# Ultratac K18 (XP-G2 S2, 1xAAA/10440, side switch) flashlight review: RUNTIMES+



## selfbuilt (May 5, 2016)

_*REVIEWER'S NOTE:* I am backed up with review samples again, so will only be providing abbreviated comments in this review. All the usual analyses and results are presented, however._















Ultratac is a relatively new maker on the scene. Here, I have their popular initial offering, the 1xAAA K18. Unusually for this class, it features a clicky switch in the head. I have the stainless steel version for review.

*Manufacturer Reported Specifications:* 
_Note: as always, these are only what the manufacturer reports. To see my actual testing results, scroll down the review._


LED: CREE XP-G2 Cool White
Output/Runtime AAA: Hi: 110 Lumens / 1h, Med: 25 Lumens / 5.7h, Lo: 3 Lumens, 45h
Output/Runtime 10440: Hi: 360 Lumens / 20min, Med: 80 Lumens / 1.5h, Lo: 5 Lumens, 15h
3 Light Levels, Plus Strobe
Beam Distance: 84m
Peak Intensity: 1764cd
Side Button Switch: Provide convenient one-handed operation. No need to twist the head for mode switch.
Convenient one-handed operation
Super Long Standby Time: Ultra-low standby current. 80% power 1 year later.
Compatible with A Variety of Batteries: 1.5V Alkaline AAA, 1.5V Lithium AAA, 1.2V Ni-MH AAA, 3.7V Li-Ion 10440.
Direct Thermal Patch (DTP) Copper MCPCB: Direct Thermal Path Copper MCPCB provides excellent heat dissipation to ensure the best light performance.
Reverse polarity protection
Compact size and light weight
Body Material: Aluminum, Stainless Steel, or Brass
Lens: AR coated lens, 99% light transmittance
Two-Way Clip provides More Carrying Options: UltraTac K18 comes with detachable two-way clip, the flashlight can be put in a purse, pocket, or simply fasten onto your cap.
Impact Resistance: 1.5m
Water Resistance: IPX-8, 2m
Weight: grams 14, oz 0.49
Length: Inches 3.0, mm 75
MSRP: ~$22-$30, depending on body material






















Again, my review sample is the Stainless Steel version.













From left to right: Eneloop Pro NiMH AAA; Lumintop Tool Ti; Ultratac K18; Lumintop Worm; Fenix LD02; Thrunite Ti3; L3 Illuminations L08. 

*Ultratac K18 Stainless Steel*: Weight: 29.5g, Length 76.0mm, Width 14.0mm (bezel)

*Fenix LD02 (with clip)*: Weight: 16.5g, Length: 76.9mm, Width (bezel): 14.4mm
*Fenix E99Ti*: Weight: 18.7g, Length: 66.1mm, Width (bezel): 14.1mm
*Foursevens Preon P1*: Weight 15.3g (with keychain clip), Length 75.6mm, Width 14.0mm (bezel)
*L3 Illumination L08*: Weight: 22.4g, Length: 77.8mm, Width (bezel): 17.0mm
*Lumintop Tool Ti*: Weight: 22.6g, Length 73.6mm, Width 14.4mm (bezel)
*Lumintop Tool AAA*: Weight: 15.3g, Length 82.6mm, Width 14.4mm (bezel)
*Lumintop Worm Stainless*: Weight: 27.3g, Length 72.0mm (battery installed, off), Width 14.1mm (bezel)
*Olight i3 (2013/14)*: Weight 12.3g, Length: 69.3mm, Width (bezel): 14.0mm
*Thrunite Ti3*: Weight: 11.5g, Length: 69.9mm, Width (bezel): 13.6mm
*Titanium Innovations Illuminati Aluminum*: Weight 13.9g (with keychain clip), Length 68.8mm, Width 14.0mm (bezel)


















The side switch has a standard feel for an electronic mode-changing switch, and is located under grippy a rubber cover (easy to find by touch alone).

Please see my video overview below for more information about the build.










*User Interface*

Press and hold the electronic switch for at least 0.5 secs to activate the light. 

Light comes on in its last memorized mode. Click the switch to advance through modes. Mode sequence is Lo > Med > Hi, in a repeating loop. Press and hold the switch for 0.5 secs to turn off the light. Memory for the last mode used is retained.

Double-click the switch from On to active strobe. Single click or press-hold to exit. There is no memory for strobe mode.

Double-click from Off to lock out the light (light will flash once). Double-click again to release the lock out (light with flash twice).

