Jetbeam KO-01 Review

Hello. This is my first ever flashlight review, so it may be missing some information, or not all aspects properly reviewed, so feel free to ask and correct!

I will start with link to official website, so you can read the specs, and quick conclusion from myself.

http://www.jetbeamlight.com/ShowProducts.asp?ID=79

I bought it on Gearbest: http://www.gearbest.com/led-flashlights/pp_364378.html and paid $35. Now it is available for $26! I feel a bit ashamed

Pros:

Excellent build quality
Medium to wide flood beam
Switch located on side
Ability to charge battery in flashlight, using standard MicroUSB cable

Cons (subjective):

It is hard to differentiate on/off switch from charging port cap via tactile feeling
On/off/mode changing sequence is a bit slow
Battery rattles a bit (but no issue with contacts)
Gets damn hot in turbo mode quickly


How we "met":


I saw ad for this flashlight on the top of this forum, and decided to buy it due to numerous reasons. First of all, I've liked its simple, sleek design. I don't like these aggressively finned and too techy looking flashlights. 2nd​, I've liked that it has button on side, not on the rear cap, as most modern flashlights do, I really don't enjoy the real cap flashlights, so this one was pleasant exception from the crowd. Third, the battery can be recharged within the flashlight, saving time for unscrewing the cap each time, and avoiding need to have standalone charger. 4th – This flashlight has no clip included (but you can get one if needed), which I don't generally use, and usually remove as I unbox the flashlight. Additional plus is that clip is snap-on mounted, so if you don't use it, you will not see ugly holes from the missing screws. Another subjective plus – there are no "zoom" slides or any mechanical parts that can move, or need to be moved, while operating the flashlight.


How I'm going to use it:


While being an electronics engineer, I'm not kind of too techie guy – my "EDC Flashlight" is one, that is built in my cell phone and I don't feel any need for more advanced one. I'm also hobby photographer, and recently started to enjoy taking photos in abandoned buildings, shelters, etc. (Sort of "post apocalyptic" settings) So having a good flashlight is a must. I have some cheap "Ultrafire" flashlights and headlights, but their light quality, and especially, light amount, is quite low, so I definitely needed something more powerful. So this flashlight will be used during exploring various areas, basically to highlight area where I'm going to step in, so I don't needed needle-like beam, I wanted something with wider beam.


Packaging and what is included:

The flashlight comes in carton box, nothing heavy, crush-proof or nicely decorated. It does not have see-thru windows, fancy print, scratch-it security codes and so on. Only simple packaging with basic information about the flashlight, written in Chenglish and Chinese. Inside you will find a transparent plastic blister, paperwork (manual and warranty card), 1 foot MicroUSB cable, and set of spare o-rings and spare on-off switch cap.







Mechanical construction:

Workmanship is excellent, there are no visible flaws in manufacturing or paint job, everything is done at top notch level. Flash light is well balanced, and pleasure to hold in hand The body of flashlight is dark brown, with matte paint job. Reflector has smooth surface, and front glass (real glass, not plastic) has anti-reflective coating. Micro USB port has black rubber seal, and power button is made from greyish rubber. There's blue led inside the power button, which is on when flashlight is charging, and blinks, when battery is exhausted. Led is not too bright, so it won't disturb you during night time charging, but same time, it is bright enough, to spot it when it will start blinking, showing the low charge of battery. Tail cap unscrews easily. Threads are lubricated and additional o-ring seal is present. The "-" contact is spring-loaded and appears to be either gold, or titanium nitride coated. Positive pin is also spring-loaded. The flashlight accepts both button top and flat top batteries, also it accepts protected 18650 cells without any issues. Only minor issue is, that battery is a bit loose in flashlight, and makes bad sounds when moved around. Even double wrapped batteries have this issue. Couple layers of scotch tape fixes this issue, which isn't a big deal at all, but still...

























On the last picture, you can see size comparison with "Ultrafire" 18650 flashlight, and CR123A based "MXDL" flashlight.

