Sofirn C8F 21700 Teardown and Review

What about stock, with no alterations? Are you seeing a bump in output?

Turn On - 3290
30 sec - 3070

Okay, I suspect that they improved the driver contact and got the retaining ring to clamp it down tighter.

3370 at 30 sec with the Sofirn 21700

Wanting to add that many have previously said Sofirn were using 40T’s but this isn’t the case. I ran tests on my CBA and the 40T is much much better

what do you mean by “blue’s spring”?

BlueSwordM sells his custom high current springs

ahh, i see. Did your c8f already have the double tail spring before or was it the single spring?

Dual tail stock I think it was the old 18650 c8f that had two single bypassed springs

So I just received my Sofirn C8F bought from Sofirn’s AliExpress store on 01\06\2020. The tail cap has the dual springs, but on a freshly charged LG M50T 21700 cell, I’m reading about 2300 lumen on my Texas Ace calibrated lumen tube. One of the holes in the retaining ring looks damaged and has a gash through the ring. Anodization looks like one small area has a rub mark. Will be contacting them. Will be trying a 30T cell on it to see if it’s the batteries internal resistance. Not happy about the retaining ring looking damaged, or the output. Does anyone know if the brass retaining ring from a Convoy can be used in place if the soft aluminum? Hopefully I didn’t get one with an old driver. Will be contacting Sofirn to hopefully get this resolved.

The old driver was still better than the numbers you’re seeing.

Make sure you clean all the contact areas and that the retaining ring is tight. If I loosen mine or cut the spring bypass I get approx 2000. Try redoing the spring bypass as I always get less with the factory job.

Thanks Funtastic,

Yeah I’m wondering if I do anything to it if they will honor warranty? :). I’ll try tightening the retaining ring, although one of the holes is damaged so not sure how tight I can get it. The bypass can be redone too. As long as the driver is correct the rest can be corrected (I hope)

The M50T has only a 7.3A rating so that looks to be the issue

When I first tested my Samsung 50E I only got 2200lm. After fiddling with the driver retaining ring I got 2700lm. A 30T squeezed out a few more at 3100lm. So the M50T is not that big an issue.

It’s just odd since my new lot are much better.

I’ve still got the old version if you want pics of both drivers

What lot are you refering to?

I never felt it was a driver issue, it seems to be a contact issue around the driver retaining ring.

I have one C8F from a previous batch that achieves 2700 and my new batch that gets 3070. With Blue’s spring and bypassed tail spring 3570 at 30 sec.

Something has changed, not sure what. My old C8F’s retaining ring is very tight and can’t get any movement of the driver whatsoever.

Notice how my retaining ring is a bit messed up? One hole drilled through side wall and the other is very close.

- Driver retaining ring

- Scuff off of anodizing underneath the “hot” label.

I think at a minimum I would want to get a new retaining ring. The packaging and all other accessories looked new. But I’m wondering if this was a refurb of the original batch to replace the driver? Not sure. But none of my Convoys came like this. I’ll try again with my 30T cell fully charged tomorrow as far as the output is concerned.

Nothing off looking though. I’m a dealer in New Zealand and quite often I get scratches and off centered holes in retaining rings on Sofirn lights. Sofirn used to apply black repair stuff on scratches in hopes of not noticing it. I had heaps on the old 18650 C8F’s until I complained and not long after I stopped seeing it

Sofirn offer excellent lights for the price, if you want everything spot on then look elsewhere

You could message Sofirn about the scratch and see if they’ll give a small refund

The question, is the ring tight against the driver or tight against the threads?

I think the threads bottom out right as the driver just starts to get squeezed. This prevents the driver from being squeezed hard like in a normal flashlight. IDK, this slight tolerance issue might be why some lights draw more amps than others and why the amp draw can vary when fiddling with the retaining ring (at least in my case).

I think YogibearAl should try loosening the ring and cleaning the edge of the driver on both sides, clean the ring and the flashlight head where the driver presses against, then tighten it up and see if the output increases.

His ring looks perfectly functional. Someone used pliers and squeezed too tight and that caused those gouges. No big deal, though.

Side note-

Anyone that would ask for a small refund because their light has a scratch or imperfection on it is a whiney little baby - in my opinion. It’s gonna get damaged the first time you drop it, so what’s the difference? SMH

Hmm, if it’s for personal use then yes, I wouldn’t bother, not for Sofirn prices. When selling them and I get some damaged ones I’d ask for replacements or a discount. I don’t get much cheaper pricing than everyone else. I do get wholesale pricing but Sofirn is barely making much so the difference isn’t much. Glad I don’t live in the US as I doubt I could resell and compete with Amazon. No Amazon in NZ yet and the Aus one doesn’t ship here