Custom Convoy M1 Build Review – SST-20 4000K, H17Fx, Forward Clicky, Switchback

This content originally appeared on Reddit on May 15, 2021.

Introduction & Parts List

Obviously you can’t just go out and buy this light, but I enjoy writing these and it can serve as a review of the individual parts too, so here’s my review. Total cost was about $70 after shipping and taxes and all that. Here are the parts I used and where I bought them:

• Host: Convoy M1 Host
• Emitter: SST-20 4000K 95CRI on a 20mm MCPCB
• Driver: Mountain Electronics H17Fx
• Switch: Mountain Electronics 17mm Forward Clicky
• Clip: Thyrm Switchback 2.0

Size & Host

Emisar D4V2 | Noctigon KR1 | Wurkkos WK30 | Convoy M1 | Convoy Z1

Part	Measurement (mm)
Bezel Diameter	35.5
Body Diameter (at knurling)	24.8
Length	139

In the pocket it just feels like a slightly longer and less dense Noctigon KR1. It’s perfectly carriable, but it won’t “disappear in the pocket”. If you would like any specific measurements, please don’t hesitate to ask. If I still have the light I’ll be happy to oblige.

The Convoy M1 is pretty great. I love the looks and shape of it. It feels great in hand, especially with the Switchback installed on it. I do have two very minor things I think can be improved though. First is that the threads for the head & tail feel really shallow and wide. They’re hard to line up and get started. Cross-threading hasn’t been an issue, the threads just don’t bite very easily. Switching to some deeper threads like the new S2+ threads in the future would be a nice improvement. The other issue is that the retaining ring in the head is a very thin piece of aluminum and the holes drilled in it weren’t big enough to fit my snap ring pliers into. Fortunately it wasn’t tightened down when I received it so I was able to remove it and enlarge the holes myself. I think including a beefier, brass retaining ring in the future would be good.

User Interface & Driver

The H17Fx driver I used uses the Lucidrv2 firmware. It’s way too feature rich to get into here, but I’ll describe how I have it configured with the forward clicky switch. If you want more details, check out the H17Fx official product page.

State	Action	Result
off	half-press	momentary (moonlight)
off	click	on (moonlight)
off	quick double half-press	high
off	multiple slow half-presses	cycle modes (ml-low-med-high)
on	click	off
on	half-press	no action
off	8+ quick half presses	battery check/programming mode

I really like the UI of this light and Lucidrv2. From a programming standpoint it’s clearly designed for use with a reverse clicky, but it’s not hard to do with a forward clicky switch either. I love the double tap function. I don’t like mode memory but I also don’t want to have to cycle through up to 7 different modes to get to the highest one. This double tap for high I have set up works really well. I also quite like that you can add/subtract/customize the modes instead of having to select from some pre-defined mode groups. That means I can choose exactly how many modes I want, what modes I want, and what order they’re in. I have mine set to what I think is a pretty logical moonlight-low-medium-high, but if you wanted to go crazy you could do low-tactical strobe-high-bike flasher-medium. You can customize the max temperature setting, but I found the stock setting of 60C worked best. Once the light is thermally saturated it’s still plenty holdable. I think I would have preferred a customizable timed stepdown to a constant power level rather than thermal regulation, but that’s such a minor thing it honestly doesn’t bother me.

The driver itself I’m less enthused about. It’s good, but I find it lacking a little bit on the high end and the low end. I’m growing to dislike FET drive. If I turn my light on its highest brightness setting, I want it to be the same brightness whether I’m using a full cell or a mostly depleted one and that doesn’t work with FET drive. This driver has a FET channel but I’ve elected not to use it. That leaves the highest current it can output at about 3 amps. That’s OK and will give you enough brightness, but not a *lot* of brightness. I would have liked to see it regulated up to 5 amps or so. That’s where the SST-20 I’ve used here hits about 1000 lumens and I think that’s a great amount of output for a light this size and this style.

I also find the moonlight mode disappointing. This driver can provide some incredibly dim moonlight levels which is brilliant, but they stop working as your battery gets lower. The moonlight mode I want to use on this light stops working below 3.8V, so I’m left wondering why my light isn’t working, then switching to “low” which is much brighter. I changed the moonlight mode to the lowest level I could get to work reliably with a mostly depleted cell. It’s still good for a moonlight mode, not too bright, and much better than the 30 lumen lowest mode of the last switchback host I had, but I would definitely like it to be dimmer. If I had to guess, the level I’m using is probably around 1.5 lumens or so.

