dimensional stability and overall strength requires a slightly larger build in 2AA format over 1AA. Also, since they designed the light for rugged use, they weren't as concerned about keeping the weight or size down. But they did indicate that they are considering other light designs, so user feedback is welcome.


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## phantom23 (Oct 29, 2008)

Graph curve for LD20 is also slightly different. Maybe they've changed something else than reflector...


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## selfbuilt (Oct 29, 2008)

Just updated the Med-Hi graph with the LD20 Hi (not Turbo) and Olight T25 Level 4 results.







Hit your browser reload if you don't see the traces.

It looks like performance of the LD20 on Hi is not so different from the L2D on Hi. I'll do the Med runtimes later - in middle of a few other lights right now.


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## Kamakazikev24 (Oct 29, 2008)

Hi there, In the real world is there much difference between the output of the D10 and the D20? I would like to know if you feel that the extra size of the D20 is worth it.
Thanks Kam.


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## selfbuilt (Oct 29, 2008)

Kamakazikev24 said:


> Hi there, In the real world is there much difference between the output of the D10 and the D20? I would like to know if you feel that the extra size of the D20 is worth it.


Personally, on standard batteries, I don't think the extra ~20-25% or so output of the D20 makes a big difference in every day use (recall that the D10 is one of the brightest 1AA lights). 

The advantage for me is really the longer runtime of 2AA. This is why I typically recommend 2AA lights for general use by non-flashaholics. 

As for EDC, the extra heft of the D20 probably makes this light most suitable for those who have jobs requiring a heavy-duty light source. Most of us will get by just fine on an 1AA light.


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## Kamakazikev24 (Oct 29, 2008)

Thanks for the advice, I got a D20 today and I will post up my views soon but I have a question. It's been on high for 45 mind on Ni mh 2500 batts and the temp is 48.3 c at the heat sink and 56.1 on the lens. Is that ok? Or will the light be suffering!
Thanks, Kam.


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## Hitthespot (Oct 29, 2008)

Great Review as usual Selfbuilt. Gave me the exact information I needed to make a purchasing decision on a two AA light.

Thanks for your efforts, I know what it takes to complete an in depth review like this.

Bill


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## Kamakazikev24 (Oct 30, 2008)

Hi there! I'am a new member from the UK. First up I would like to thank everyone for all the great information on this site, Its been a big help while trying to find a replacement for my Maglights....

I read some good and not so good reviews and comments on the Nitecore D20, but took the plunge anyway as I liked the look of it, AA batterys are 'free' from work LOL (I'am a signal engineer on the railways) and of all the lights I have seen the clip is actually in the 'right' place!. By that I mean at the END so when I have it in my pocket I dont have a couple of inches sticking out (just not the done thing!)
Why most lights come with the clip halfway up the light I dont know, but it feels really secure when in my pocket as only the clip and the end is showing, with nothing to catch anywhere.

This light is perfectly made, finish is 110% and thankfully the piston switch thingy (technical term) is spot on! Even with rechargable batterys inside there seems to be plenty of feedback and the movement was great straight out of the box.

As for brightness, well I dont have meters so I cant comment and do graphs, but the way it blows my 4 D cell Mag away is Sooo CooL!

Its a perfectly white light, with no rings at all, it throws further than I need it to and when you want to calm it down it goes to a great low level which can be used without starting the dawn chorus!

On two (OLD) AA Ni Mh 2500 Batterys I got Approx 70 mins before she dimmed down, which for the amount of light coming out the business end was impressive.

As I posted before I am still waiting to hear if the temp was OK....

Thanks for the advice, I got a D20 today and I will post up my views soon but I have a question. It's been on high for 45 mind on Ni mh 2500 batts and the temp is 48.3 c at the heat sink and 56.1 on the lens. Is that ok? Or will the light be suffering!

......I looked at it afterwards and saw what I thought was a very straight crack across the emitter base but after looking on here it seems it is made that way and I had not noticed it before.

So Yes, Very happy with my new buy. 

Thanks again for this informative site. Kam.


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## StarHalo (Oct 30, 2008)

Kamakazikev24 said:


> Thanks for the advice, I got a D20 today and I will post up my views soon but I have a question. It's been on high for 45 mind on Ni mh 2500 batts and the temp is 48.3 c at the heat sink and 56.1 on the lens. Is that ok? Or will the light be suffering!



The general rule is the hand test - if you can hold it and it's not uncomfortably warm, then you're fine. Note also that your hand acts as a heat sink, so just the act of holding it helps cool the light.


