# [Review] MANKER E01 (Nichia 219, 1x AAA)



## _UPz (Mar 4, 2016)

*The manufacturer states Nichia 219C. Even though this spec might not be fully true, in the remainder of the review i am going to employ this spec'ed detail when referring to the emitter.
**


*
*MANKER E01*
*LED:* Nichia 219C
*Battery:* 1x AAA
*Modes:* 4 (Low-Med-High-Strobe)
*Switch:* Twisty
*Date:* March 2016

*INTRODUCTION:*
The Manker E01 is a simple and small flashlight from this new manufacturer, which it looks like we’re talking about a lot lately. Like any self-respecting brand, Manker now offers an “introductory” small and inexpensive flashlight, intended for everyday use or key ring. It is available in various colors. This flashlight is also marketed under the brand Astrolux, which can lead to some misunderstandings.



 




The product presentation is very similar to what we have seen in other flashlights from this manufacturer, with a small cardboard box in which we find the flashlight accompanied a spare o-ring and a small split-ring for the keychain. It also includes an user manual in two languages (Chinese-English).

*EXTERNAL FINISH:*
The exterior design of this flashlight is quite original, because of its rounded shapes and slight oversizing gives it a very own distinctive aspect.





It is machined in anodized aluminum with very nice matte finish, and has some very well-defined and easy to read engravings thanks to the high contrast obtained between the black background and white graphic. In addition to the brand and model, we have an indication with the correct polarity of the battery as well as another indication of the mode of use, all very basic.





The head of the flashlight has substantially larger diameter than the rest of it, and has a generous strip of knurling which greatly facilitates the grip of the head to make use of the twisty. The bezel is flat, with generously rounded edges.



 



The optics of this small Manker is composed by a OP reflector and Nichia 219 LED with neutral tint, properly centered, and all topped off with an AR coated glass lens.



 



The walls of the flashlight, especially in its connection between the head and body have a very generous thick. The driver disk is covered by a foam ring, which prevents the typical battery rattle when the flashlight is off, and in addition it also works as a mechanical protection system against wrongly installed battery (reverse polarity).



 



The threads are anodized, and arrive well bathed in lubricant from factory, as well as the o-ring. Twisty action is quite smooth.
The tube design is quite peculiar as it has “two volumes” but maintains a smooth design, with smooth curves at both ends. Tail design, also rounded, has a large hole to put the split ring. Machining surrounding it has some sharp angles. Of course, with a design so rounded the tailstand of this flashlight is stable at all.



 

 









Dimensions and very similar to the average in this type of flashlights weight.
*

USER INTERFACE:
*
The E01 has a fairly simple user interface, common with many other popular AAA flashlights:



*On and off:* This small Manker E01 turns on and off by screwing or unscrewing of the head. With fully screwed head flashlight turns on, with head slightly unscrewed flashlight turns off.



*Changing Modes:* To switch between modes we have to make a momentary off, to turn it on again in the successive 2 seconds. The order is ascending: L-> M-> H.



*Memory:* E01 has no memory mode, so after ~10 seconds from off it always starts on default Low mode.



*Hidden strobe mode:* To access the stroboscopic mode we must perform a sequence of six on / off (L-> M-> H-> L> M> H> Strobe).



 
_(All measurements are taken following the procedure ANSI NEMA FL1, taking as value the highest reading of between 30 and 120 seconds after activation. More details here.)
_
The three modes of this E01 are separated by great distances. In the user manual referred to as Low mode as Firefly, that with such sub-lumen mode like this that name would have been more appropriate. The Med mode, with 7LM is much more usable, and with maximum output mode we found a small discrepancy between measured by the sphere and specified by the manufacturer.


*PERFORMANCE:*


 

Performance in Hight mode with AAA Eneloop is quite discreet, with a smooth curve in which most of the time we move between 70 and 80LM.