The final issue I had was that the voltage readout appeared to incorrect. I don’t believe the issue is with the actual sensor because low voltage stepdowns kicked in right on cue at 3 volts. The light is supposed to blink between 1 and 10 times to read out voltage; one blink for every 0.12v above 3v. However, anytime I used the voltage readout built into the light, it consistently read one or two blinks higher than I measured with my multimeter (except with a fully charged cell, since it won’t blink more than 10 times). Once you know about this issue, you can just correct for the error, but it’s technically still an issue nonetheless.

I believe the LED4POWER LD-A4 might be a suitable upgrade from the H17Fx. It retains the highly programmable nature of the driver and the quick double-tap shortcut, but it is available with a much higher regulated output and hopefully a lower and more reliable moonlight mode as well. I may pick one up and try it out. It does require you to have an MCPCB with a temp sensor on it though, rather than it being on the driver. Fortunately, LED4POWER sells those.

Output & Modes

Lumens: I don’t have a way of measuring lumens, but with the combination of the 3A current from the driver and the SST-20 4000K emitter, it should be putting out somewhere around 700 lumens on high. I’d describe it as “plenty” but not “wow” bright. I’d like to be able to push the emitter up to 5A to get ~1000lm out of it.

Candela & Throw: With the ceilingbounce app on my phone I measured just under 30,000 candela (346 Meters ANSI) and that seems about right to my eye. Nice and throwy.

Levels: The modes on this light are highly customizable. I chose to have 4 modes: moonlight, low, medium, and high. I set high mode to the highest regulated level (level 22). Then I set my moonlight mode to the lowest mode that would work with a mostly depleted cell (level 4). Then I set low and medium to levels that would provide even mode spacing (levels 10 and 16, respectively). I’ve estimated the lumens below based on relative output compared to high mode, which I estimate at 700 lumens.

Mode	Lumens (estimated)	Current draw at tailcap (ma)
Moonlight	too low to calculate	4.5
Low	20	57
Medium	140	440
High	700	2960

Runtime & Regulation

High mode started out at what I estimate to be 700 lumens or so. It started thermal throttling before the 30 seconds mark which is surprising because the light barely feels warm in the hand at that point. It’s not a super hard stepdown like a hotrod though. It ran for about 190 minutes before low voltage stepdowns kicked in. After several of those stepdowns it continued to run until I ended the test at about 320 minutes. It probably would have run awhile longer at that low level.

Medium mode was quite stable and ran at an estimated 140 lumens for a solid 380 minutes before low voltage stepdowns kicked in. That sounds about right with a 3000mah Samsung 30Q and the 440ma current draw I measured at that brightness. It continued to run until it shut off at about 460 minutes. I didn’t test low mode because it should run for well over two days on a 30Q, and I’m sure moonlight mode would last for ages.

I did some rudimentary regulation testing by checking the relative maximum output at 4 different cell voltages. Regulation isn’t amazing but it’s not the worst I’ve seen. Here are the results.

Voltage	Relative Output
4.2	100%
3.7	100%
3.3	45%
3	25%

Emitter & Beamshots

I chose an SST-20 4000K 95CRI emitter for this build. This light is designed to be a “tactical” EDC light that doesn’t compromise on everyday usability and the SST-20 4000K is perfect. The color temp & tint are very nice, the CRI is great, and it’s pretty throwy too which I like in an EDC light. The intensity is also good for “tactical” situations where you might need to shine the light in someone’s eyes. There’s just the slightest bit of uneven-ness to the corona from the centering ring being slightly over-sized, but it’s very hard to tell even on a white wall. The orange peel reflector really does a fantastic job of smoothing out the beam. The HDR on my phone camera tried to add some faint rings in the photo below, but they aren’t there IRL. You can see the slightly uneven corona.

Emisar D4V2 SST-20 4000K Narrow Spot | Convoy M1 SST-20 4000K | Noctigon KR1 W1

It’s just a hint warmer than my D4V2 with SST-20 4000K’s & the narrow spot optic. The hotspot is noticeably wider than my Noctigon KR1 W1, which makes sense. The spill is narrower though which surprised me. This light has narrow enough hotspot that it throws well, but not so narrow that it’s a little hard to use up close like the KR1 W1. The transition from hotspot to spill is a lot smoother on the M1 thanks to the orange peel reflector. The KR1 has some flower pedaling.