Charging:

As already mentioned, battery in this flashlight can be charged internally, via built-in charger, using Micro USB port. The charging process starts with 0.8 amp current, which slowly goes down, as battery being topped. It will need about 3 hours to charge fully drained 2000mAh battery. This is definitely not fast, and with 3400mAh cell it might take up to 5-6 hours, so if you need faster turnaround, you might charge your battery in standalone, fast charger. During the charging process, flashlight gets moderately warm – maybe just 3-4C above the room temperature.

Operation:

To turn flashlight on or off, you need to long press the button. Flashlight has 4 modes – Turbo, High, Middle, Low, which can be changed in sequence with short click of the button. Flashlight slowly fades from mode to mode. When in "Turbo" mode, double click activates strobe. Flashlight remembers last used mode, when turned off. It even remembers the strobe mode, while manual says it does not.

Measurements – thermal:

Since this flashlight packs XP-L led and outputs up to 1080 lumens, thermal test is quite necessary. It was conducted in the following manner: Freshly charged battery was cooled to room temperature, and inserted into flashlight, also at room temperature. Then flashlight was set to various power levels and temperature measured using Flir E8 thermal camera. Flashlight was put horizontally on two wooden legs. After each measurement at different power levels, flashlight was allowed to cool down to the room temperature, before doing the next test. Temperature readings were constantly monitored, and test stopped and time recorded, when flashlight handle reached 37C (the temperature which is still comfortable to hold). Ambient temperature was 23C at the moment of testing. Results are summarized in the table below:




Measurements - Optoelectrical:

This flashlight uses PWM, to change brightness. PWM frequency is 18.2Khz, so it is not noticeable by eye at any power level. In "turbo" mode, PWM is switched off. Below you can see the PWM measurement (the descending slope is caused by my old selenium sensor, which can't keep up well with such high frequency):



For comparison, below is the PWM of cheap "Ultrafire" flashlight, frequency is only 261Hz, so flicker is very annoying and noticeable:



Color temperature of flashlight is 6976K - a bit on bluish side. CRI is also not too good, about 66. But hey, this is flashlight, not a reading/desk lamp. You can see the spectrum on the picture below. Also note the notch on the blue side of spectrum - this is probably due to protective glass - it cuts out some blue/uv part I assume:



Beamshot looks like this (sorry, no wall with better quality of surface):




Current consumption (from freshly charged battery) in different modes is as follows:

2.26A - "Turbo"
0.8A - "High"
0.4A - "Medium"
0.05A - "Low"


Illumination tests

I've conducted 3 series of tests, at distances of 8 meter, 130 meter and 230 meters.

Camera settings in "indoor" test were locked at level, to not cause overexposure in "turbo" mode:

"Turbo":



"High":



"Medium":



"Low" was barely noticeable at all, so not included.

130 meter tests. In these tests, camera aperture, shutter and iso were configured in the way, to closely reflect the amount of light, seen by human eye in these conditions:

"Turbo":



"High":



"Medium":



"Low" again not noticeable:


230 meters:

"Turbo":



"High":



Other modes just not noticeable:



Other tests:

I've did not conducted a dedicated water test, but when walking on beach, I dropped the flashlight, and it was caught by wave. I quickly took it out. Water didn't reach inside battery compartment or head, but it almost reached MicroUSB port. So this flashlight is definitely not for underwater operation, but it is not rated so.

Conclusion: Excellent quality flashlight for a nice price, with only minor cons, not affecting proper operation of the flashlight.

This flashlight was NOT provided for review, I've spent my very own money to buy it.

Great review with lots of interesting measurements. I especially appreciate the PWM and CRI data. The flashlight itself seems interesting for the price, too bad about the poor LED choice. I think the Eagle Eye X5R beats it in most categories

Thanks. In most cases, it is possible to lower the color temperature, and improve CRI (but of course, by sacrificing total amounts of lumens) if you use CTO gel piece as color filter. CTO (Color To Orange) gels are widely used in tv, movie, photo and etc. areas, when it is needed to match cold fluorescent light color to incandescent. They usually came in grades 1, 1/2, 1/4, 1/8, and does not cost that much - 24x24 inch sheet is about $6 maybe. Single layer of 1/8 CTO gel brings down color by about 1000K, 1/4 - by about 2000K. I have these gels, but usage with this flashlight was impossible, because main are plain, not high temperature gels, so they simply melt, when used on this flashlight.

