Single LED 21700

The question will be if you want a specific CCT/CRI.

At 3V, any of the larger die emitters (SST-40, XHP 50.2 3V) are going to have limited CCT options, namely +5000K and poor CRI. The largest selection of emitters and drivers will be a 3V, smaller die (XP size, or 3535), paired with an appropriate driver.

At 6V your options are much better, but you’ll need to find a boost driver. H1-A is a cheap, readily available option, the two drawbacks are limited modes (simple 4-mode) and recently it looks like they’ve downgraded some of the components for it to be less efficient.

12V (XHP-35 HI) is really more of a pain than it’s worth IMO.

Pre-made SST-40 S21-A’s are available at the Convoy store, just plug in a battery and go

Not in my experience, the drivers can have up to 5 modes + moonlight (with a choice of 3 moonlight levels), max can be switched between constant current and direct drive, max constant current mode is adjustable and the modes will alter as percentage of the max current chosen, and you can choose between 4 drivers which deliver max current between 2-3A, 4-8A, 7-9A and 8-12A.
Sooo, what did you mean by a very limited range of current?

In response to your clean, white light requirement, i’ve not seen one in action myself but the Luxeon V is meant to have minimal tint shift across the beam, the XHP50.2 will be a bit multi-coloured as it transitions from hot-spot to spill. The SST-40’s not too bad though.

I guess I should have clarified a little better :slight_smile:
Meant from Low Power to Medium to High to Turbo Mode power levels. So long as I get a decent sized, wide hot spot, or none at all if a dedicated flooder, I’ll be happy with it.
My steadfast requirement is that this thing needs to be pocketable without it being overly huge.

Was very tempted with the Convoy SST40 prebuilt light, but the review on it said that it heats up so fast that as soon as ya flip on turbo, it starts stepping down.
So right now, thinking about the LED4Power 6A board with the remote FET and XHP50.2-3V.

Convoy L21a with XHP35 hi

Coolness :slight_smile: The output would put me on the lower end of my target, but this would be more ideal.
But the problem is the driver, aside from the GXB172, what would you suggest for this particular LED?

I don’t know what you mean, it’s stock 12V 2,3A which is the sweet spot for XHP35

See TA’s test here

Here’s a link to the light

Wellp, that’s normally what you get when the light’s small enough to be pocketable. Not much thermal mass to soak up heat before everything else gets hot, few if any cooling fins to help dissipate heat, etc.

Yeeeeeap. Nature of the Beast.
But the SST40 is known to not be the most thermally friendly if memory serves.


And don’t be tooooo disappointed if your first 20 or 30 don’t give you “exactly”,
what you wanting .

There’s LOTSA blokes on here been looking and experimenting for yrs.
And still looking. Chuckle.

Enjoy the life mate. it’s very diverse. and often frustrating.

XHP 50B 3V is only available in cool white, which is a huge factor in deciding.

The 5000K SST-40 beamshots I have seen look very nice. Throwier to get a bit more range, less tint shift, neutral temp and just a slight loss in output vs XHP 50. Either emitter will get a light HOT at max output and step down quickly anyway.

Unless I’m completely misinterpreting what their product page says…

that’s only a max range of 4A or less depending on which mode it is set to. So you get moonlight, whatever small amperage range, and optionally a direct-drive mode if you install the external FET. Am I wrong in understanding it that way? That seems far more restrictive vs a PWM’ed FET+7135 driver or similar option with output ranging from moonlight to direct-drive and including everything in between.

I’ll be honest and say I’ve never actually used the LD-4x, but from the datasheet, how I read it is that’s the setting for MAX amps. The mode mode groups then give you the tiers and are a percentage of that MAX. For example, if you set it to 3A, you can have up to a 5 mode group, and it’ll be a percentage of that 3A.

Alternatively, the datasheet says you can uncap it all and just go direct drive for the uppermost level as well.

That’s how I read it

I don’t think that’s the case because for each max amperage setting they also list an associated “down to” minimum current. All the reviews I’ve seen of their drivers explain it as working that way as well.

Ooooh! I know that feeling all to well! :slight_smile:
Since this is going to be my first actual build, I know that I will at least learn something from this.
’Least till I get the itch to do something crazier later, like the GXP172, XHP70.2 in an M3 host or something hehe

Max is maximum regulated current. It can be set to anything between 4-6A (in case of 4-6A driver). Number of modes can be configured, each is the percentage of max current. E.g. one of modes will be 30% of 4A or 30% of 4.5A or whatever configured. Furthermore the highest mode can be direct drive, but each of lower modes is still the percentage of the maximum configured current (i.e. 30% of 4.5A in my example)

Then what is the “down to” current they list for each amperage setting?

Okay then!
Thanks to all the input, I think I finally nailed down what I’d like for my first build in the Convoy S21 Host:
XHP50.2 6V 6500K
Kaidomain H-1A 6V Boost Driver

Not exactly what I would hope for initially, but this is a start! Ya never know that I could be happy with this :slight_smile:

Soon as I get off my ass to go through the BoM of the GB202 and the Switch assembly, I can work with my boss on putting together kits at I hope a reasonable price.
THAT would be my ideal toy to play around with hehe :smiley:

Thanks again guys!

(FYI, I’m a Senior Supervisory Tech at a Prototype SMT Shop with access to all sorts of goodies for low volume production :wink: )

FYI, if you want to spice up the build a little bit, you can try to overclock the H1-A

Neat! Something to tinker with later!
Thanks man!

Finally got all the parts in from Convoy and KaiDomain.
To say that I am in love with Simon’s S21A is putting it mildly!
Only a little thicker than my 18650 based Sofirn SP31.V2, and shorter in length!
Weight, only a little heavier, enough that it is almost negligible in difference. The XHP50.2-J4 fits like a glove, heats up on Turbo fairly quickly, doesn’t step down quickly as I have seen already, probably thanks to the IC Diamond Thermal Compound that I used.

Yeap… I’m Happy :wink:

Now if Simon would make a 20mm 6V Boost driver, I can get everything from the same source lol