Compared to other flashlights AAA, this E01 is not particularly outstanding nor maximum output nor for runtime. Click here for a view the image in higher resolution.


*EFFICIENCY:*
In this new feature for my reviews I will analyze the efficiency of each flashlight in a fairly simple way. Taking advantage of the data obtained in the previous runtime vs output test, we can make an estimate of the efficiency in lm·h, which will give us a value equivalent to the area that the line of each flashlight delineates between the X and Y axis of a graph as the one from previous section of this review. Given that all compared flashlights have been tested under the same conditions, using a battery of the same model and the same measuring instrument, we get the following result:



 
_(More details of how this calculation was made here.)_

We can see in this bar comparison chart how well each of the tested flashlights performs (in a given mode) in the task of converting the battery power into accumulated luminous flux. As expected, the flashlights with a lower regulated output mode, or with drastic stepdown such the E99Ti scores better *lm·h* results in such test as emitter efficiency is better in that lower output ranges.
In this particular case, the Manker E01 scores a fairly poor result, just above the old and outdated Tank007 E09.


*BEAM PROFILE:*
The Nichia 219 is undoubtedly the hottest point of this Manker, since it is difficult to see such emitter in a mass produced flashlight.
















The projection is very good with a medium-large hotspot well faded with spill with no artifacts or darker areas in the area surrounding the corona.
























Although the Nichia LED is slightly behind at maximum output or efficiency versus CREE alternatives, such the XP-G2, the Japanese manufacturer Nichia emitter offers a higher CRI (Color Rendering Index), so it is able to reproduce illuminated colors in a more reliable way or closer as sunlight would do.






_Camera WB: Daylight
_
*PERSONAL CONCLUSION:*
Although the flashlight has no special charm beyond the employ of a “gourmet” emitter, I must admit that for the price this is an excellent alternative for those looking for a neutral or high CRI flashlight simple, inexpensive and different from the rest in aesthetic design.


 


 
*Nextorch K10 · Olight i3S EOS · Tank007 E09 · Eagletac D25AAA Mini · Manker E01 · Ultratac K18 · Fenix LD01
*
*Negatives:* The E01 is a slightly over-sized flashlight, with a head that is somewhat larger in diameter and perhaps wasted space. The performance and efficiency of its High mode is poor compared with other similar single AAA flashlights. The spacing of the modes is a bit quirky, and the default activation mode may be too low for most situations.
*
Positives:* Undoubtedly the attractive price of this AAA flashlight is a good point, because it allows us to ponder its acquisition unceremoniously. The chosen LEDemitter is in my opinion another plus for Manker, because it offers us a great CRI, hard to find in mass produced flashlights and much less at this price.


_Manker E01 provided by manufacturer for review._​


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## jon_slider (Mar 4, 2016)

Thanks for the review and great photos

I would like to see side by side beamshots of the N219b (as in Astrolux) and N219c (as in Manker), like your color chart comparing the XPG2 and Nichia, much appreciated! 

Also please include PWM info in your review (a pic of the light being waved, or measured on a scope)


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## Fireclaw18 (Mar 4, 2016)

Looking at the pictures of the emitter in the E01 from the review in the top post on this page:

The emitter is definitely _*NOT*_ a Nichia 219C. The 219C has a very distinctive base (black, with white under the lens, and 4 white lobes at the corners). The E01 uses a different emitter, perhaps a 219B.

For comparison check Mountain Electronics listing for bare LEDs and look at the picture of the 219C. It's instantly obvious that what is in the E01 is not a 219C.


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## Tachead (Mar 4, 2016)

Yeah, this light has a 219B in it not C. You can easily tell from the pictures that it is a 219B.


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## jon_slider (Mar 4, 2016)

Fireclaw18 said:


> The emitter is definitely _*NOT*_ a Nichia 219C.


