Review: Klarus XT2CR, a slim dual-tailswitch light with USB

This Klarus KT2CR was provided by Going Gear for review. Use coupon code REDDIT for 10% off most lights.

Going Gear's founder, Marshall (/u/storl) passed away recently. In support of his family, all sales at http://olightstore.com today, October 6 only will be donated to Marshall's family.

A full album with extra images is available at https://imgur.com/a/RfaDj

Quick Review

The XT2CR is a new offering from Klarus providing a unique take on the popular dual-switch, USB-charging, straight-tube, 18650-powered segment. This light is aimed at the "tactical" end of the market, and indeed the T word appears five times on the product page. The feature set is, indeed well suited to self defense and law enforcement use: the main switch always turns the light on in high, it's a forward-clicky with half-press for momentary, and the output is appropriate for those use cases.

Unlike any of its comparably-equipped competition, both switches are on the tail, and the power switch does not need to be turned on to charge. This addresses two of the most common complaints about lights in this category. The mode switch can also trigger actions from off, giving the XT2CR shortcuts not usually found in similar lights. There are two mode groups to chose from: "tactical", with 3 brightness levels and a shortcut to strobe on the secondary switch, and "outdoor", with four brightness levels and a shortcut to low on the secondary switch. Both groups always turn on high when the main switch is pressed, and I think even users with tactical needs might find the outdoor group more useful. For those who do like fast access to strobe, it doesn't get faster than in the XT2C's tactical group.

With a protected 18650 battery included and the ability to charge from MicroUSB like most phones, the XT2CR offers an all in one, ready to use package. The charging is reasonably fast, taking about 3 hours to fully charge a battery, and the included battery has as much capacity as any 18650, though not quite the claimed 3600 mAh. All 18650s fit, power and charge inside the XT2CR regardless of button or flat tops or the presence or absence of a protection PCB. The light lacks low-voltage protection and will discharge an unprotected 18650 to 1.0V before shutting off, though it does give warnings with the side indicator light, and eventually blinking the main LED. Caution should be used with unprotected batteries.

The actual light produced by the XT2CR isn't its strong point. There's a a fair amount of it, but the tint is cool white and it is not consistent across the beam. The hotspot is a fairly pure white, but the corona around it has a distinct green tinge, while the edges of the spill are noticeably purple. CRI is unspecified, but most likely around 70. As with most LEDs that don't specifically emphasize color quality, subtle differences in color are a bit washed out, which can be detrimental for quickly identifying people and objects. I'm more critical than the average reviewer about this because I'm hoping to encourage both consumers and manufacturers to pay more attention to color quality. Lumens sell lights, but CRI helps you see.

There's also not as much light as advertised. While I'm a little hesitant to call out manufacturers when my estimating equipment reads a bit lower than advertised, I got 1186 lumens and 218m of throw, which is well below advertised and not meaningfully more than 1x18650, 1" tube lights have been making for years. I'm not surprised, as every 1x18650 XHP35 light I've tested has fallen short of advertised performance. Other reviewers have had similar results with the XHP35, and I'm not sure how otherwise-reputable manufacturers are getting their numbers for these lights. Low is also much higher than advertised at 30 lumens. The boost driver underperforms too, giving lower output on a fresh start with a low battery.

The XT2CR's main selling point is the user interface. It aims to serve both "tactical" and everyday users without significantly compromising either use case, much like the Acebeam L16. I think it largely succeeds, especially if kept in outdoor mode. For users who place a high value on this set of UI features, the XT2CR is a decent choice. For those who care about color quality, or for whom the above-average advertised output is attractive, the XT2CR falls short.

    • Versatile UI suited to multiple use cases.
    • Excellent waterproofing despite having a USB port.
    • Above-average holster included.
    • Well-spaced modes.
    • Versatile with regard to batteries.
    • Cool white, low-CRI.
    • Performance falls well short of advertised specs.
    • Low mode is much higher than advertised, and too high for a lot of use cases.
    • No low-voltage protection, in combination with a boost driver that can damage a battery more quickly than most lights.
    • Output is not stable on the highest mode, despite having a boost driver.
    • Thermal regulation is confused.
    • Severe PWM/ripple on medium.

Details and technical analysis

Accessories

The XT2CR ships with the following:

  • Holster
  • Klarus branded protected 3600 mAh 18650
  • USB cable
  • Pocket clip
  • Lanyard
  • Spare O-rings
  • User manual
  • Warranty card

The holster is of better quality than I'm used to seeing included with lights.

Modes and user interface

There are two mode groups, which are fundamentally similar, but different in the details.

Outdoor group:

State Action Result
Any Half-press main switch Max (momentary)
Any Full-press main switch Max (steady)
Off Short-press mode switch Low (momentary)
Off Long-press mode switch Low (steady)
On Mode switch Change modes (L -> H
On (main switch only) Long-press mode switch SOS

Tactical group:

State Action Result
Any Half-press main switch Max (momentary)
Any Full-press main switch Max (steady)
Off Short-press mode switch Strobe (momentary)
Off Long-press mode switch Strobe (steady)
On Mode switch Change modes (H -> L
On (main switch only) Long-press mode switch strobe

To switch between groups, hold down the mode switch until the side indicator light blinks, then press the main switch.

Output and runtime

All tests were conducted with an LG HG2 3000 mAh 18650 battery unless otherwise noted. Advertised runitmes are with the included "3600 mAh" Klarus battery.

