Klarus G20 review (26650, XHP70)

maukka

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Dec 22, 2015
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641
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Klarus G20 is one of the more compact 26650 lights out there. With an integrated usb charging and XHP70 LED it's advertised to reach 3000 lumens, which puts it in the same ballpark with other similar lights such as the Olight R50 Pro and Acebeam EC50 II.

Features and manufacturer's specifications
Battery: 26650, the light comes bundled with a protected battery
LED: Cree XHP70 N4, cool white
Waterproof: IPX8, 2m
Mode memory: yes (side switch)

Manufacturer's output specs
Maximum output: 3000 lumens
Other output levels: 650/160/15 lumens
Light intensity: 5625 candela
Beam distance: 150 m

Measured dimensions and weight
Length: 123.8 mm
Head width: 37.2 mm
Handle width: 34.4 mm
Weight: 132 g for the light and 97 g for the battery

User interface
From off:
Click side switch to turn on the light on the last mode used
Click tail switch to turn on the light on low
Long press and hold either switch for momentary turbo, releasing the switch turns the light off
Double click for strobe (alternating frequency)
Hold both switches for two seconds to lock them out, fast triple click of either switch unlocks them

From on:
Click side or tail switch to advance to the next brightness mode (low-mid-high-turbo-low...)
Long press to turn off the light
- Keep holding for momentary turbo, return to the previous mode when you let go of the switch
Double click for strobe (alternating frequency)
Hold both switches for two seconds to lock them out, fast triple click of either switch unlocks them

If I remember correctly the instant access to turbo from off and on seems to have changed from previous versions of the G20, where it would stay on turbo after you let go of the switch. In my sample there's no way to remain on turbo if it was accessed with the long press and hold, which in my eyes is a minus. I however like that there's the option of always turning the light on on the lowest mode with the tail switch while still having mode memory on the side switch. Having turbo on the basic cycle is also a plus and makes the light easy to use for anyone.

Box and contents

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Bundled in the box:
5000 mAh 26650 battery (inside the light)
Lanyard
Micro usb charging cable
Holster
Spare o-ring
User manual

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The cool white Cree XHP70 led is located in a small shallow orange peel reflector. The lens is protected by a thick steel bezel.

Battery and usb charging

The bundled 5000 mAh 26650 battery is protected but not proprietary. You can charge it in any lithium ion charger and also use and charge any 26650 battery in the G20. Springs at both ends of the tube makes it easy to use any sort of batteries.

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The threads are unanodized, so physical lockout is not possible. Electronic lockout is available but it doesn't prevent standby battery drain.

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Klarus 5000 mAh 26650 measurements
Length: 71.0 mm
Width: 26.6 mm
Weight: 97 g
Protected: yes
Capacity: 5104 mAh
Energy: 18.098 Wh
Average voltage: 3.543 V
Internal resistance: 0.046 ohm
Over current protection: 13.6 A
Low voltage protection: <2.5 V

Capacity was measured at 1 amp down to 2.5 volts after being charged to 4.20 volts at 2 amps.

The battery has good capacity but quite a high internal resistance (0.046 ohm) for a 26650, but the latter doesn't seem to affect the maximum performance of the G20. I wasn't able to increase the maximum output with higher performing batteries (Liitokala 0.030 ohm, Vappower 0.029 ohm).

The cause for the high IR is of course the integrated protection circuit. It has an over current protection at 13.6 amps. To reset the protection, you just need to take it out of the device for a second, but naturally the protection never kicks in in the G20 since it doesn't draw that much. I didn't measure the current draw of the G20.

The low voltage protection is below 2.5 volts and never activated during my runtime tests.

The battery can be charged inside the G20 through the ubiquitous micro usb port.

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The usb charging port is located in the head behind a rubber cover. The port opening is quite tight, so some big connectors might not fit. I had no trouble with the cables I had at hand.

