[selfbuilt]

DarkTort DT-E1.0 Review: RUNTIMES, BEAMSHOTS, DETAILED PICS, and more!

Reviewer's note: the DarkTort DT-E1.0 was supplied for review by DarkTort. Please their manufacturer's thread on CPFMP for more info.

Warning: pic heavy!

UPDATE JANUARY 4, 2009: Additional pics and info have been added to the review, based on feedback from DarkTort. See also my response posts later in this thread.

Manufacturer’s reported specs:

• CREE Q5 WC, maximum output 225 lumens.
• PWM-based low output.
• Battery discharge protection mode.
• Three-stage (high, low, strobe) light modes.
• IC efficiency up to 96%.
• Anti-rolling rugged design.
• Impact-resistant optical window with Dual-Coating technique.
• Mil-spec Type III Hard Anodized finish.
• Impact and drop-resistant according to US-MIL-STD-810F.
• Waterproof to IPX-8 standard.
• Forward clicky.
• Length: 140mm, Head diameter: 32, Body diameter: 25.5mm, Weight: 168g
• Package: Gift box
• Battery: Only 18650
• Lanyard: Taiwan MagForce
• Flashlight body available can be disassembled, users can change the emitter.

DarkTort is a new arrival to the flashlight scene, and the DT-E1.0 is their first flashlight. Note that this light is 18650-only. MSRP is ~$75.

Let’s get right to the pics:




The light comes in a good quality hard case with metal closing clasp. Sandwiched between the textured foam pieces is the light, extra o-rings, and good quality wrist lanyard. Located under the bottom foam piece is the manual and warranty card.

Does this packaging look familiar? Here’s a blow-up from a page of the manual as well:



Maybe it’s just me, but this looks a LOT like the Edgetac/Nitecore packaging for their lights. Even the o-rings look the same. Interestingly, DarkTort also uses the same viscous blue lube that Edgetac does (and too much of it – again, sound familiar? )




The DT-E1.0 is a visually interesting light to look at. The stainless steel bezel is a nice touch, engraved with the company logo. Anodizing is a flawless dark black on my sample, and lettering is sharp and clear. A number of labels are present on the body, to indicate battery orientation and light mode switching, in addition to a good number of identification labels (again, sound like the first products of another manufacturer we know? ).



As you see can see, the head has an unusual contact surface. Pics in DarkTort’s CPFMP thread show more detail of the internal components, but I haven’t been able to open the head by hand. I’ll have to break out the strap wrenches later and give it a go. Here’s what the business end looks like:



Now that’s interesting – it appears that the red aluminum pieces show through at the base of the reflector. Very stylish. Reflector is OP textured, and fairly deep. According to specs, the emitter is a Cree Q5 premium WC tint.

UPDATE: I managed to open the head by hand, using a cloth around the bezel (strap wrenches weren't necessary). Here' what you'll find:




Nice construction here - note the o-rings at both along the lens inside the stainless steel bezel ring and at the base of the screw threads on the head piece. The reflector looks like a solid piece of metal. But be warned that the reflector and emitter/pill are not screwed it - they will both just fall out if you tip the head over once the stainless steel bezel ring is removed.

I have disassembled the screws holding the pill unit together - see the end of this review for detailed pics. Those 3 contacts points in the head are indeed mounted on springs, and control the Hi/Lo sensors for the head twist.



The tail region is unusual. Although you can lock the light out by twisting the tailcap (anodized threads), you can’t insert/remove the battery this way. The battery can only be exchanged by unscrewing the head portion. The tail region is not wide enough to allow a battery to pass through, like you find on a number of Surefire lights.

Body tube width is ample to accommodate my protected AW 18650 batteries. In fact, with room to space - I can detect some battery rattle when shaking the light.



The tail switch is a forward clicky – press for momentary on, click to lock-on. The traverse is longer than more clicky lights, and I find mine is a little “squishy” (i.e. you aren’t always sure if you’ve pressed it enough for it to lock-on, and it sometimes feels like it’s not fully secure).

Note the switch retaining ring is metal in the centre, but plastic for the portion that screws into the tailcap.

UPDATE: DarkTort has announced a new switch assembly for all currently shipping DT-E1.0 lights. Details are available in the CPFMP thread, post 213.

Here's how it fits in my hand (note that I have relatively long fingers ).



As for dimensions, my sample is 141.8mm (length) by 32.3mm (head width) or 25.1mm (tailcap width) – consistent with manufacturer specs.

Weight without battery is 119.5g, which is less than manufacturer’s claim (UPDATE: DarkTort has now revised their estimate to match mine).

Here’s how it compares to the competition:


From left to right: AW 18650, DarkTort DT-E1.0, JetBeam Jet-III M, Jet-III ST, Edgetac Raidfire Spear, Olight T20, Olight M20 Warrior.

As you can see, it’s about the same size as the Jet-III M or Olight M20. As such, I’ve used those two lights for the beamshots below. All lights on max on 18650, ~0.5 m from a white wall.






As you can see, the DT-E1.0 is quite bright on 18650 (more on that later). Beam profile is very similar to those lights, although the DT-E1.0 seems a little less ringy to me.

User Interface

The UI is quite simple: tighten the head for Hi, loosen slightly for Lo. To activate the strobe, simply do a rapid loosen-tighten switch from Hi mode. I haven’t measured the strobe freq yet, but it is definitely one of the highest I’ve seen (i.e. quite “tactical”).

Press the forward clicky for momentary on, click for lock-on.