*Video*: 

For information on the light, including the build and user interface, please see my video overview:



For all my videos, I recommend you have annotations turned on. I commonly update the commentary with additional information or clarifications before publicly releasing the video.

As an aside, if you want to get an instant notification for every new review that I post, you can subscribe to my YouTube channel. The vids go public at the same time as the reviews here on CPF.  

*PWM/Strobe*

The K18 uses pulse width modulation (PWM) at its Lo and Med levels, at a consistent 3kHz frequency:

Hi





Med





Lo





This PWM is high enough to not be distracting in actual use, although I find it is still detectable at the lowest level (if you are sensitive to it). As usual, there is no PWM on the Hi level.

Strobe





Strobe is a fairly typical 10 Hz fast strobe.

*Stand-by:*

As on/off and mode switching is controlled by an electronic switch, there is going to be a standby drain.

On my DMM, the current fluctuates initially, but seems to settle down to around 0.14mA. For a 900mA Eneloop Pro, that would translate into just under 9 months before a battery would be fully drained.

It is likely that the electronic lock-out mode would lower this further, but I haven't tested it. The aluminum version should have a physical lock out as well, due to anodized screw threads (not possible on stainless steel)

*Beamshots:*

All lights are on 1xAAA Sanyo Eneloop NiMH, about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance is set for the Cool White emitters, to minimize tint differences. All beamshots taken immediately upon activation.














































*Testing Method:* 

All my output numbers are relative for my home-made light box setup, as described on my flashlightreviews.ca website. 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 any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

I have devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lightbox values to Lumens thread for more info. 

*Throw/Output Summary Chart:*

My summary tables are reported in a manner consistent with the ANSI FL-1 standard for flashlight testing. Please see http://www.flashlightreviews.ca/FL1.htm for a discussion, and a description of all the terms used in these tables. Effective July 2012, I have updated all my Peak Intensity/Beam Distance measures with a NIST-certified Extech EA31 lightmeter (orange highlights).






Here is how my lumen estimates compare to the Ultratac specs:






Impressive levels of output on 10440 – and good mode spacing overall, on all batteries.

*Output/Runtime Comparison:*





























See my wrap-up section for comments on the runtimes.

*Potential Issues*

The light uses PWM for its Lo/Med level, but at an unobtrusive high frequency of 3kHz.

There is a standby drain due to the electronic switch, which is reasonable at just under 9 months for an Eneloop Pro AAA. Locking out the light electronically should lower this drain and allow a battery to last longer. The stainless steel build tested here cannot be physically locked out, as anodizing is not possible. However, I expect the aluminum build would have this feature.

Tailstanding is not possible.

*Preliminary Observations*

The K18 is a quality built light, consistent with others I have reviewed in this 1xAAA class. The side-mounted electronic switch is certainly distinctive here – I haven't seen that before. oo:

Physically, this light seems comparable to many others in this class – although I only have the stainless steel version to compare. It is a decent build, with a good range of output levels. I particularly like the Lo to Hi mode sequence, and it does have mode memory.

The electronic side switch worked well in my testing, and is easy to access by touch alone (i.e., it protrudes sufficiently, with a grippy rubber cover). Press-hold for activation makes sense, and I appreciate the electronic lock-out option. I presume the aluminum version can be physically locked out at the head.

Output/runtime performance of the light is very good for this class, on all batteries - despite the use of high-frequency PWM on the Med/Lo levels. Rest assured, the PWM frequency is high enough (3kHz) that it is very hard to detect it visually – and will not be a concern in practice. 

I am actually quite impressed with how well it performed on standard alkaline and NiMH rechargeables. :thumbsup: Note the L92 lithium performance was not as impressive as some of the competition. But it is a nice touch that 10440 is officially supported in this light – with higher outputs. They have done a good job maintaining reasonable output modes for all battery types.

This is a nice light, with a good implementation of a novel switch position. If you are not a fan of twisy keychain lights, then this is certainly another clicky option. It is also capable of incredibly high output, with the officially supported 10440 option. No issues, the light performed very well in my testing. 

----

K18 provided by Ultratac for review.


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## Vothelo (May 5, 2016)

Great review as always! Quick question, is the double click from off lockout a new feature? My K18 aluminum that I've had for three months does not have that feature....and it's actually the one feature that I wish it had....when I saw it mentioned in your review I got all excited but no luck.