The charging circuit draws anywhere from 0.16 to 1.9 amps from a usb power source. The current depends heavily on the output voltage. In my opinion the charging circuit is a bit too picky about the input voltage. Especially because the supplied usb cable does have higher than optimal resistance (0.20 ohm), which lowers the voltage under load. Using the supplied cable makes it difficult to charge the battery at over 1 amps.

Here are two charging events with different chargers and cables.

Blitzwolf BW-S7 from its QuickCharge 3.0 port with a 15 cm low resistance usb cable. Max 1.9 A.
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Aukey PA-Y5 using the cable supplied with the G20. Max 0.95 A.
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As you can see, the time it takes to fully charge the battery varies a lot (3h 13min vs. 5h 40min) even though both chargers are able to supply over 5 volts under load. I wouldn't be surprised by 10 hours charging times using some usb chargers or power banks with long cables.

The charging terminates at 0,30-0,37 A, a bit prematurely in my opinion, and charges the cell to 4,22 volts (within spec).

Size comparison

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Klarus 5000 mAh 26650 battery, Klarus G20, Olight R50 Pro, Acebeam EC50 II, Eagle Eye X7, Acebeam EC60.

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While the handle part is pretty much the same diameter in all the 26650 lights, the shorter length and thinner head make the G20 feel quite significantly smaller. It's also very light at 229 grams. What really sets the G20 apart though is its dual electronic switch system. The only difference between them is that the side switch has mode memory, the tailcap doesn't.

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Klarus G20, Olight R50 Pro, Acebeam EC50 all sporting a Cree XHP70.

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Klarus has the narrowest reflector of the XHP70 lights compared here (G20, R50 Pro, EC50 II). This results in a wide hotspot and spill as can be seen from the beamshots below.

Beamshot comparisons

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Hotspot and spill. The G20 and R50 Pro have identical tint (and the not so pretty shift from green to cool), but the G20's hotspot is much wider. The neutral version of the EC50 II is clearly warmer and similar to the Nitecore EC4SW which sports the older but beautifully neutral MT-G20 led.
Individual jpegs: G20, R50 Pro, EC50 II, EC4SW

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Spill comparison. Spill width is almost identical on the G20 and the R50 Pro.
Individual jpegs: G20, R50 Pro, EC50 II, EC4SW

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Real life usage. The G20 lights up your close vicinity very well. The R50 Pro has significantly more throw with the more focused hot spot. The spot is much harder to see on the EC50 II and the EC4SW.
Individual jpegs: G20, R50 Pro, EC50 II, EC4SW

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Individual jpegs: G20, R50 Pro, EC50 II, EC4SW

All in all the G20 has a very usable and a floody beam shape. My usual gripe about the XHP70 tint shift applies and I wished Klarus offered the light in a neutral or warm version as well.

Beam, tint and color rendering

Just like in most XHP70 lights going for max output, the beam has a greenish tint in the hotspot and bluish in the spill combined with a low color rendering index. On lower modes the tint shifts even more towards green.

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Color temperature in different parts of the beam.

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Tint in different parts of the beam.

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Tint in different brightness modes.

Spectral data and color rendering

For spectral information and CRI calculations I use an X-rite i1Pro spectrophotometer with HCFR, Babelcolor CT&A and ArgyllCMS spotread for the graphs and data. For runtime tests I use spotread with a custom script and an i1Display Pro because it doesn't require calibration every 30 minutes like the i1Pro.

Explanation of abbreviations (click link to read more)

