Friday, February 11, 2011

Klarus Mi X5 AAAA Review


Klarus has recently released what they claim to be the smallest and brightest AAAA light in the world; the klarus Mi X5.


    * Emitter: Cree XP-E R2 LED with a lifespan of 50,000 hours
    * Four outputs:
          o 25 lumens(2.2 hours)
          o 2 lumens(26 hours)
          o 76lumens(40 minutes)
          o Strobe (76 lumens, 1.2 hrs)
    * Battery: Single AAAA (Alkaline, Ni-MH, Lithium)
    * Switch: Twist switch, Adjust output by rotating the flashlight head
    * Lens: Toughened ultra-clear glass
    * Material:Stainless steel
    * Dimensions:65.6mm (Length) x 9.2mm (Body) x 10.3mm(Head)
    * Net weight: 11g (Excluding battery)
    * Waterproof to IPX-8 standard
    * Digitally regulated output - maintains constant brightness, no PWM
    * Reverse polarity protection
The choice of using AAAA batteries is an interesting one, it is not a common battery format, but it does allow the light to be shorter and slimmer. There are very few lights around that actually use AAAA batteries.  The majority of the lights that do use AAAAs are multi-cell or use low-power LEDs.  From a quick google search, the only other single cell AAAA light I could find was the aunoc AAAA, which uses a low-power 5mm LED.  As far as I can tell, the klarus MiX5 does seem to be the smallest and brightest AAAA light on the market.


On receiving this light, I do have to say I was impressed by how small and thin this light actually is.  It has the 'baseball bat' styling found in the 4sevens preon 1; a thicker head that tapers into a thinner body.  This flashlight is significantly thinner than the AAA flashlights out there, with the body measuring 9.2mm and the head 10.3mm in diameter.  It measures 65.6mm in length which is shorter than most AAA lights, barring the DQG tiny which measures ~60mm in length.

Preon 1, Fenix L0D, Klarus Mi X5, Tiny DQG AAA, Modamag Drake, AAA eneloop battery, AAAA battery
Preon 1 (with tailcap), Fenix L0D, Klarus Mi X5, Tiny DQG AAA, Modamag Drake, AAA eneloop battery

The klarus mi x5 feels well made, solid in construction.  It is made from stainless steel, which does add to the weight when comparing it to aluminium.  However, as this light is already so small, the difference in weight between aluminium and stainless steel would not be very noticeable.

The surface texture of this light is a lightly brushed smooth stainless steel, there is no knurling present.  Some texture is provided by engraving of the brand name and serial number.  I feel the addition of knurling at the head, would make it easier to twist the light on-off.

The split-ring attachment on the klarus mi x5 is very solid, there would be minimal worries about this attachment being a weak point and breaking.  Unfortunately the design of the attachment does add a few more millimeters to the total length of the flashlight.  It also forgoes tail-standing abilities.

Solid lanyard attachment

One possible concern I have with this flashlight is the lack of a spring in the tail-end.  Such lights have a reputation of being 'battery crushers'.  However, as the klarus would most likely run on disposable AAAA batteries, there is less concern if the battery is 'crushed'.  The reverse polarity protection appears to be a piece of foam/rubber in the head of the light.  This foam should also help reduce battery crushing.

Included with the flashlight are six o-rings and one split ring.  Some people have reported having issues with the o-rings shredding.  My sample does not seem to have these problems, but I am not surprised to hear it occurring.  The o-rings included are very small and need to be stretched significantly to allow it to fit.  I would imagine as an o-ring gets stretched, the rubber becomes more stressed, resulting in a higher likelihood of fraying or breaking.

The o-ring is on the left.  You can see how small it is compared to the head.


The klarus mi x5 has 4 modes; medium, low, high and strobe.  To change between modes you need to quickly twist the light off-on until the desired mode is reached.  If you leave the light off for more than ~1 second, it will restart on medium mode.

There are pros and cons of having a M-L-H interface (vs L-M-H).  I don't mind the mode sequence in the klarus mi x5.  I find the low setting is fairly dim, and it is not bright enough for certain applications.  Medium would be my most commonly used mode, so it's handy having it at the start of the sequence.  

Some people prefer their lights to start on low, as they feel it is less likely to ruin their night-adapted vision.  Also medium can be too bright and distraction in some situations (e.g. looking for something you've dropped in the cinemas).  YMMV.  Some people don't like strobe or beacon modes, in this case the strobe is tucked away at the end of the sequence... I don't feel it is a huge problem having it there.

This light has current controlled regulation, there is no PWM... a big plus for me!  I am quite sensitive to PWM and find noticeable PWM can be distracting. 