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## Wendee (May 5, 2016)

Thanks for another great review, selfbuilt! 
Your reviews are what led me to CPF. I can't count the number of times I've Google searched: "flashlight model" + review + selfbuilt. 
I certainly appreciate you taking time to do these reviews (as I'm sure everyone does). :thanks:
The K18 looks like a nice flashlight!


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## selfbuilt (May 5, 2016)

Vothelo said:


> Great review as always! Quick question, is the double click from off lockout a new feature? My K18 aluminum that I've had for three months does not have that feature....and it's actually the one feature that I wish it had....when I saw it mentioned in your review I got all excited but no luck.


Hmm, I guess it must be new then. I know this model has been around for a little while now - my sample was sent in February.



Wendee said:


> Your reviews are what led me to CPF. I can't count the number of times I've Google searched: "flashlight model" + review + selfbuilt.
> I certainly appreciate you taking time to do these reviews (as I'm sure everyone does). :thanks:


Thanks, always nice to hear.


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## mayo (May 5, 2016)

Had this one for a month now. Rocks on 10440. My new edc. Thanks for the review.


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## kreisl (May 5, 2016)

Thanks for the great review!!

UPz had reviewed the black K18, candlelamp too. It's become a popular item on the German forum. I removed the clip and the light has been on my keychain for months now. Still looks like new. I use a light-weight 10440 in it .. fantastic beam, non-greenish tint. Also super effective for curing mosquito bites on the skin.

Here is a tint comparison video where the K18SS is featured last:

https://www.youtube.com/watch?v=OKF1uYS4dGY

Don't mind the music though :sick2:


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## toylover (May 5, 2016)

kreisl said:


> ...Also super effective for curing mosquito bites on the skin.



Well, I never thought about that! My regular AAA lights don't produce enough heat for that. I presume you are using a 10440? What other single AAA lights can safely handle a 10440?


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## NCF8710 (May 6, 2016)

I also have the black anodized aluminum K18. I've had it for 7 weeks and use it with an IMR 10440 cell. No electronic lockout, but does lock out with a 1/4 turn of the head. It is my current key chain EDC light. I need to keep track of the charge level as the cell is unprotected.


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## Capolini (May 6, 2016)

Thanks for the review SB!

I have Four key chain lights[went on a little binge a few months ago!] I have the K18SS, K18 Blue Al., Olight i3E and i3S CU.

Yes,the Aluminum version of K18 has a physical lock out w/ just a slight twist of the head.

I chose the K18SS for my key chain light. The extra weight does not bother me. It is attached to my carabiner. I LOVE the fact that it takes 10440 L.Ion.This fits the bill w/ the high output it possesses for such a small torch,,,,,,right up my alley w/ my High output modded VINH lights!

I like the versatility w/ all the other batteries it takes. I am a MUCH bigger fan of a side switch than a Twisty! 

I am very satisfied w/ the light.


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## KeepingItLight (May 6, 2016)

Thanks for the review!

Does Ultratac say what happens when a Li-ion 10440 battery gets low?


Is there a low-voltage cutoff that turns off the flashlight completely? 
Is there a low-voltage warning that blinks the main beam or an LED? 
Is there neither? 
If the flashlight is accidentally activated, or is left on, is it possible to over-discharge a Li-ion 10440 battery?


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## Capolini (May 7, 2016)

^^^^

SB can verify this or tell me I am wrong!!!

I believe there is NEITHER. I did run time tests on max where the last 2 minutes[min 18 to 20] caught me by surprise and the voltage was below 2.0v iirc. The battery works fine after that test which was a few months ago.

It will certainly over discharge if left on when not aware of it. 

Simple solution...........slight twist of head for ALUMINUM versions and Double cl. to activate lockout for this, SS version. Double cl. to reactivate.


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## selfbuilt (May 8, 2016)

Capolini said:


> SB can verify this or tell me I am wrong!!!
> I believe there is NEITHER. I did run time tests on max where the last 2 minutes[min 18 to 20] caught me by surprise and the voltage was below 2.0v iirc.


Capolini is correct - there is no evidence of a low voltage cut-off, nor advance flashing. Once the output has dropped noticeably, you have probably already taken your 10440 to unsafe voltages. 

This is not uncommon in multi-power AAA lights that accept 10440. :shrug:


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## KeepingItLight (May 9, 2016)

Thanks, guys, for the info!

Knowing how a Li-ion flashlight handles over-discharge is an important piece of information for me. 

I do not know whether protected versions of the 10440 battery are available, but if so, this flashlight sounds like a good candidate for one.