CCT = correlated color temperature, higher temperature means cooler (bluish)
CRI (Ra) = color rendering index consisting of 8 different colors (R1-R8), max value 100
CRI (R9) = color rendering index with deep red, usually difficult for led based light sources, max value 100
TLCI = television lighting consistency index, max value 100
CQS (Qa) = Proposed replacement for CRI, RMS average of 15 color samples
CRI2012 (Ra,2012) = Another proposed replacement for CRI, consists of 17 color samples
MCRI = Color rendering index based on the memory of colors or 9 familiar objects
NEW Read more about the IES TM-30-15 method here (link is external)
TM-30 = The newest color rendering method using 99 samples. Preferred for comparing LEDs.
TM-30 (Rf) = Accuracy of colors, fidelity index. Replaces CRI(Ra).
TM-30 (Rg) = Gamut of colors, saturation index. Higher number means more saturated colors.
Tint dev. ("Duv" in the CTA screenshots) is the tint's distance to the black body radiator line in the CIE graphs. The higher the number, the greener the tint. 0,0000 means absolutely neutral white and negative numbers mean rosy/magenta tint. Anything over 0,0100 can be described as visibly green.

If you have an hour to spare, I recommend watching this presentation on IES TM-30-15 which also shines light into color rendering in general.



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Color rendering on turbo.

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Color rendering comparison.

Runtimes and output
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The G20 can't quite match other heavier lights in maximum output and falls short of the claimed 3000 lumens. There's a stepdown at two minutes and some bouncing from temperature regulation regardless of cooling. The output doesn't improve with unprotected high current batteries.

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When uncooled, there's practically no difference between the lights in sustained use.

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When cooled, the turbo output steadies initially at a higher level. The body gets to about 50°C max, which is perfect for not burning your hands.

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Here's the Klarus on high, Olight and Acebeam on mid. There's practically no difference in efficacy or output between the Acebeam and Klarus. But since the Acebeam uses a neutral white XHP70 with less lumens per watt, the driver advantage goes to Acebeam (the 26650 batteries are identical in capacity). The Olight is more efficient than both of them though.

PWM

No PWM on any mode.

Standby current
I measured 520 microamps of parasitic drain, which results in the 5000 mAh battery draining in about a year.

Lately there has been some worry over the electronic lockouts increasing parasitic drain. I left the battery into the G20 for 4 weeks (28 days) with the electronic lockout activated. After sitting on the shelf the battery read 4.08 volts and during recharging it took in 420 mAh which averages out to the 5100 mAh battery discharging completely in about a year (5100mAh/420mAh*28d=340d). Of course the standby current may increase on lower battery voltage to keep power draw constant, but in practice the lockout mode doesn't have a meaningful effect to the parasitic drain.


Since the threads are not anodized, there's no physical lockout. I recommend removing the battery altogether when not using the light for prolonged periods.

Verdict

Taking in to consideration the smaller size and significantly lower price than its closest competitors, the Klarus G20 is a good purchase. That is if you don't mind the cool white XHP70 with its usual shortcomings (low CRI, greenish tint, tint shift). I would also always like to see a neutral white option from manufacturers. Maximum output doesn't quite match the R50 Pro or EC50 II, but they all step down after a while to the same level.

The wide beam lights up your feet well when hiking and is well suited for close up and medium distance use. The narrow and shallow reflector understandably makes for only a mediocre throw distance of about 160 meters.

The user interface is very easy to learn and the switches feel very nice and clicky. The long click to turn off the light might be a problem for some, but more importantly the G20 is very easy to use. Usually I don't like it when strobe is activated with a double click, since it is easy to enter unintended when cycling modes, but on the G20 the double click is set fast enough. The double switch system is very useful, just use the tailcap switch during the night to turn it on low if you don't remember which mode you used last.

Usb charging is a bonus, but the circuit is very picky about the input voltage. Expect charging times anywhere from three to ten hours. I'm happy that the light has a low voltage protection on its own, so it's no problem using unprotected batteries. All 26650s are compatible and can be charged in the light. The bundled 5000 mAh battery can be used in other lights as well. I'm not so happy about the standby drain that empties the battery in about a year. Especially combined with the unanodized threads.