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## Kamakazikev24 (Nov 4, 2008)

Yeah OK, so after my last post it all starts going downhill! Erratic switching, switching itself off and from high to low in no order  It's been sent back to swap it for a Nitecore Extreme....Hopefully that will be better.
Kam.


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## Lite_me (Nov 4, 2008)

Kamakazikev24 said:


> Yeah OK, so after my last post it all starts going downhill! Erratic switching, switching itself off and from high to low in no order  It's been sent back to swap it for a Nitecore Extreme....Hopefully that will be better.
> Kam.


Yes, some samples will develop this type of problem from time to time. I've noticed it on all my PD lights. All that is usually required is some cleaning and fresh lubing of the piston and the brass switching ring around the pill. Sometimes just a quick twist of one or the other will cure it for awhile. If this kind of routine maintenance is a problem for you, then this light may not be for you. :shrug:


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## kts (Nov 4, 2008)

I love the fact that Fenix old L2D Q5 still dominates :twothumbs


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## PlayboyJoeShmoe (Nov 4, 2008)

One is STILL none, and two (or more) are STILL one!

And I can't really see anything bumping my P2D CE Q5 off my belt!


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## selfbuilt (Nov 4, 2008)

FYI, my D20 has been running continuously for over 7 days now on the lowest output level on a pair of regular duracell alkalines ... still going strong.


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## adirondackdestroyer (Nov 4, 2008)

selfbuilt said:


> FYI, my D20 has been running continuously for over 7 days now on the lowest output level on a pair of regular duracell alkalines ... still going strong.



Unreal! Imagine how incredibly long the runtime on low would be on two Energizer Lithiums (not that I'm asking you to do this. :nana


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## StarHalo (Nov 5, 2008)

adirondackdestroyer said:


> Unreal! Imagine how incredibly long the runtime on low would be on two Energizer Lithiums (not that I'm asking you to do this. :nana



I did some equating and worked out that a D20 should do right around 16 days on Lithiums, and was going to wager Selfbuilt that that's how long it'd go until I remembered he's using alkalines. The alkaline test is probably more real-world, at least.


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## selfbuilt (Nov 8, 2008)

My D20 on Low on duracell alkalines finally shut-off sometime last night ... runtime was somewhere between ... [insert needed :drumroll: icon here] ... 10 days 2 hours and 10 days 7 hours.

So, just over 10 days - very impressive.

:wave:


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## Burgess (Nov 8, 2008)

Gosh ! ! !


Thank you, SelfBuilt, for your time and dedication !


:twothumbs
_


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## PlayboyJoeShmoe (Nov 8, 2008)

:bow: to selfbuilt for such good reviewing!


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## StarHalo (Nov 8, 2008)

selfbuilt said:


> My D20 on Low on duracell alkalines finally shut-off sometime last night ... runtime was somewhere between ... [insert needed :drumroll: icon here] ... 10 days 2 hours and 10 days 7 hours.
> 
> So, just over 10 days - very impressive.



So adding on a 45% difference that lithiums would make over alkalines, that comes out to 14.5 days, nice :thumbsup:


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## Burgess (Nov 8, 2008)

I'm not so sure Energizer Lithium (L91) cells

would perform *significantly better *at such low current levels.


Just a thought.


He'd hafta' test 'em, to find out.


_


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## adirondackdestroyer (Nov 8, 2008)

10 days on two alkalines!!! That's almost 100 hours more than they rate the D20 for on the lowest setting. Freaking awesome!


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## drivie (Nov 9, 2008)

Impressive review of this light. I'm a relative noob with lights but I need a decent one for work (work inside computers a lot). I currently use an incan SF G2 Nitro. The thing eats 123A batteries and sometimes the 60 lumen output washes out tiny text on IC's etc. I love the idea of a 2AA light with variable output.

I am wondering if I'm missing something...I can't seem to locate physical dimensions for the NiteCore lights on the 4Sevens website. Are they there somewhere?

Thanks,

Drivie


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## Lite_me (Nov 9, 2008)

They're right there on the page, under Specifications. Where are _you_ looking?
https://www.4sevens.com/product_info.php?cPath=93&products_id=550


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## drivie (Nov 9, 2008)

Lite_me said:


> They're right there on the page, under Specifications. Where are _you_ looking?
> https://www.4sevens.com/product_info.php?cPath=93&products_id=550




I just looked again and I see them now. I don't know how on earth I missed those specs before. I'm a dork and should be ignored.

Thanks for the response.

