Sofirn C8F 21700 Teardown and Review

Yes. I did not know if I would succeed with the hot air swap. I might have accidently blown tiny resisters right off the board! :open_mouth: Luckily, everything went smoothly.

I had my air flow at the lowest setting and added flux around the edges. I tried 300*C, but it wasn’t enough. 340*C got the job done. I brought the temps up slowly so my old FET is probably still good. Once removed, I wicked all the old solder away and the pads looked fine. Added flux and put fresh leaded solder on the pads. Added a bit more flux and set the new FET into place. I heated everything up slowly then focused the heat on the FET. It dropped into place and I pressed down on it to squeeze out any excess solder. I’m glad to see that the hot air gun in my soldering station works so well.

Maybe use this hot plate might make it safer and easier?


https://www.aliexpress.com/item/UYUE-110-220-V-Mobilephone-Built-in-Pump-Vacuum-Metal-Body-Glass-LCD-Screen-Separator-Machine/32801227476.html

How has it worked for you?

I can probably get by with blowing hot air on the bottom of the mcpcb. I don’t see a need in buying yet another specialty device just for leds that I might do one per year.

I use small round elect, Skillet from caravan with thermostat.
using Laser Thermometer to check temp’s. (I had both)

Nice work Jason :+1: More instant Turbo? Are you still seeing a bit of climb?

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.