Testing Method: All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. 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. Throw values are the square-root of lux measurements taken at 1 meter from the lens, using a light meter (peak throw is determined for each light, and reported here).

Throw/Output Summary Chart:



Ok, one of the first things to notice: DT-E1.0 initial Hi output is one of the highest I’ve ever seen for a Q5 light. It’s neck-and-neck to my Raidfire Spear by ceiling bounce, and has the highest reading yet in my lightbox.

Throw is under 10K lux (which is less than the near 16K lux reported by the manufacturer) but within the range of other lights of this size.

UPDATE: Shipping versions with have a Lo mode output that is half what was shown here, see explanation in runtime section.

Output/Runtime Comparison:

First off – how does this light compare to the other 18650-only competition?



Now that’s interesting! Unlike the other 18650-only lights, the DT-E1.0 is not fully regulated on Hi. In fact, that’s a rather unique runtime pattern – it seems to slowly decay from max, then briefly jumps back up to max before dropping down.

But here’s the next interesting bit – it doesn’t drop to zero output or simply fall out of regulation the way all the other 18650-only lights do. Instead, it drops to a regulated low output around ~2% of max. I ran the light for over 3 hours at this min level, and it was still going strong!

You’ll also note that the light runs a lot longer on 18650 than my regulated 18650-only lights do. Given the interesting trace, I thought I’d compare it to multi-power lights on 18650. Note that virtually all multi-power lights are direct drive on 18650:



Well, well, what do you know – the DT-E1.0 trace looks an awful lot like direct-drive, until the blip near the end. The difference is that the DT-E1.0 appears to be the most heavily-driven direct-drive light on 18650 I’ve seen yet.

How about the low mode?



I haven’t done a lot of low mode runtime tests to compare, but the ~11hr regulated runtime seems a bit on the low side to me for a defined output light (i.e. that's more what I would expect for a continuously-variable PWM light). It is also less than the 18hr runtime the manufacturer reports.

Note again that the light goes into the regulated “moon mode” low light level at the end of the run. It lasted for ~1.5 hours at this level before the cell's protection circuit was tripped (UPDATE: I've updated the runtime above to show you when it actually cut-off - hit your browser refresh if it doesn't show).

UPDATE: DarkTort reports that these early review samples erroneously had a MCU adjusted to twice normal output for the Lo mode, hence the shorter runtimes than what they reported (i.e. this sample's Lo is reported to be 20% of max, but shipping version should be 10% of max as originally proposed). If that is indeed the case, I would expect at least twice the runtime at the lower output level.

Potential Issues

Aside from the lack of true regulation on Hi, the only real efficiency issue I’ve noticed is the slightly short regulated runtime on Lo.

The tail switch clicky feels a little “squishy” on mine (i.e. you aren’t always sure if you’ve pressed it enough for it to lock-on, and it sometimes feels like it’s not fully secure).

UPDATE 01/12/09: In response to CPF user feedback about the poor switch feel, DartTort has announced a new design that will be included from now on with all shipping lights. Details and pic posted in their CPFMP thread here.

General Observations

There’s no doubt that the DT-E1.0 is an impressive looking light that comes in a nice package. As a first offering nowadays, it’s a bit unusual to come out with an 18650-only light with just 2 output modes (plus strobe). But I’m sure the KISS principle and stylish design will be appreciated by many.

The most unusual aspect of this light is the circuit performance. I know a lot people will decry the seemingly direct-drive pattern on Hi – but take a closer look at the 18650-only runtime comparison graph. As you’ll see, the DT-E1.0 produces more light for longer than any of my fully-regulated 18650-only lights in my collection.

This really is the best of both worlds, IMO – the most maximally-driven and efficient setup on Hi I’ve seen in a 18650 Q5 light.

The Lo mode is actually quite bright and useful in its own right. Better than the Raidfire Spear’s extreme low, in comparison. But the runtime efficiency at this level seems a little low on my sample.

Regardless of how you feel about the defined output level runtime patterns, the regulated minimum level when the battery is near exhaustion is something I’ve not seen before. Usually, you hit the battery protection circuit like a brick wall, or else you drop out of regulation for a low moon mode. This regulated moon mode is a welcome new addition to the scene. Note too that DarkTort claims to have a built-in battery protection feature – unfortunately, I don’t have any unprotected 18650s to test that with.

For a first offering, this light suggests to me that DarkTort knows how to make high quality lights that are not run-of-the-mill. I'm curious to see what they come out with next.

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UPDATE JANUARY 5, 2009:

For those curious about modding the existing pill, here's what I found when I disassembled the pill:



As you can see, the emitter is easily accessed by removing the 3 screws on the cover plate. Looks like they used a good amount of thermal epoxy, but you should be able to pop out the mini-star for a DIY emitter swap pretty easily (with basic modding skills and components).



The circuit board is also easy to access should you want to. But be warned - the contact retaining plate is attached under pressure (i.e. the 3 longer screws are holding the plate in place, against the resistance of the 3 springs used to control mode switching).

I found it a real pain to re-attach this plate, as you need to carefully tighten each screw while gently but firmly holding it all together against the springs (recall the exposed emitter dome at the other end of the pill!). When tightening the screws, it's easy for the plate to slip sideways a little - which then makes it impossible to fit back into the head, because tolerances are tight.

Remember that the pill assembly is not screwed in - pressure is maintained by the bezel ring/lens pressing down on the reflector, which in turn presses down on the pill assembly. On the plus side, a manufacturer upgrade of the entire pill assembly (i.e the entire red aluminum section) would be child's play for anyone to swap on their own.