Drivie


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## selfbuilt (Nov 9, 2008)

drivie said:


> I am wondering if I'm missing something...I can't seem to locate physical dimensions for the NiteCore lights on the 4Sevens website.


Also posted in the review: 

D20 Weight: 109.3g
D20 Dimensions: Length: 154.0mm x Width: 25.0mm (head), 23.2mm tail (without clip)

You'll note that my measurements (made with a digital caliper) match the reported specs, but weight of my specimen was 10g lighter. Usually, my measurements typically shower larger and heavier results than manufacurer specs.


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## IsaacHayes (Nov 9, 2008)

The LED lottery is still in affect, as my new L2D I had was no brighter than the original L1D I had.... Just to keep that in mind.

Anywho, my 2 cents on 2xAA lights. They are too long to EDC (for me at least). The 1AA nitecore is awesome, and I love the multi levels and everything about it (would love to see the ramp in right direction from low/high put into the new ones too, are they?). With a clip it's a perfect EDC that gives you uber low which I thought I'd never use but I actually do when reading stuff at night.

But for a 2xAA light it's a bit too big to EDC. Only to carry when going in the woods, or what not. And if I'm going to carry something that isn't my EDC, I want it to be a big improvement (in power, or runtime) over my EDC, and will not care about ultra low light levels. For that reason, I would love the D20 if it were a bit of a different animal. Keep the PD design, but make it 2 mode only. Twisting/pushing further to go into high would be great, (much like the original PDs). 2 modes, turbo, and normal. Normal could be long runtime (no crazy 3 weeks needed here!) but bright enough for most everything like 60 lumens. Then turbo would be full tilt for when you need it. And since the light is not edc, and pretty long, might as well make the head pretty large. I wouldn't mind a 27-30mm reflector in a light like this. Give it some throw. Make it powerfull and 2 modes. Make it a ultility light not an EDC that has to cover all situations. Going into the woods you want a throwing light with decent run time, and 2xAA cree can do that without being as big as a C or D sized light. And if you make it 2 levels, you can make it constant current controled for more runtime. A torch like this in the same HA and PD design would rock. 

To me the long narrow 2xAA lights don't fit in one category fully. They need bigger heads to throw and put them in the utility/etc category, as they are bit too large for EDC, but don't throw much to put them in the larger light category. Can't we have a middle size between EDC and C/D sized lights in AA flavor? CR123a lights fill this section with some having large reflector heads, but not many 2xAA lights.

My 2 cents.


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## Federal LG (Nov 9, 2008)

selfbuilt said:


> ...Still need to do runtimes on the TK20 as well ... it will also be included in my eventual 2AA round-up.



Anxiously waiting for that! :wave:


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## the.Mtn.Man (Nov 10, 2008)

If I were to give my D20 a rating, I'd rate it a B. I love the ergonomics, I love the interface, I love the output range, but I'm not completely sold on the piston, which is ironic when you consider that this was the "killer feature" that pushed me towards this light in the first place.

As stated in the review, the "sticky piston" seems to be a fairly regular problem with this light. I cleaned off the stock lube and have been using Radio Shack Precision Lubricant on it which seems to work fairly well for a few weeks, then the piston starts getting stiffer and harder to work, so I have to disassemble the flashlight and do the maintenance thing again, which wouldn't be such a big deal if you didn't need small hand tools to do the job.

Does anybody have any suggestions, or should I just accept that I'll have to disassemble and lube the flashlight about once a month? You know, the Fenix LD20 is looking mighty attractive...


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## selfbuilt (Nov 10, 2008)

the.Mtn.Man said:


> As stated in the review, the "sticky piston" seems to be a fairly regular problem with this light. I cleaned off the stock lube and have been using Radio Shack Precision Lubricant on it which seems to work fairly well for a few weeks, then the piston starts getting stiffer and harder to work, so I have to disassemble the flashlight and do the maintenance thing again, which wouldn't be such a big deal if you didn't need small hand tools to do the job.


I'm finding my Radio Shack PTFE oil has also worn off now, leading to a metal-on-metal "clinking" sound when activating the piston (i.e. piston hitting the body tube). I've just re-lubed it with a small amount of Nyogel, which has solved the immediate problem - we'll see how long it lasts.

I'm also the finding the clip screws a little tricky to tighten fully - having to disassemble to access the piston o-ring is a bit of annoyance. We'll see if the nyogel lasts longer. I've updated the main post with these caveats.