Thanks, I like the 219b a LOT! The Astrolux has nice High CRI imo, and I suspect the Manker is no different.. (I think the n219c tops out at 85CRI?)




for reference, here is the low CRI Olight i3s:


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## KeepingItLight (Mar 4, 2016)

Thanks, _UPz, for a fine review. I appreciate all the hard work you put into it.

I am intrigued by your efficiency rating. What are the starting and stopping times used for it? Do you start at time = 0, when the flashlight is first powered up? More interesting to me is the stopping time. Do you stop when output falls to 50% of max, 10% of max, or some other value? If so, how is max determined? Is it the output at time t = 0, or is it perhaps the highest output measured between 30 seconds and 2 minutes (i.e., the ANSI FL 1 output measurement)? 

For the way I use a flashlight, I would be more interested in efficiency up to the point when output reaches 50% of max, rather than the 10% point. I don't care much about output below 50%.

Thanks again.


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## jon_slider (Mar 4, 2016)

KeepingItLight said:


> I am intrigued by your efficiency rating.


I was curious too so I followed his link, and I speak spanish.. see his chart #5 describing how he calculates the area of the runtime and output curve.

Which means, a 4000k High CRI light/driver/battery combo with a Nichia, will have a lower "efficiency" score, than the same light/driver/battery combo with a Low CRI 6000k XPG2 

As you were asking about the testing method, I dont think hes using the factory specs, for example:
Maratac 138 lum for 70 min
i3s 80 lum for 35 min

If I read his link right, he uses his own runtime and lumen tests for the efficiency calcs, as he says:
"Los datos mediante los cuales calcularemos la eficiencia en LM*h son exactamente los mismos desde los cuales elaboro las gráficas de rendimiento."

by his calcs the Maratac scores 80 and the Olight 62 in efficiency, which calculates to the Maratac being 27% more efficient. The Maratac also uses brighter modes than the Olight, on all levels.. for example the claimed 138 lumens on high for the maratac is a full 73% brighter than the 80 lumen claim for the Olight.

so, if a Maratac is 27% more efficient, and 73% brighter, it would seem to me that the Maratac would end up having a 46% shorter runtime… I mean, somethings got to give.. no free lunch.. etc , or maybe the Maratac driver is really just sooo much more efficient than the Olight, that its simply a matter of a better driver.. not sure.. thoughts?


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## KeepingItLight (Mar 5, 2016)

Thanks, Jon. I think you are right about _UPz using his own data. 

As my many questions indicate, I am not too sure about much else. The English version above says that the area underneath the runtime curve is proportional (or equal) to the "efficiency." To find the area would mean calculating the integral between a selected starting time and stopping time. The starting time, for instance, is most likely when the flashlight is first turned on. The stopping time might be when the battery is completely exhausted. My questions try to nail down what these times are.

An efficiency rating that includes runtime after output has fallen to less than 50% of its maximum is not very interesting to me. I will likely be changing batteries when output reaches 50%, so anything after that can be disregarded. An efficiency rating that takes output down to zero would be the worst. 

The ANSI FL 1 standard stops runtime tests when output reaches 10% of max. For the way I use a flashlight, this does not yield useful information, either for runtime or efficiency.

I think the purpose of the statistic is measure driver efficiency. In this regard, stopping the test when output reaches zero would allow you to determine how much of the energy in a battery was converted into lumens. Hence, the term "efficiency." Unfortunately, that number is not interesting to me. I don't care very much about output after it falls to 50% of max.

A better way to measure driver efficiency is to do a simple calculation of power out (in watts) divided by power in. Averaging this value over the useful part of a run (i.e., down to 50% of max output) would yield a number that interests me.


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## eh4 (Mar 5, 2016)

Beautiful light. 
They should skip strobe and make a nice, reliable 4 mode light instead like L3 Illumination did. 
-Now that right there is a good light. 

Who in the first place, ever, Ever asked for a single AAA light that provides strobe as the last choice? Who did that? 