+ Small size
+ Useful wide beam shape
+ Good clicky feel of the switches
+ Easy user interface and two switches
+ Low voltage protection on the light
+ Standard 26650 battery
+ No PWM
+ Doesn't get hotter than 50°C
- Charging time depends heavily on the input voltage from the usb charger
- XHP70 has greenish hotspot and bluish spill
- No neutral white option
- Mediocre throw distance
- Standby battery drain is quite high
- No physical lockout
 
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Mp0w3r

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Joined
Feb 13, 2017
Messages
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Wow great review, I agree I wish they offered a NW option
 

maukka

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Joined
Dec 22, 2015
Messages
641
Location
Finland
Lately there has been some worry over the electronic lockouts increasing parasitic drain. I left the battery into the G20 for 4 weeks (28 days) with the electronic lockout activated. After sitting on the shelf the battery read 4.08 volts and during recharging it took in 420 mAh which averages out to the 5100 mAh battery discharging completely in about a year (5100mAh/420mAh*28d=340d). Of course the standby current may increase on lower battery voltage to keep power draw constant, but in practice the lockout mode doesn't have a meaningful effect to the parasitic drain. You should remove the battery if left unused for longer periods.
 

maukka

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Joined
Dec 22, 2015
Messages
641
Location
Finland
I highly suggest dedoming and possibly swapping the emitter to a bit warmer and higher CRI one if you decide to get the G20.

The emitter is on a small copper MCPCB. The thermal sensor seems to be attached to the shelf, which explains the ringing in the output when the light adjusts its output. The temperature changes are faster than if it was positioned on the driver for example.

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With the change the beam becomes very consistent, the hotspot and spill are almost identical in tint and there's no artifacts either.

I swapped a CRI80+ 4500 K XHP70 onto mine (Cree part XHP70A-01-0000-0D0HM245G). Here's the results with the stock LED, the 4500 K LED and lastly the new LED with a sliced dome (I used a razor blade).

I wasn't happy at all with just the emitter swap, since the huge tint shift (greenish yellow to blue) was still there. Slicing the dome fixed that right up and the beam is now excellent!

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Since my original G20 had pretty much identical tint and tint shift to my sample of the Olight R50 Pro Seeker, here's beamshots from that and the newly modded G20 with a sliced dome using the same camera settings (with a slight desaturation of the R50 image to make it look more realistic).

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CRI Data reveals that the new emitter is actually CRI80, but the hotspot was terribly tinted towards yellow/green (duv 0.009). It was also much warmer than specified (4000 K vs. 4500 K), but this seems to be often the case when measured from the hotspot in a flashlight with a reflector.

First, the new emitter with the dome intact.

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And with the dome sliced off things look much better. More neutral (duv 0.004). And as expected, a slightly warmer hotspot at 3900 K. CRI dropped by one at that particular position of the beam, no worries, it was back to 80 on the next spot I measured.

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Output at 30 sec changed as follows:
Stock: 2200 lumens
4500 K: 1990 lumens
Dedomed: 1760 lumens

A sacrifice I'm more than willing to make for the prettier beam. I didn't measure lux, but the hotspot was clearly brighter after dedoming the 4500 K LED. Getting more throw wasn't the goal of this exercise. Now the light quality is actually superb and Klarus should offer it with a dedomed XHP70 (like every other manufacturer). I hoped Cree would also manufacture XHP50/70 with no dome, but I guess flashlight industry isn't big enough. In my opinion the beam quality always improves after dedoming when using these.

The finished mod.

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jetslipper

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Joined
Apr 20, 2014
Messages
37
🤗 your "surgery" of the XHP70 went rather well, congratulations maukka! That tint looks way better than the stock G20 (and the R50 Pro). By the way, have you measured the beam intensity of the de-domed XHP70? (Actually, I did notice you said you didn't measure the lux. Maybe some other time.)
 
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maukka

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Dec 22, 2015
Messages
641
Location
Finland
Also, remember to always pick an emitter that is 500 K higher than your preferred color temp. The dedoming itself doesn't really affect the hotspot color temperature more so the spill. Most of the XHP70s I've bought seem to read 500 K lower when used with a reflector. If I did this again I probably would choose a 5000 K one for this project, since 4500 K is my favorite.
 
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