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## GordoJones88 (May 9, 2016)

Shiny!


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## Gryffin (May 9, 2016)

selfbuilt said:


> Hmm, I guess it must be new then. I know this model has been around for a little while now - my sample was sent in February.



My guess is, they added the electronic lock-out to the stainless model because it can't do a mechanical lockout. Still, like others here, I'd appreciate it on the aluminum model as well.


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## PB Wilson (May 26, 2016)

I've had my stainless steel K18 for about a month now and like it quite a lot. It's a bit heavier than my wife's aluminum one, but I had read/heard on youtube that the aluminum ones might not have enough length to swallow a protected 10440.

I've been using TrustFire 10440 cells and like the extra brightness they provide (even if it's for a short amount of time). These are protected cells and if they weren't, I'd probably be sticking with AAA cells exclusively. 

I like the size, the general feel of sturdiness, brightness and the side button. The first one I ordered had a tear in the rubber of the switch, but GoingGear straightened it out in no time with a replacement. I hope the rubber switch cover stands up to the test of time...


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## Capolini (May 26, 2016)

PB Wilson said:


> I've had my stainless steel K18 for about a month now and like it quite a lot. It's a bit heavier than my wife's aluminum one, but I had read/heard on youtube that the aluminum ones might not have enough length to swallow a protected 10440.
> 
> I've been using TrustFire 10440 cells and like the extra brightness they provide (even if it's for a short amount of time). These are protected cells and if they weren't, I'd probably be sticking with AAA cells exclusively.
> 
> I like the size, the general feel of sturdiness, brightness and the side button. The first one I ordered had a tear in the rubber of the switch, but GoingGear straightened it out in no time with a replacement. I hope the rubber switch cover stands up to the test of time...




I have the Aluminum and SS version. EFEST IMR 10440 fit fine in both. 

I would go w/ EFEST,MUCH better and safer battery than Trustfire,,,,,sorry I would not get caught dead w/ Ultrafire/Trustfire ECT... "Fire"!!!


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## PB Wilson (May 27, 2016)

Point well taken regarding the TrustFire. 

The name seems like they're trying a bit too hard but still reminding you what might happen if you're careless...


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## Capolini (May 27, 2016)

PB Wilson said:


> Point well taken regarding the TrustFire.
> 
> The name seems like they're trying a bit too hard but still reminding you what might happen if you're careless...




HKJ is well known and respected for his work/reviews of batteries/chargers. Check his review on an ULTRAFIRE battery,,Trustfires are in the same league!!! LINK BELOW:

http://lygte-info.dk/info/batteryDisassemblyUltraFire UK.html


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## LarcKen (May 29, 2016)

Capolini said:


> HKJ is well known and respected for his work/reviews of batteries/chargers. Check his review on an ULTRAFIRE battery,,Trustfires are in the same league!!! LINK BELOW:
> 
> http://lygte-info.dk/info/batteryDisassemblyUltraFire UK.html



Hi there, nice to meet you guys. I have a different opinion on Trustfire, they are definitely not in the same league as Ultrafire. Have you actually owned one? In my case, i have five Trustfire 18650 3000mah, tested the capacity and it's all acceptable at 2800-2900 mah. They work just fine on my pure 3000+ lumens flashlight with decent runtimes. The protection circuit seems to work also. 
To further prove my point, just try to randomly order an Ultrafire and Trustfire. With Ultrafire, you'll get 99% crap battery with 500mah max capacity on 18650, or 150mah on 16340. On the contrary all my Trustfire purchase have been very pleasing for the price.


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## Capolini (May 31, 2016)

LarcKen said:


> Hi there, nice to meet you guys. I have a different opinion on Trustfire, they are definitely not in the same league as Ultrafire. Have you actually owned one? In my case, i have five Trustfire 18650 3000mah, tested the capacity and it's all acceptable at 2800-2900 mah. They work just fine on my pure 3000+ lumens flashlight with decent runtimes. The protection circuit seems to work also.
> To further prove my point, just try to randomly order an Ultrafire and Trustfire. With Ultrafire, you'll get 99% crap battery with 500mah max capacity on 18650, or 150mah on 16340. On the contrary all my Trustfire purchase have been very pleasing for the price.




Yes I have tried them in the beginning of my hobby when I did not know any better!

I choose to use QUALITY brand names like PANASONIC, LG,SONY,SAMSUNG AND SANYO.

You will find that most people will choose the safer/better quality/realistic mAh batteries that I listed.