-No one who has ever been attacked whist wielding a mighty, mighty, single AAA light, that's who, lol.


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## Tachead (Mar 5, 2016)

eh4 said:


> Beautiful light.
> They should skip strobe and make a nice, reliable 4 mode light instead like L3 Illumination did.
> -Now that right there is a good light.
> 
> ...



People use the strobe for cycling and other activities to be more visible to cars during low light conditions.


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## _UPz (Mar 5, 2016)

Fireclaw18 said:


> Looking at the pictures of the emitter in the E01 from the review in the top post on this page:
> 
> The emitter is definitely _*NOT*_ a Nichia 219C. The 219C has a very distinctive base (black, with white under the lens, and 4 white lobes at the corners). The E01 uses a different emitter, perhaps a 219B.
> 
> For comparison check Mountain Electronics listing for bare LEDs and look at the picture of the 219C. It's instantly obvious that what is in the E01 is not a 219C.



Yes, You're right. There is a "mistake" in the user manual of the light and also in the website and I've fallen for it. Looks like the emitter is actually a 219B-V1 90CRI. Will check with manufacturer.
Sorry for the trouble.


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## _UPz (Mar 5, 2016)

Regarding the efficiency test, I'll try to explain it but please don't be hard on me as I am a very poor english speaker.

The calculation is the area a line delimites betwen axis X & Y of runtime vs output chart:





You can see cleary, in the Maratac and i3S detail, as the Maratac is much more efficient. If has higher output and longer runtime, using the exact same battery.

The data used for this calculation is the same used runtime vs output charts, and starts at t=0 and covers all the full log (not stopping at a given point, 10%, 50% etc) so the eff calculation is about the driver + emitter combo efficiency. I understand that a calculation of t = 0 to a 50% (from ansi value) will give tottally diferent numbers, specially in non-linear regulated flashlights, but won't make a big difference in flat regulated flashlights such the Maratac.

Thanks for reading and for your interest in this new review feature!


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## maukka (Mar 5, 2016)

Thanks for the lumen-hour measurements. I've also been meaning to do these. I wouldn't necessarily call it efficiency though, since lumen-hours can only be compared between lights that use the same battery. Better unit would be lm*hr/Wh or lm/w. For this the energy of the battery would have to be measured in watt-hours (very easy to do with an analyzing charger). The difficult part is what to use as the terminating voltage and you also have to consider lights with low voltage cutoff.

The concept is very easy to understand. For a 100 lm-hr light, it has an output equivalent of 100 lumens for 1 hour, or 200 lumens for 30 minutes and so on. As UPz explained in the spanish thread, this can be calculated as the area from the runtime/output chart.

Regarding the lumen-hour measurement to 50% or 10% I think the 10% figure would be the easiest, since the output after that is very minimal if measured in lumen-hours. Even though the light might stay on for 15 minutes after reaching 10% output, the total lumenhours of that last 15 minutes would be negligible compared to the total figure.


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## KeepingItLight (Mar 5, 2016)

Robin24k said:


> ​



In the foregoing charts, output for these Maglites on high is shown by the steeply declining red lines. Battery vampires may appreciate the long runtimes these sorts of flashlights offer. Most of the rest of us are not impressed. The ANSI FL 1 standard allows them to claim ridiculously long runtimes on high because FL 1 does not stop the clock until output falls to 10% of its maximum value. 

Because of this, most of us find the ANSI FL 1 standard to be practically useless when it comes to determining runtimes. In fact, the flashlight reviewer selfbuilt simply ignores it. His reviews measure runtime only to the 50% mark. 

For the same reason, I am skeptical of the efficiency rating discussed in this thread. It runs a flashlight down to zero output. This could allow flashlights with horrible runtime charts such as the ones above to obtain good efficiency ratings.

For flashlights with flat runtime curves the efficiency rating calculated in this thread may be useful. For flashlights with runtime curves such as those above, however, it is no more useful than the ANSI FL 1 runtime measurement. In those cases, such a number is worse than useless. It is downright deceptive. 