I am a little dubious about the run-times that Klarus has advertised with Mi X5.  I ran a brand new energizer AAAA battery on the high mode.  Initially the output is quite bright, I checked again at 13 minutes and the light was less bright, maybe a little brighter than its medium mode.  By ~20 minutes the light was very dim, the output was unusable.  If you let the battery rest, the battery voltage will recover and it will run on high again, but for a shorter period than last.  The klarus will NOT offer 40 minutes of continual brightness on high, perhaps its will give you 40minutes in total if you use it sporadically.  I haven't tested the run times on the other modes, but I am dubious whether it is able to give continuous output at the manufacturer reported run times.

I don't have any equipment to test output and regulation, but to my eyes; after an initial drop in brightness, the medium and low modes do seem to maintain a consistent output, until the end when the battery starts to fail.  High does seem to tax the AAAA alkaline battery, the output does not appear as well regulated.  Hopefully, someone with a lightbox and measuring equipment can provide more empirical data.

Update:  Current draw from a fresh battery is ~170ma on medium, ~30ma on low, ~860ma on high


My sample of this light has a creamy white tint.  When looking at the beam from a further distance, my eyes detect a hint of green to it.  I'm not sure what tint bin it is.  It is not the usual WC 'cool-white' bin, I'm guessing it could be a WH or WG tint bin.

Due to it's smaller reflector the klarus mi x5 it has a fairly floody beam.  This may have been why Klarus has opted to used a XPE-R2 LED, instead of a XPG LED.  While XPG offers more efficient LEDs, the larger die tends to create a wider hot spot and beam.  In this flashlight a XPG would arguably be too floody.

Beamshots @ ISO 1600, F2.8, 1/8 shutter speed

Klarus Mi X5 AAA - medium mode
Klarus Mi X5 AAA - low mode

Klarus Mi X5 AAA - high mode


One of the initial things holding me back from buying this light was the cost.  In the end, I still bought one for novelty sake.  I like small lights, and I found the AAAA format an interesting one to have in my budding collection.  The klarus mi x5 can be bought from for $69 (not including shipping), which does seem pretty expensive for such a small light.

In discussions with Klarus, they claim the reason for this higher price, is that it is harder assemble and has a higher scrap rate.  The first batch is hand assembled by their chief designer, and as the light is so small, there is higher defect rate when inserting the circuit board into the body.

I feel one of the major limitations of this flashlight is the available AAAA battery chemistries.  The only AAAA battery that seems to fit this light are alkaline AAAA.  Alkaline batteries have a bad reputation of leaking, especially in high drain applications (such as power-LED flashlights). Alkalines are also prone to voltage sag, meaning the battery tends to drop in voltage as it is being used.  This means the alkaline battery can having trouble delivering enough power to the LED, when using it on brighter modes for longer periods.   However if you are only using the flashlight on your keychain for short periods of time, this voltage sag is less of a problem.

There are no primary lithium AAAAs available.  This is a shame, as they have a longer shelf-life, are less prone to leaking and have less voltage sag, than alkaline batteries.

There are actually AAAA nimh batteries with capacity of ~300mah (not very high considering a AAA can offer 900-1000mah).  They are difficult to find, however I did locate a source and bought a few to test out.  Much to my disappointment, I discovered they are a little too wide and do not fit into this light.
6xAAAA disassembled from a 9V battery

AAAA is not a common format and may be a little harder to find.  They can be bought cheaper online, however they are still more expensive than their AA or AAA counterparts.  If you are looking for a cheaper source of AAAAs, some 9v batteries can be taken apart to give you 6xAAAA batteries.  Just do a google search on how to do it.  Do note, if you are harvesting the AAAA from a 9v battery, the nipple is actually the negative end of the light and the flat surface is the positive end.  For these harvested batteries to work, you need to create contact in the positive end of the light.   Some aluminium foil or a very small magnet, will do the trick.  If you are going to use these harvested batteries, make sure you don't get your positive and negative ends mixed up.  By placing the aluminium foil/magnet in the head, you are bypassing the reverse polarity protection and you may damage your light if you put it in the wrong way.


If you find the AAA flashlight format is a little too large for your keychain, this may be the light for you.  Due to the small sized battery, it will have reduced runtimes, but it still offers you 4 current regulated modes with a respectable max of 76 lumens.  There are some other lights that also offer power-LEDs in a smaller than AAA format.  However these other lights usually need rechargeable batteries (e.g. 10180 li-ion, 10280 li-ion, 2/3AAA nimh).  The klarus mi x5 is a good alternative if you do not want to deal with the hassles of rechargeables.


  1. Update: Current draw from a fresh battery is ~170ma on medium, ~30ma on low, ~860ma on high

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  3. AAAA were very common in the 1980's. They were still widely available in the 1990's for doctos little lights that checked the ears & tongues.
    There is a Li-Ion 3.6v battery made, with a typical capacity of 170mAh. So if it was a Ni-MH, that would equate to:
    3 x 170mAh = 510mAH @ 1.2v ;-)
    Here is a link to a company that makes them:

    I could not find any other company at the moment, but every once in a while, they do pop up either on eBay or AliBaba/ AliExpress.
    Now since you did mention that it also works with Lithium batteries, it would be good to know how that would work / perform.