:welcome:


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## Flashh (Sep 8, 2016)

I purchased one of these off eBay. After limited use on my wife's keychain the button is stuck and it doesn't work anymore. We would have used it about 5 times in the 2 months we have had it. No refund just disappointed.
Letting everybody know that quality can be missing. :thumbsdow


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## kreisl (Oct 25, 2020)

selfbuilt said:


> There is a standby drain due to the electronic switch, which is reasonable at just under 9 months for an Eneloop Pro AAA. Locking out the light electronically should lower this drain and allow a battery to last longer. The stainless steel build tested here cannot be physically locked out, as anodizing is not possible. However, I expect the aluminum build would have this feature.


As we are hearing, the _alu _build can be physically locked out yes.

Unlike drivers of _other _1×AAA SS (or Titanium) flashlights, on the K18 SS the driver disc is *not *electrically insulated against the SS head. :huh:Actually this electrical situation is due to the installed/screwed *brass retainer crown* which is to hold the driver disc in place AND serve as physical reverse polarity protection (RPP) at the same time.

Today i wanna talk about the RPP (and next time i'll talk about the standby current drain).

The stepped brass retainer ring ("crown", "spacer") has an inner diameter of Ø10.00mm, easy to measure. In theory, it spaces AAA battery bottoms ~1.0mm away from contacting the metal(+)contact of the driver disc; on the 2019 SS model the clearance is more like ~0.5mm because it has a raised metal(+)contact. There are two potential issues with this idea/design of physical RPP, *depending *on the AAA/10440 battery model you insert reversely.

case1) If the battery is thicker/wider than Ø10.00mm AND the battery bottom is bare, i.e. not partially covered by heat shrink wrap/tubing/sleeve material or alike, then the reversely inserted battery gets short-circuited, as soon as the SS body touches the SS head. Shorting a fully charged battery can be hazardous, bye-bye battery A commercial example would be your standard Eneloop AAA battery, it has a bare bottom. Another commercial example would be blue unprotected UltraFire TR10440 (600mAh 3.6V). 

case2) If the battery diameter is less than Ø10.00mm, say Ø9.8mm, then the battery bottom will(!) contact some part of the driver disc and eventually, depending on the battery model and the K18 SS version, electrically contact the metal(+)contact in the center of the driver disc, thus leading to an established reverse battery connection, bye-bye driver  A commercial example would be (fake?) Panasonic AAA Alkaline, which comes in at Ø9.65mm om*g. So yes —_and feel free to check with all AAA/10440-sized batteries in your household_— batteries slimmer than Ø10.00mm do exist and that is a reason of concern.

My point being, only because the K18 SS is advertised as having "Reverse polarity protection", in general you should NOT just go ahead and mindlessly insert _any _AAA/10440 battery reversely for fooling around or testing/trying to understand the RPP. The good news is that some/many batteries, for example the originally included noname blue unprotected 10440 battery, has a thickness of Ø10.2mm AND not a bare bottom, so neither case1 nor case2 comes into effect yay! :naughty:

The "unnecessary" mod. There's nothing much we can do to mitigate case1, hopefully you realize fast enough when you have reverse-installed a blue UF10440 or Eneloop AAA; at least you didn't wreck the driver haha. But we can eliminate case2 by installing a plastic spacer/donut/ring, as we did for the LD01 SS before:






Here a modding advantage, the conductive brass retainer ring serves as centering aid for our purpose nice thanks and we can :thumbsup: friction *press-fit* the plastic spacer without the need of glues, adhesives, or tapes, hooray:





Shortcoming:
Ultratac's idea of physical RPP is a ~1.0mm (~0.5mm) spacing brass ring and maybe they should have tested an inner diameter of Ø8.50mm to mitigate case2. Ch*nese batteries with w*ld (+)pole assemblies exist, see photo above, so making a spacer out of brass isn't the best idea to start with, because a reversely installed battery could get easily shorted. The advantage of brass is that it is permanent material/installation unlike a taped foam donut lol, and that we can use it for press-fitting a plastic spacer (to mitigate case2). In the end imho it is better to have this brass solution (which can be enhanced with the shown plastic mod) than not to have any physical RPP. Just keep in mind that the original K18 SS RRP is not watertight (see case2) and that case1 is still a potential hazard. By comparison, my modded LD01 SS has no potential issues with case1 or case2 but it has a realistic other potential issue, namely losing the plastic donut spacer because of failing (weak/strong) adhesive! On the K18 SS, you will never lose the press-fitted plastic donut spacer and you will never lose the brass ring, because they are "perma-installed". Maybe that was the main reason why Ultratac decided for a brass solution instead of a foam donut solution. However, imho they should have tried brass rings with 8.00, 8.50, 9.00, and 9.50mm diameter, because obviously 10.00mm wasn't _the _optimal choice.