I understand that battery vampires may disagree. But the rest of us will usually be changing batteries long before we reach the 10% mark, and certainly before we reach the 0% mark required by this efficiency calculation.

Is there any way this calculation could be modified to take into account the way most of us use a flashlight? I, for one, would like to see a statistic tied to the 50% output level. Any output that could have been had by staying with the old batteries after that should be disregarded.

BTW: I like maukka's idea of calculating average lumens per watt. As he explains, that change eliminates any dependency on battery type. Such a calculation could also be stopped when output reaches the 50% level.


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## greenlight (Mar 5, 2016)

This this new flashlight might not be the most efficient flashlight in high mode, but how does it rank in medium and low mode?


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## _UPz (Mar 6, 2016)

maukka said:


> Thanks for the lumen-hour measurements. I've also been meaning to do these. I wouldn't necessarily call it efficiency though, since lumen-hours can only be compared between lights that use the same battery. Better unit would be lm*hr/Wh or lm/w. For this the energy of the battery would have to be measured in watt-hours (very easy to do with an analyzing charger). The difficult part is what to use as the terminating voltage and you also have to consider lights with low voltage cutoff.
> 
> The concept is very easy to understand. For a 100 lm-hr light, it has an output equivalent of 100 lumens for 1 hour, or 200 lumens for 30 minutes and so on. As UPz explained in the spanish thread, this can be calculated as the area from the runtime/output chart.
> 
> Regarding the lumen-hour measurement to 50% or 10% I think the 10% figure would be the easiest, since the output after that is very minimal if measured in lumen-hours. Even though the light might stay on for 15 minutes after reaching 10% output, the total lumenhours of that last 15 minutes would be negligible compared to the total figure.






KeepingItLight said:


> Is there any way this calculation could be modified to take into account the way most of us use a flashlight? I, for one, would like to see a statistic tied to the 50% output level. Any output that could have been had by staying with the old batteries after that should be disregarded.
> 
> BTW: I like maukka's idea of calculating average lumens per watt. As he explains, that change eliminates any dependency on battery type. Such a calculation could also be stopped when output reaches the 50% level.



Thanks!

Well, I will try to do a test-check, and calculate the lm·h to 50% and 10% with the same lights, so we can check the diferences.
Prior to deciding for this method (full log), I checked with my mma fliend differences with a 10% cut-off data, and differences were despreciables. 50% may have a big impact in non-linear regulated lights.
My aim is not finding an absolute measurement, but finding a comparable number so we can check easily which light in a typical runtime vs output chart is "delimiting" an higher area.
Thanks for the suggestions!


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## _UPz (Mar 6, 2016)

greenlight said:


> This this new flashlight might not be the most efficient flashlight in high mode, but how does it rank in medium and low mode?



Unfortunatelly I have no that much free time right now to do such long tests. Hopefully I find the time on future. Thanks for the suggestion!


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## jon_slider (Mar 6, 2016)

Im finding the efficiency chart very interesting. Are the Maratac and Worm the versions with PWM? (You can tell by looking at the reflector, a ring is present around the LED on the newer NoPWM models)


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## flashturtle (Mar 11, 2016)

Hard to ignore at the price point its at. I think i'll give this one a shot in my EDC bag.


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## _UPz (Mar 17, 2016)

jon_slider said:


> Im finding the efficiency chart very interesting. Are the Maratac and Worm the versions with PWM? (You can tell by looking at the reflector, a ring is present around the LED on the newer NoPWM models)
> https://lh3.googleusercontent.com/-...AAAAAAJ6A/-E_XtzIGcWc/s1136-Ic42/IMG_9913.JPG



Hello,
Sorry for late reply.
Maratac AAA Copper REV3 has PWN (old batch), Lumintop Worm Cu has NOT PWM (lastest batch).