Overall, the form factor remains impressive as a heavy-duty light based on regular batteries - as NiteCore intended. But I agree the Fenix remains a great choice as a general purpose light (especially for non-flashaholics)


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## csshih (Nov 10, 2008)

someone should try white lithium grease, as I asked before. that stuff won't wear off easily.


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## EngrPaul (Nov 10, 2008)

selfbuilt said:


> I'm also the finding the clip screws a little tricky to tighten fully


 
In another thread (Marketplace>Dealers>NitecoreClips) it was suggested 1.3 mm key fits these threads better than the supplied size.


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## TeamLosi (Nov 10, 2008)

This looks like a good choice for my first light. I dont' have the money to buy separate batteries (123's or 18650's) so i'm limited to a AA or AAA battery powered light.

Very nice review


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## the.Mtn.Man (Nov 11, 2008)

csshih said:


> someone should try white lithium grease, as I asked before. that stuff won't wear off easily.


I'd be willing to give it a shot. Now where to find white lithium grease... (and the quest for the perfect lubricant continues.)


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## Igor Porto (Nov 27, 2008)

Have you tried pure silicone oil to lubricate the piston o'ring? It should work very well, I use it all the time (not on a Nitecore, 'cause I don't have one yet), but on other o'rings that needs to be lubricated due to friction.


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## Tim B (Dec 25, 2008)

I have been thinking about getting this light but I have a question. On Nitecore's website as well as on 4seven's it says not to use lithium AA batteries. In fact it says this in large red letters on Nitecore's website. Does anyone know why? Will it damage the light? I read somewhere that lithium AA's put out a slightly higher voltage, about 1.7. Maybe this would mess with the processor. Any ideas? I have about 150 of these batteries stored up at home and it would be nice to be able to use them.


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## Burgess (Dec 26, 2008)

Hello Tim_B --


Welcome to CandlePowerForums !


:welcome:



To answer yer' question . . . .


(sigh)

You seem to have confused "Lithium Batteries" with

Lithium-Ion batteries. 


Nite-Core's website sez: " (not Li-ion batteries) "


Your Energizer L91 Lithium Primary Cells are fine.

:thumbsup:
_


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## Tim B (Dec 26, 2008)

Cool!


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## vestureofblood (Jan 23, 2009)

Hi,

Great thread. Thanks for the info


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## Helstar (Jan 24, 2009)

I got mine yesterday and I love it. I was also confused about the use of the Lithium batteries. So, I guess as long as they are just regular Lithium batteries they are fine, but if they are rechargeable that would make them Lith-ion and that would be bad correct? I will searching for the whole lithium information once I burn through the Rayovacs that I have. 
I will also post some outside usage pics when it gets a few degrees warmer. But I walk my little pocket dogs last night. I tried the light for the first time in a wooded area I am used to my Fenix P2d, anyway I was really nervous that the D20 was going to be like a mini mag compared to P2D. But wow. I clicked the button and I was a happy camper. I love this little light so far. Mainly due to the size. I will get some pics and a short review here in a few days.


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## adirondackdestroyer (Jan 24, 2009)

Helstar said:


> I got mine yesterday and I love it. I was also confused about the use of the Lithium batteries. So, I guess as long as they are just regular Lithium batteries they are fine, but if they are rechargeable that would make them Lith-ion and that would be bad correct? I will searching for the whole lithium information once I burn through the Rayovacs that I have.
> I will also post some outside usage pics when it gets a few degrees warmer. But I walk my little pocket dogs last night. I tried the light for the first time in a wooded area I am used to my Fenix P2d, anyway I was really nervous that the D20 was going to be like a mini mag compared to P2D. But wow. I clicked the button and I was a happy camper. I love this little light so far. Mainly due to the size. I will get some pics and a short review here in a few days.



Yes, you are correct. You can use Energizer Ultimate Lithium (L91) cells no problem, as they are only 1.7v each. You *CAN NOT* use recharge lithium cells in this light! They are 4.2v each and the light would go  in seconds if you used them. 
The output on this light should be the same (if not more) than the P2D that you have. This light is around 120-130 lumens out the front on high. 
I'm glad you enjoy it!


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## Brasso (Nov 2, 2009)

I just got my D20 R2 and to be honest, it doesn't look any brighter than my D10 and has more rings. At least to my eyes. The only thing it appears to do better is stay on longer. Still a nice light.


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## Kurtz (Nov 14, 2009)

Superb review. Thank you very much. It encouraged me to order one in the R2 version. Impatiently waiting for it to arrive next week (I hope so).


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