Some studio shots, forgot to paste them into review:

maukka said:

Great review with lots of interesting measurements. I especially appreciate the PWM and CRI data.

Click to expand...

I agree with these comments by maukka. This is an impressive first outing. The only significant omission is runtime charts, but I understand how hard it is to produce those without an integrating sphere of some sort and logging light meter.

Nice job.

KeepingItLight said:

I agree with these comments by maukka. This is an impressive first outing. The only significant omission is runtime charts, but I understand how hard it is to produce those without an integrating sphere of some sort and logging light meter.

Nice job.

Click to expand...

You don't actually need a sphere to do runtime graphs. Since the beam shape doesn't change at all you only need the relative brightness levels throughout the runtime test. Only a logging light meter is needed (or some patience to check the meter every x minutes). The you just plot your graph with output in % as your Y axis.

Thanks for the suggestions. I haven't measured runtime, because I thought, that it will be different with different battery, so instead, I've measured consumed current in various modes. Knowing capacity of your battery, you can estimate runtime with good precision. Fr example, let's say, we have 2200mAh battery. The estimated runtime in various modes will be:

~1 hour in "turbo" mode
~3 hours in "high" mode
~ 6 hours in "normal" mode
~ 45 hours in "low" mode

I do have integrating sphere and logging multimeter, so building setup to record the actual duration is not that hard. If that is necessary, I can measure it too, and update the review.

On a well-regulated flashlight, output remains constant during a run. Runtime charts for these flashlights show a flat line. If you know output is flat, you don't really need a runtime chart. It's enough to know when the end of a run occurs.

When a flashlight mode has timed step-downs, or is not well-regulated, it is much harder to predict how output will vary over time. That's where a runtime chart really helps.

The following runtime chart contains data for a few flashlights that are well-regulated, and also for a few that are not. Others are well-regulated at the start of a run, but fall out of regulation towards the end. Runtime charts show which is which.

selfbuilt said:

Output/Runtime Graphs:

I previously used AW protected 2200mAh batteries in all my runtime tests, due to their ability to fit and work in every light – and their consistent capacity levels across samples and batches over time. I have been testing a variety of brands of protected NCR18650A (3100mAh capacity) batteries, to see if I can provide compilations that fit in different lights – but show similar performance characteristics. I have found a range of brands that show good correlations and internal consistency, so will now start showing 3100mAh runtimes in my reviews. :wave:

Click to expand...

Different batteries will definitely produce different curves. It is obvious that runtimes with a 3400mAh Li-ion rechargeable will be better (on most flashlights) than runtimes with a 2200mAh battery. That's why flashlight reviewers try to find a good "representative" battery brand, and use that battery type for all their tests. That way, they can compare runtimes of different flashlights. Selfbuilt discusses this above.

Different chemistries will also produce different curves. Below is a startling comparison of alkaline versus NiMH in the Fenix E12.

Trevilux said:

Click to expand...

I figure you already know all this, but it probably doesn't hurt to put it in a post so other readers can see. For me, runtime charts are an important part of a flashlight review.

Beam intensity measurements (i.e., candela measurements) are another.

You, maukka, and perhaps one or two others, are the only reviewers producing hard data on CRI. As a huge fan of high-CRI flashlights, I find those numbers are also a very interesting part of a flashlight review.

Thanks again for producing such an impressive review.

Ok, will do runtime charts and update post asap.

Another idea, how to quickly measure runtime: Flashlight should be connected to adjustable power supply, instead of battery, and output lumens monitored. Supply voltage should be decreased slowly to point, where decrease in brightness will occur. As we now know at which voltage brightness starts to go down, it's absolutely easy to calculate runtime for any given battery.

Great review!
Everything is OK for me but the tint is 6900K
I hate bluish tint.

In fact, during daily usage, that is not that noticeable - if you look at beamshot, center is greenish white and sides are bluish white. In real life, it gives quite good color.