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## _UPz (Mar 17, 2016)

Hello,

I've adjusted the efficiency chart with 50% and 10% values for my upcoming reviews.
Full log has been replaced by 10% as the calculation was almost the same. 50% calculations returns, as expected, higher values for flat regulated flashlights.

First review featuring the new double calculation can be seen here: http://www.candlepowerforums.com/vb...MecArmy-PT18-(3x-XP-G2-1x-18650-Rechargeable)
If I find spare time to re-calculate all the lights I've posted on this review, I'll update. If don't, you will see such calcs in upcoming AAA reviews.
Thanks!


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## jon_slider (Mar 17, 2016)

_UPz said:


> Maratac AAA Copper REV3 has PWN (old batch), Lumintop Worm Cu has NOT PWM (lastest batch).


Thanks! The PWM Maratac shows longer runtime, more lumens, and more efficiency than the NoPWM Worm

I suspect the new NoPWM Maratac would score lower in efficiency than the PWM version. If you ever get a chance to test a NoPWM Maratac, I will be curious to see if it matches the NoPWM Worm.

I note also that the Manker E01 is a NoPWM light, and its efficiency is similar to the NoPWM Worm.

which suggests that the lights with higher efficiency scores, use PWM.. Is that accurate?


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## markr6 (Apr 4, 2016)

I have one of these sitting in my mailbox! Can't wait to try it out. I'm a sucker for inexpensive Nichia lights.


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## markr6 (Apr 5, 2016)

markr6 said:


> I have one of these sitting in my mailbox! Can't wait to try it out. I'm a sucker for inexpensive Nichia lights.



Got it. Man, this baby is WARM! Makes my L11C 219B look like a CW. Not bad, but just not my preference. 4500-5000 is where I want to be.

Not a bad light. It was a $11 impulse buy, but I should have just paid up and got the D25AAA. Cycling thru that strobe is a big PITA.

Edit: after using this more, I'm really liking it...everything about it! This may actually turn me on to more warm lights. I just compared it to my Fenix E05...I had to try really hard not to just throw that one into the trash, because that's what it is, cool blue trash.


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## mikemalone (Apr 27, 2016)

The E01 in copper is beautiful.


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## Manker (May 24, 2016)

It's 219B


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## this_is_nascar (Mar 29, 2017)

Has the Manker E01 changed any since this review or is it still a light not worth having?


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## jon_slider (Mar 29, 2017)

this_is_nascar said:


> Has the Manker E01 changed any since this review or is it still a light not worth having?



I thought the one not worth having was the present Astrolux version
the Manker I thought were still good
the issues on the Astrolux include next mode memory (weird)
the Manker has no memory (good)

conclusion, buy the Manker, do not buy the Astrolux


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## this_is_nascar (Mar 29, 2017)

Ok, thx. What's a good source?


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## markr6 (Mar 30, 2017)

Too bad they're not on amazon anymore. Going Gear has them for a few $$ more.


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## RI Chevy (Mar 30, 2017)

Worth it to just get it from goinggear.com if you really like the light.


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## this_is_nascar (Mar 30, 2017)

Thx. Amazon was the 1st place I looked 😀.


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## this_is_nascar (Mar 30, 2017)

Just ordered one. Thanks again.


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## kaichu dento (Mar 30, 2017)

They're still available on the Bay too, purple, green, red and black when I looked just now.


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## sbslider (Apr 9, 2017)

I bought a purple one a month or two ago. It is a great bedstand light, I love the light beam color and the firefly mode. What I don't love is that the electronics are not attached well to the heat sink, and the heat sink was not anchored in to the bezel (right word?). I took mine apart today and applied some silicone to the electronics and heat sink to get it to stay together (hopefully). It has been a bit wonky of late and I think this will fix that problem. 