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## kreisl (Oct 25, 2020)

selfbuilt said:


> *Stand-by:*
> 
> As on/off and mode switching is controlled by an electronic switch, there is going to be a standby drain.
> 
> ...


I have tested it: the standby current drain is the same, no matter if the light is simply off (_ON » longpress button » OFF_) or electronically locked out (_OFF » doublepress button » electronically secured OFF_). The drain depends on battery *chemistry *(i.e. voltage level) and *charge *level (i.e. voltage). That is, quoting random stuff like "_standby drain of 6.7mA (0.0067A) when light is off or locket out_", "_wow the new head (2016) has 0.017mA standby current, nice!_", and "_my mint K18-2019 has 0.031mA standby drain (0.000031A), which is very good_" isn't helpful since the battery chemistry is unclear and the charge level is unclear from those statements.

I have at least four K18 SS retail units in my collection incl. a ForoL special edition. Imho it's still "the best" 10440-capable 1xAAA *actual keychain carry* flashlight, and I am meaning the K18 SS version in particular, not the various K18 _alu _versions. To be fair, only very few 1xAAA flashlights exist which officially support 10440, so the competition is very sparse anyway. It was a shame that one of my early units "broke" after 3 years, 6.7mA was absolutely inacceptable, so i retired that unit; moreover, the black rubber button was consumed yumm. On my current K18 SS (has red driver board) the black rubber button is starting to get consumed too; that's why later K18's were released with metal buttons. Good to know that the black driver board was built to last, and its standby current is pretty low too; I just hope that i will never have to put my nice SS 2019-unit to use, to me it's a collection piece which i want to keep in mint condition.

Here my helpful reference table of standby current drains:


all values in [mA]10440 (*4.20V*)10440 (*3.27V*)Eneloop AAA (*1.50V*)Eneloop AAA (*1.28V*)Eneloop AAA (*1.05V*)notesK18 SS (2016) unit#10.0160.0240.1290.25233*red *driverK18 SS (2016) unit#20.0170.0280.1380.27133ForoL edition, *red *driverK18 SS (2016) unit#36.7 
(0.017 wth)n/a 
(0.037 wth)53
(0.185 wth)40/45
(0.700 wth)30defective *red *driverK18 SS (2019)0.0310.0400.2000.37433*black *driver

Conclusion: 
The standby current drain is nicely low (_and you should compare your own measurements with the above table, I am not sure where selfbuilt's quoted measurement falls into :shrug: _) and nothing of concern, especially with 10440 chemistry. If you measure a higher standby current on a production unit with a red driver disc, it could be an indication of a failing capacitor (repair is possible: the head screws apart right above the knurled section/clever invisible seam, no loctite was used during assembly). Production units with a black driver disc should not develop this electronic component failure because the company had improved the electronics build with that release. Too bad for latecomers, the *K18 SS 2019* does not seem to be in production #thankswuhan anymore (the _alu _version might still be tho). Note that on an overdischarged Eneloop AAA the circuit falls out of regulation, the current drain steps up to a higher rate level , sucking every last bit of juice from your NiMH battery. So you better run a well-charged Eneloop AAA in the light and not let it discharge too much. Even better, just use a 10440 instead!

EDIT: loool :candle: unit#3 was the retired unit because it had developed high standby drain. earlier today i had measured 53mA and 40mA on Eneloop, i.e. very high values signalling an electronic defect. I took current measurements for the 10440 (3.27V) _column _last. when i got to unit#3, the drain was 0.037mA only, surprisingly. so i took re-measurements for the _row _and got 0.017mA, 0.185mA, and 0.700mA altering with 45mA, funny! looks like unit#3 has an electronic hiccup and is "now okay again", temporarily. lol. because of that funny history, unfortunately i can't trust unit#3 to become a reliable daily driver again, therefore it's correct to leave that unit retired. If i ever needed spare parts/repair parts for unit#1, i could disassemble unit#3 for that purpose. failing red drivers were a topic 2 years ago, so i better be prepared. if my unit#1 becomes unreliable/defective, i'll update this thread with a report and photos.


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