Mode Advertised Lumens Estimated Lumens Throw (FL1 meters) Graph Advertised Runtime Time to 80% Time to 50% Time to 10% Tailcap current (mA)
Standby 0 0 0 - - - - 1 year 375 microamps
Low 10 30 35 - 200 hours - - - -
Medium 100 76 60 - 14 hours - - - -
High 400 388 123 graph 240 min 159 min 159 min 170 min -
Turbo 1600 1186 222 graph 72 min 1 min 1 min 98 min -

The standby current is high enough to drain the battery in about a year. That's excessive, and two orders of magnitude above what I've seen from some budget e-switch lights as well as premium competition like Armytek. Loosening the tailcap isn't a full mechanical lockout and may not eliminate the standby drain. This light should not be stored long-term with batteries installed. The unusual design of this light prevented me from measuring current with the light on.

Outputs were not meaningfully different the using supplied Klarus "3600 mAh" battery, a Sony VTC6, one of the most capable high-drain cells on the market, nor with two Aspire INR high-drain 18350s. Starting the light with a 3.7V battery results in an initial output of 750lm, climbing slowly to 900, then decreasing again. This is unusual behavior from a boost driver that I can't recall observing with any other light. It does provide full output on lower modes, but fails to do so on max, which is one of the usual advantages of a boost driver. There was thermal throttling even with water cooling, which kept the light cool to the touch. Either there's a thermal path issue, or Klarus didn't anticipate anybody keeping this light cool enough.

Lights that use the XHP35 emitter with a single 18650 often perform significantly worse than advertised. The best one I've tested, the Acebeam L16 fell short by 15% on output and throw. The Armytek Prime Pro fell short of its advertised output by a much larger margin, even more than the XT2CR does. I'm disappointed to see otherwise-reputable companies advertising numbers that are simply wishful thinking. I'm not convinced that this emitter, requiring a 3-4x voltage boost is a good idea for 1x18650 lights, as the advertised output is usually possible with a much smaller voltage boost simply by driving a 3V emitter hard.

Additional graphs:

Light quality

Some current ripple is detectable using a smartphone with manual shutter speed, especially on the medium mode. Adjusting shutter speed suggests a frequency around 500 Hz, and there's a visible stop-motion effect when waving my hand in front of the light in medium, but not other modes. This effect will interfere with most smartphone cameras and many other compact image capture devices, such as body cameras. The most affected mode is absent from the tactical mode group.

The beam is cool white. The center is a fairly pure cool white, but the corona is green and the outer spill is a bit purple. CRI is unspecified, but probably right around 70. This is not a beautiful beam.

Ergonomics

The XT2CR is as comfortable to hold in the hand as any 1" tube light. The anodizing is smooth, with some light checkering in the center section. Grip is adequate, but not exceptional. The buttons are fairly easy to press, however the wings on the sides can interfere. They're not quite large enough, however for reliable tailstanding. I would have preferred that Klarus pick one or the other.

The pocket clip holds securely without destroying clothing, however it's positioned unusually far down the body of the light. It's a loopover design, but does not make any attempt to increase carry depth. The result is over an inch of tailcap sticking out of the pocket. While I don't ordinarily prefer especially deep carry, as I want my EDC gear to be easy to get out, this takes it too far. I tried using an Armytek Wizard clip and succeeded only in scratching the XT2CR's finish, though a similar clip in slightly narrower metal would work.

Battery and charging

The included batter is a protected button top claiming 3600 mAh. I measured 3400, which is about what I expected to find. I suspect the cell is the rare Sanyo NCR18650G, which claimed 3600 mAh, but didn't perform as well as the NCR18650GA, which claims 3500. Aside from being slighly off in advertised capacity, this battery is fine.

Charging takes 3 hours with an HG2 that was run down to the light's low-voltage warning and a 1.8A MicroUSB charger, an average charge rate of 1A. The first 2 hours or more are likely at a higher rate, because current is reduced near the end of a Li-ion charge cycle.

The XT2CR can use and charge any standard 18650 battery, with or without protection circuits or button tops. As it lacks hard low-voltage protection, care must be used with unprotected cells. There is sufficient warning when the battery is low, but the XT2CR's boost driver can and will over-discharge a cell if allowed to. There's some battery rattle if the light is shaken with an unprotected flat-top, but it does not break contact.

Two CR123s, 16340s or 18350s may be used. I'm not sure if there's any warning about low-voltage with two Li-ions and would recommend against using that configuration outside of an emergency.

Modification potential

I've decided to start including modifications in reviews. Some people just can't leave well enough alone, and I'm one of them.

The steel bezel is easily removed from the XT2CR, intended to be replaceable with a more aggressive version. This does not allow access to any internal components, however. The forward section of the head is held in place by glue, which I was able to defeat using boiling water and a strap wrench.

  • https://imgur.com/AUsOV0f.jpg
  • https://imgur.com/ZYrhVnk.jpg

As I want to post the review today to further promote the benefit for Marshall's family, I will try emitter swaps later and make a separate post, as well as updating this review. 12V emitter options that seem viable include other variants of XHP35, the XHP50 and XHP50.2 if there's a spacer/centering ring option that works well, and the Nichia 144AR, with similar spacing considerations. I expect an XHP35 HI to make the nicest beam out of those, and Kaidomain does offer them in 80 CRI and a couple tints.