Sofirn C8F 21700 Teardown and Review

I’m looking at it very carefully right now. If I set the brightness level a little below Turbo and then double click, it looks like the output drops a little bit and then it ramps up to the Turbo level. Very strange.

From a lower level, like 500 lumen, it seems to do a big jump in brightness then a little ramp up to full brightness.

It’s not too bothersome and better than before.

Now that Lexel is using Anduril, I may see about getting a new driver from him. I mainly want to try out that UI, but this stock driver seems to be fine for normal use.

Lexel had to order some boards special for the C8F 21700 due to this size and retaining ring. When my Mtn one gets in i’ll let you know how it works out. Only FET+1 though. I only ordered hosts though so my LEDs will probably be LH351D or something I have sitting around.

If you want to use lower temps when you do delicate reflows you should use leaded solder. 63/37 will flow much easier

That is all I use.

I see where I said the wrong thing earlier. I always try to get the lead free solder off the boards and replace it with the good leaded type. :+1:

I bought it but haven’t even opened it. Don’t have space on my desk for another flashlight related item. I prefer just buying the emitter already soldered onto the mcpcb from Clemence and Kaidomain. Much easier.

How many lumens do you think a Skyray King would output?

I had a customer who purchased a C8F XPL 18650 version and he already had a Skyray claiming 2000 lumens with 3x XML’s. He got angry saying I was selling falsely rated lights and his Skyray was much brighter because it threw further. I measured the C8F to be 2700 lumens.

Ended up saying that the different reflector on the Skyray could be making it seem brighter when it’s actually not. What do you guys think? Would like to get the facts in case I come across another unhappy customer.

Love now having the TA Lumen Tube to see that the Sofirn rating was accurate.

He may have been refering to the lux as brighter and not lumens. The SRK should have a smaller hotspot due to its bigger reflector so it might be more intense and throw further. The C8F puts out a larger diameter hotspot. Meaning it’s higher lumens is spread out over a wider area so it doesn’t look as intense.

Lumens is about total light output.

Very helpful explanation. Thank you

Dont know about the skyray king bit my c8f 18650 I measured 3,155 lumens running on fresh vtc5d batteries and cleaned contacts. My 700 lumen Skylumen Delta throws several times farther than my C8F. Your customer is confused between lumens and throw. You shoukd tell him to ask on BLF.

Is lux the intensity of the hotspot/place of the beam being measured?

Okay, I always thought lux = lumens when calculated correctly.

Lux and lumens are completely different.

Lumens is the total amount of light regardless of beam shape.

Lux is the highest intensity at any one point in the beam and is only useful to determine how far the beam will travel.

You could have a 200 lumen light that was floody and only measure 80 meters or you could focus it really tightly and make it go 800 meters.

if it was XML it’s just as likely he perceived it as more floody and looks more impressive at short distances or indoors. Either way it’s perceived brightness. You wont be able to really notice much difference between 2000 and 2700 except for the throw/beam shape.

On the “bright” side now he has a light suited for more flood and more throw, whichever they may be!

I just sent him the Sofirn Q8 so I’m sure that’ll impress him at 5000 lumens with spring bypasses.

Thank you for both of your input answering my questions

I just tested my new batteries in the C8F (has new MOSFET and stock led wires). I measured both lumens (TA Lumen Tube calibrated with Maukka’s light) and tail amps (using UNI-T UT210E clamp meter and heavy wire) with the Samsung 30T, 50E and Sofirn 4000mah 21700.

Something funny happened as all my first round results were down in power by about 500 lumen and two amps (left side of chart). I checked the driver components and saw no issues, but around the driver edge and driver shelf there seemed to be some dirt or maybe flux build up. I cleaned it all up with a q-tip and alcohol then reassembled. This fixed it. So new readings are on the right hand side. I did not recharge the batteries between the first two 30 second pulls and the second two 30 second pulls. I took Turn On measurements as well as 20 seconds and 30 seconds to give an idea of how output was dropping.

All 3 cells did very well. I think the 30T did not have as much voltage sag which is why it had slightly higher lumens while drawing the same amps as the Sofirn battery. It goes to show how good the Sofirn battery is.

Since I like this light so much, I may swap in a Lexel driver in order to get that instant jump to Turbo (no more ramping up in output) and to know the battery voltage better. The stock driver does not start showing red until 3.0 volts.

Oh yeah, I charged each cell on my Miboxer C4-12 and tried to get a rough idea of their Internal Resistance. This charger is known for reading IR a bit high, but the results seemed fine.

Did you buy another one or did you swap in the revised driver they sent you? Thanks for the very useful data!

I only have the one light with the original driver. A few posts back I showed that I swapped the FET out for one with lower resistance.

I read that Sofirn had confirmed it was the FET causing the reduced lumens, this can’t be the only cause looking at your results

I am not ragging on this new version but I just have 2 questions;
So only after these mods of replacing the FET and beefing up connections is this flashlight just now getting to the output I already have out of the box with the 18650 version when used with a good cell?

Just a newfangled 21700 battery capability.
Where’s the love?

Will wait for the factory BLF approved/vetted Hotrodded version.

The FET they used in the early drivers did have a little more resistance in it which reduced output. The details are in post #17

I actually don’t know what a triple xpl can do amperage wise. Right now each emitter is doing about 3.2A and about 1000 lumen.

Should we be expecting 15A and 4000 lumen?

Is there too much resistance in the led wires?

A completely new driver might tell us if there is something in the Sofirn driver that is creating a bottle neck.

Frankly, I was okay with the stock driver that only drew 7.25A and 2600 lumen. I tend to set it at about 500 lumen for walking around and do the occasional blast of turbo. It’s a big jump in output and it doesn’t get too hot or run the battery down too fast. It is a good general purpose light.

Using the 30T and 4000mah battery gets the light hot so fast it’s not that practical anymore. If I put a Lexel driver in it and got even more output, I’d probably remove the spring bypasses to try and reduce output on turbo to make the light practical again.

I know, it’s not the BLF way to reduce output, but I use this light at work where it needs to be a bit more practical.

The latest versions already have the updated FET so you don’t need to do anything.

What do you mean by beefing up connections? Both springs are factory bypassed. There is nothing to do there either.

Do you mean replacing the led wires with bigger ones? How big are the wires in the 18650 version? Bigger or the same? I don’t know.

How many amps does the 18650 version pull? I don’t have one so I don’t know.

I looked up reviews for the 18650 xpl version to find amp draws. (This is usually more accurate than lumens)

Bilakos10 measured 8.33A with a Samsung 25R cell, but that is not a very good battery.

Robo819 measured 8.4A with the Sofirn 18650 and 8.9 with an LG HE4 cell.

ImA4Wheelr measured 8.8A with the Sofirn 18650.

Barkuti measured 9.7A with a Samsung 30Q. He used a shunt as apposed to a clamp meter.

DB Custom drew 13.57 amps with a very high drain VTC5A 2600mah and with slightly lesser batteries, like a 30Q, he got between 10A and 11A. This was with 18ga led wires and an upgraded MOSFET though. So it doesn’t really count as stock.

Since the 18650 version is supposed to be about 2500 lumen and the 21700 version is supposed to be 3500 lumen I’m guessing there is some kind of bottleneck with this 21700 driver. The 21700 light should probably be drawing at least 12A to 13A stock to get 3500 lumen. Sofirn may have over rated this 21700 version. It might be a true 3000 lumen light.