I got 200 hours out of mine on firefly mode using an eneloop. It was barely usable at the end of this time, but definitely still producing light. I believe I would get more using an alkaline, as they have more capacity. But I also believe the E01 is not regulated, so the light will be brighter (and draw more current) from an alkaline running at 1.5V than an eneloop running at 1.3V. Maybe another test in the works when I get my light back together . . .


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## this_is_nascar (Apr 9, 2017)

sbslider said:


> I bought a purple one a month or two ago. It is a great bedstand light, I love the light beam color and the firefly mode. What I don't love is that the electronics are not attached well to the heat sink, and the heat sink was not anchored in to the bezel (right word?). I took mine apart today and applied some silicone to the electronics and heat sink to get it to stay together (hopefully). It has been a bit wonky of late and I think this will fix that problem.
> 
> I got 200 hours out of mine on firefly mode using an eneloop. It was barely usable at the end of this time, but definitely still producing light. I believe I would get more using an alkaline, as they have more capacity. But I also believe the E01 is not regulated, so the light will be brighter (and draw more current) from an alkaline running at 1.5V than an eneloop running at 1.3V. Maybe another test in the works when I get my light back together . . .


I just finished metering my Manker E01 and will be posting the results in the next day or two. It was a test in Med mode, as my goal is to test all my multi level 1xAAA lights in medium to compare to my Fenix E01. I used Energizer Ultimate Lithium cells in all the tests as that's what I use in my EDC lights.


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## sbslider (Apr 18, 2017)

this_is_nascar said:


> I just finished metering my Manker E01 and will be posting the results in the next day or two. It was a test in Med mode, as my goal is to test all my multi level 1xAAA lights in medium to compare to my Fenix E01. I used Energizer Ultimate Lithium cells in all the tests as that's what I use in my EDC lights.


I assume you are talking about this graph:



this_is_nascar said:


> So, the sole purpose of this series of tests was to take all my 1xAAA lights with a similar output to my Fenix E01 and see if technology has advanced far enough to surpass the runtime vs brightness advantage that's always been in favor of the E01. As I've stated dozens of times over my time here on CPF, the three biggest advantages of the Fenix E01 over other lights of that period (for me) were 1) it's ability to fire on a nearly depleted cell, 2) the constant output runtime and 3) it's ability to take any abuse you can through at it.
> 
> I find the results interesting, but it should be noted, that the E01 used was an original, when they 1st came out. I thought I've read that Fenix has since upped the brightness and lessened the runtime or something along those lines.


 I found that data very useful, thank you for generating it and sharing. I took the time to characterize my Manker E01 in the only way I can, which is to measure the voltage and current into the driver with a calibrated power supply. I don't have a light meter, so I use the power supply to tell me if/how the light attempts to regulate. The data I gathered for medium mode for simulated battery voltage of 1.7V down to 1.01V was that the power into the driver is very constant. From this I conclude the light output is also constant. Two example data points are for 1.7V input, the current is .0.56A, so the total power is 0.095W; for 1.01V input, the current is 0.098A, so the total power input is 0.099W, or only 4% different than the 1.7V input. Somewhere below 1.01V the light likely comes out of regulation and the output falls of quickly as your graphs show. The driver puts out a tiny bit of light with 0.85V input, and is out when the input drops to 0.8V. 

What was more interesting was the behavior on Low and High mode. In low mode, the current into the driver roughly follows the voltage into the driver. That is, for 1.7V in, the current is .007A, so the total power input is 0.012W. For 1.01V input, the current is 0.003A, so the total power input is 0.003W. No regulation going on here, the light dims as the battery voltage decreases. 

High mode is even stranger. From 1.7V to 1.5V input, the light appears well regulated. But between 1.5 and 1.4V. the input current jumps by 30%. As the voltage continues to go down the current goes up for a bit, then at 1.2V start decreasing. It makes me think this light is well suited for a lithium iron battery on high, but not so much an alkaline or even Nimh rechargable.


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