These shots show off the difference in spill & hotspot between these lights. The corner of the white garages is about 100ft (30m) away. As you can see by the pale green electrical box (~65ft / 20m away), the spill is nice, bright, and usable on the M1 and KR1. For the D4V2, the spill isn’t quite as bright. It doesn’t really need spill since the hotspot is so wide though.

Here is a comparison of the hotspots between the three lights from 38ft (12m) away. This really shows off the hotspot & corona size difference between this M1 build and the Noctigon KR1 W1. You can also see that even with the Narrow Spot Optic, the D4V2 just floods the entire height of the building.

Batteries & Charging

This light runs on a single 18650 cell. I did all my testing with flat top, unprotected Samsung 30Q’s. The driver is advertised as “never leaving you without light” implying that there is no lvp (low voltage protection) but I observed otherwise. Once the cell reaches 3 volts it drops in brightness. That reduced load usually brings the voltage back up above 3V. It steps down another level every time the cell drops below 3V. If you turn the light back on to a higher mode, it will step down again with distinct steps so it’s impossible to miss.

There’s officially no LVP, but I observed that eventually the light drops to the moonlight levels that don’t work when cell voltage is low enough. When I stopped my medium runtime test, there was no light being emitted despite the switch being in the on position. The light would still turn on at a higher mode no problem, so technically you can reset it, but I’d call this behavior accidental low voltage protection.

When I stopped my medium runtime test once the light had shut off, I measured cell voltage at 2.98V.

There is no integrated charging on this light, which is a plus in my book. It keeps cost down and means there’s no silly rubber flap to deal with. Swapping cells is easy by removing the head.

I did find the battery tube to be a little roomy. There was a fair bit of cell rattle with my 30Q’s, so I cut some pieces of masking tape and lined the inside. Three layers snugly support the cell without making it difficult to remove.

Switch

The switch on this light is great! It took some fitting, but it was well worth it. The forward clicky switch from mountain electronics is so tactile and it’s just a joy to use. Double-tapping for turbo is a breeze. It’s got a nice, loud click but I don’t have to hear it every time I turn on the light since it’s a forward clicky. It’s totally silent until the click, and there’s plenty of travel between electrical contact and the click so I haven’t accidentally pushed too far and clicked it on. You can tell where electrical contact is made and you can tell where the click will be.

In order to make the switch fit, I had to do two things. First I had to cut the little rubber nub off of the inside of the switch boot. This was really easy since the boot can just be flipped inside out. My pocket knife sliced through the rubber just fine. The other change I had to make was to the retaining ring. There was originally a lip around the outside edge that made the total thickness of the retaining ring too thick. I filed this lip down flush with the rest of the retaining ring to make everything fit better. You could probably get away with not doing this if you aren’t using a Switchback, but the tailcap wouldn’t clamp down on the switchback properly without this modification. If it were on a 16mm PCB instead of a 17mm, the modification to the retaining ring wouldn’t be required. You could probably file down the edges of the PCB instead of modifying the retaining ring, now that I think about it. I know that’s necessary to fit it into some other lights like the S2+.

I wouldn’t mind seeing a beefier spring on this switch, but if current is an issue a spring bypass should work fine. The spring has plenty of give and it’s nice and long, so even with the added length of the switchback the cell doesn’t lose contact if the light is bumped.

Conclusion

What I like:

• The looks & the feel in hand
• The Beam
• The switchback is awesome, as always
• Forward clicky switch

What I don’t like/would like to see improved

• Unreliable moonlight modes
• Driver can’t deliver as much current as I’d like (without engaging FET)
• Incorrect voltage readout

The goal of this light was to be a “tactical” EDC light that doesn’t compromise on everyday usability and I think it doesn’t disappoint in that regard. In the two weeks I’ve carried it, it’s quickly become my favorite light of my collection, de-throning the venerable Emisar D4V2. The only thing I could see replacing this light would be a Convoy M21B which is virtually identical except it uses a 21700 cell. I’d put the same parts in it, assuming the Thyrm Switchback DF will fit (update: it won’t).

Thanks for reading