Sofirn C8F 21700 Teardown and Review

Is the retaining ring touching any of the components on the driver? You may have to increase the diameter of the retaining ring so that it doesn’t touch any components.

I tested the driver with a 18650 battery holder holding one cable to the spring and the other to the outer ring. I didn’t compress the spring. The driver retaining ring is touching the plastic part of the 7135. Shouldn’t be a problem?! So far I didn’t screw the battery tube on with a battery because I fear it would explode then (maybe not but who knows?).

I have a Utorch C8F which seems to have a timed ramp down to medium after being on Turbo for 5 minutes (+ a few seconds). Didn’t see any sign of temperature control during this time.

All the LEDs in the C8F are just wired in parallel, right?

The main leds? Yeah, that’s why they run on a 3.6v battery with a FET driver.

Thank you contactcr and JasonWW for your help! :+1: I managed to complete the C8F successfully now apart from the lighted side switch. I resoldered the wires on the MCPCB and isolated the reflector with kapton tape. Lexel gave me this hint in the TA drivers thread, he said shorting wires are the only possible cause he could think about. It must have been the positive wire contacting the copper of the PCB or the reflector. After screwing everything together again it worked well. :student:

I forgot you had to unsolder the mcpcb wires for a driver swap. I thought yours were still stock. Oh well, glad you got it sorted.

LoL all of this current draw optimization treadmill is pretty crazy. I see the MOSFET used in the new 21700 C8F should provide some extra edge over the 18650 version, but it seems you do not get the expected results because of some “unaccounted” roadblock. At least on paper the newer PSMMN2R0-30YLE MOSFET is better than the AON6418 used in the 18650 C8F, but please note both MOSFETs are outside their optimal RDSon to VGS zone in the graphs, RDSon creeps much higher under ≈3.8V for both according to datasheets. Maybe going back to the AON6418 would “fix” this (= AON6418 “better” in practice)? Or using a MOSFET which actually works well with low VGS values.

I do not really care about flashlight drag racing. To me the actual performance of my flashlights is the one I can always count/rely on nearly irrespective of battery SoC or temperature.

Preheating batteries to attain higher current draw LoL!

Cheers :-)

I wish I understood more about the mosfet specifications, but I barely understand how they work. Lol

I’m not sure why you talk about preheating a battery to get better performance. I don’t think that was mentioned in this thread.

I agree that trying to get maximum amperage is not very practical. It just heats up the head and runs down the battery quicker.

I switched over to using the Sofirn SP33 v2. It’s got a nice regulated output. It doesn’t build up heat very fast and the battery lasts a longer time.

Yes it's been mentioned by… yourself!

Cheers ^:)

Oh yeah! I forgot. Lol

I recently ordered another Sofirn C8F-21700, and noticed that the tailspring is now not factory-bypassed (left), but instead uses a double-spring (right).

I think they now have the same tailspring as the Sofirn C8G (which also uses the double-spring). (I tested that the C8G and C8F-21700 are interchangeable)

Any idea if which one is better? Which can pass higher current?

I notice that Sofirn's factory bypass wires tends to get detached when using high-drain batteries (at least that's what happened on the Sofirn C8A and Sofirn C8F-18650 when I was testing Turbo mode for a bit longer time, and notice the factory spring-bypass wire on both sides got detached probably due to heat -- and I'm not good at soldering small parts)..

Properly done spring bypasses require wire coiling. Without it, chances for the wire to break are substantially higher. So either do a custom spring bypass, or use the double spring is my advice.

:-)

As Barkuti said. Properly done wire bypass gives higher current but double springs far more reliable. Even a properly done wire bypass can break over years.

User BlueSwordM can provide some nice high current springs. Check this thread: https://budgetlightforum.com/t/-/56987.

^:)

I hate putting springs on boards like this. They always seem to fall in that green solder mask area. Not even sure what the purpose of making it like that is

Hello everyone, where to buy a reflector “orange peel” for this flashlight? I really need this reflector! Thank you.

I’m not aware such a thing exists.

I’m looking at the C8F on the Sofirn site. They’re selling various tints.

I’m wondering if the issues described in this thread have been resolved by Sofirn during 2019. I’m looking at the 4,000k and thought they were only selling cold white when I looked last year. Or if this is a more recent version. I saw them selling prototype LT1’s on the same page, so I don’t think I can rely on this being current stock.

I’d be even more interested in the SP33 that one only comes in cold white and I don’t know how to do emitter swaps.

In ‘The general Sofirn development thread’ Barry from Sofirn wrote that they are now offering hosts and custom leds and tints in their flashlights.

The Sofirn C8F can be ordered with LH351D’s now.