Sofirn C8F host. 21700 C8F Available

@SKV89, I have the feeling the spring bypasses are done with thinner wire, and aren’t done as well.

That could be the culprit, along with perhaps lower spring compression force resulting in much higher contact resistance. There could be many reasons for this.

There may be too much resistance in the new tail switch they added. Try measuring the output with the tail cap off and a thick wire across the battery and battery tube. See if the output jumps up.

There’s not much that has changed between the old c8f and the new one. The driver is different but it’s still FET driven. I assume they are using a good FET, maybe not. The tail cap and switch assembly is new as well.

Or try it with the same 18650 as the 18650 version.

Oh I had not thought about the tailswitch.

I really wish there was a regular tailcap without a switch, or a way to mod it.

Maybe it could have something to do with the spring bypass wires then.

Unfortunately, the spring bypass wire on my C8F 18650 broke, and I’m not sure I can solder that thing back (will need to buy a new thicker wire, but my problem is my soldering iron probably isn’t sharp enough to solder inside that small space.) Similarly, my SP32Av1 spring-bypass wire also disconnected (it was drawing upwards of 8 amps when I tested [using UT210E] the tailcap current back when the wire was intact). The C8F 18650 was drawing more than 10 amps tailcap current on Turbo when the bypass wire was intact (and now with the broken wire, it registers a bit less than 8 amps now). The tailcap current on my C8F 21700 measures around 8amps only, and as far as I can determine, its spring-bypass wire is still intact (not broken).

BTW, what kind of soldering iron or tip do I need to do spring-bypass wires on enclosed spaces like on the SP32Av1 or C8F-18650? I’d like to get them back to full throttle…

If the tail switch is problematic, it’s easily bypassed.

@JasonWW, thanks.

@SKV89, just bypass the tailswitch first. You will lose tailswitch functionality, but lower resistance by a lot.

No, what I’m saying is bypass the tail cap (not the switch) and see if that fixes the issue. If the lumens jump up then there is something about the tailcap reducing output. We then need to look at the spring, the switch, the retaining ring and the threads.

If the output does not jump up, then we know the tailcap is fine. We look elsewhere. Like at the driver, it’s retaining ring, etc…

I just replaced bypasses on my C8F driver and C8A driver and tailcap.

d_t_a, I don’t know about other people, but I don’t try adding or fixing bypasses in place. I take the tail cap apart. Next, I either remove (desolder) the switch, or protect it from heat by clipping aluminum heat-sink clips on the leads. Then, I desolder the tail spring, add the bypass and then reverse the process. I use a fat (~3mm) tip for the whole thing.

Thanks for explaning the process. So it’s really more complicated to do properly. Likely beyond my skills and my simple equipment…
I wish that Sofirn would have use a thicker wire for their bypasses and solder more properly from the factory… Should likely send them a friendly ‘complaint’ about this issue. Since it happened on both my SP32A and C8F (the tail-portion bypass got cut, likely due to inability to handle that much current on Turbo mode?)

I’m glad my light meter wasnt imagining things then re my 18650 version being brighter than my 21700 version.

If the Sofirn 21700 cells that I ordered additionally do not help the situation I will definitely be in touch with Sofirn for a friendly word especially as I am still having crashing issues (although it hasn’t been as bad the last few days) as I bought the 21700 version of this light plus 2 21700 cells as it was supposedly rated with a much higher output :frowning:

All the best

Moley

Let some more people get it so we can figure out the problem. It might be a simple fix.

I think someone needs to try doing as JasonWW suggests and remove tail cap and just firmly press a stiff wire to negative battery and the non anodized end of tail thread.

If that doesn’t show any difference then I guess checking/comparing driver wires (diameter/length) and components (FET) would be the next step. I only ordered hosts which haven’t arrived yet so I wont be any help.

Would a metal paper clip suffice?

a scrap of copper wiring would probably be best. like the stuff you find as a “ground wire” in a light fixture or scraps trimmed from household electrical wires

Or a copper coin. :wink:

Silver dollar!

Might be difficult to angle the larger coin into the battery tube to bridge the cell to the edge of the tube. :wink:

@contactr, never use a paperclip.

Trust me. You do not want molten steel on your hands.

Woohoo! My 21700 C8 host made it to the US! It’s in customs at LA, maybe another week or less…