Sofirn C8F host. 21700 C8F Available

Thanks for the reply.

That’s good to know - I do actually have one of them on the way.

I also have the dedicated 18650 version (along with several other Sofirn lights) and that works fine so looking forward to the new arrival :slight_smile:

Thanks again,

Moley

You can buy it with a battery and charger for only $6 more.

Plus you’ll get 33% more run time from a 4000mah battery compared to a 3000mah.

In theory, Jason, that run time thing stands correct. BUT, the 21700 tends to allow higher currents to flow so the capacity gain may or may not actually net longer run times. :wink: IF you use a regulated driver that shares the same current in a light that uses both cells, then yes the 4000mAh will have longer run time. But then, is the Sofirn triple current regulated?

Hi again,

Well I now have my light and can confirm that Sony VTC6 18650 does work in the light.

However, I have a couple of issues with the light.

When I compare the “Turbo” light output of my C8F 18650 to my new C8F 21700 the C8F 21700 is significantly less.

According to my light meter my C8F 18650 gets a score of around 275-280 yet my new C8F 21700 only gets a score of around 235-240.

Also, I am having issues with getting the groups to switch; on a few occassions the light just gets “stuck” and doesn’t respond to the side switch and I have to remove the cell from the light - almost like having to “reboot” the light and then it seems OK for a while until it gets “stuck” again.

If anyone has any ideas or advice that would be great.

All the best,

Moley

Your normal light accepts the 18650 with a higher level of compression on the springs, the new one is barely making contact. Hence a lot of difference in output.

Not sure about the switching action, can you check that the retaining rings on the driver and switch board are snug?

The top of the ramp should only be about 1800 lumens. You need to double click to go to 3000 lumens Turbo.

It’s also possible that you may have locked out the light when you were trying to switch modes. Actually, I’m not sure it has an electronic lockout.

Got hold of a Sofirn C8F 21700.

The manual’s explanation for the UI seems to be a bit lacking, or fails to explain too well.

From how I understand how it works:

There are 4 mode groups for selection:

  • Group 1 has only 1 selectable mode
  • Group 2 has 3 selectable modes
  • Group 3 has 4 selectable modes
  • Group 4 is ramping mode

- now for Groups 1 to 3, aside from the selectable modes in that group, a double-click will go to Turbo mode,

- now (for Groups 1 to 3) to go to Moon mode, hold the side switch until the flashlight turns Off (“standby” mode), now hold down the side switch longer and it will turn on in Moon mode

  • another observation (for Groups 1 to 3), when going to Turbo mode, there seems to be a short ramping effect (it doesn’t instantaneously go to Turbo, but rather takes maybe 1 second to ramp brightness from High to Turbo mode)

- note that Group 1 has only 1 mode, so clicking the side switch will not seem to do anything since it has only 1 mode (double-clicking will go to Turbo mode though)

Here’s Zozzv6’s earlier post on the UI.

Ramp top is not adjustable. 1800 lumen is safe and sustainable output in this light with some warming. Turbo is I think 3000 lumen will be in factory data but they measured 3500 on a prototype. Better than tell more and get less. Visually to the eye it is no t a huge jump from 1800 to 3000.
If they use this firmware in the SP70 I think there will be ramp top at about 4000 lumens and turbo about 6-7000. My XHP70.2 MF02 with Andúril is setted up ramp top at 4000 and turbo at 8-9000 depends on battery level and type.

Here is the complete menu:
4 mode Groups:
Group 1: 500lm
Group 2: 100lm—700lm—1800lm
Group 3: 10lm—100lm—500lm—1800lm
Group 4: Ramping from 1lm—-3500lm
In any mode, including OFF, hold 1 second to go to Moonlight
In any mode, Double-click to go to Turbo 3500lm, one click to go to the previous mod

Group 1/ Group 2/ Group 3:
Short click the side switch to cycle through modes: Eco→ Low → Mid→ High→ Eco→ Low→etc.
Press the side switch for 0.5 seconds to enter Standby (main led is off).
4 Four fast clicks convert from one group to the other, 2 blinks confirm the change.
Group 4: Ramping
Press and hold side switch to ramp up or down. Ramping changes direction when press button again within 1.5 seconds, same direction when ramping again after 1.5 seconds. The light blinks when it reaches Moonlight or Turbo. When the light is on, click to Standby.
No matter in which group:
Hold and press the side switch for 1 second to enter Moonlight from Standby, one click returns to Standby.
Double clicks to activate Turbo mode from On / Standby, one click returns to the last brightness used or Standby.
Triple clicks to activate Strobe mode from On / Standby, one click returns to the last brightness used or Standby.

Memory Function: The last brightness used can be memorized when convert from Group to Group. When it goes back to the group, it starts from the remembered brightness level.

OFF
Press and hold the side switch for 0.5 seconds to enter Standby (except in Ramping Mode).
Click the tail switch to Cut Off. Please click both tail switch and the side switch to turn on if the light was in Standby last time.

Advanced Temperature Regulation (ATR) technology:
If the head temperature reaches 50 ℃ (122 °F), the flashlight will automatically throttle down to lower mode to avoid overheating

ZozzV6 posted contradicting information about this because he also posted this:

So which one is correct?

I guess we will find out! Lol

I don’t have my light yet so I haven’t been able to run any tests on it and verify the UI.

Hi and thanks for taking the time to reply everybody.

@DB Custom - the light has spring bypasses at the head and tail cap so would the battery length difference (ie spring compression) be that much of a concern re the loss of output?

I have been fiddling with the interface and am still having issues with it getting stuck. I will persevere as it seems like a really nice light outwardly.

Thanks again, everyone.

Moley

Yes. Battery compression strength is extremely important, especially in regards to springs.

Low compression force by the battery in the spring can result in very high contact resistance, especially if the spring wire isn’t thick(0,8mm in this case) and if it’s made of a hard material, like steel, although a gold coating helps quite a bit since it’s soft, but the problem still remains.

That means two things to fix it in the Sofirn C8F for complete 18650 compatibility:

1. Making the springs longer and thicker to lower contact resistance significantly without changing the material.

2. Solder a small 2mm thick brass button on top of the springs. You will get maximum compression, therefore lowest contact resistance possible if you use it with an 18650. It would work with a 21700, granting you maximum performance possible by making the spring fully compressed, but you would probably sacrifice protected 21700 compatibility.

I make it 3500 lumens in comparison to other flashlights off a ceiling bounce test.

The confusion was does it require double click to turbo to get 3500lm or can you ramp all the way to 100% turbo

Just to be clear, I wasn’t questioning the max lumen output of this light. I was asking whether it can reach its max output in ramping mode, or if ramping mode is limited to some lower output. Some statements said ramping is limited to 1800 lumen then you have to press something to kick it up to max, while others said ramping goes all the way to 3500 lm.

That was the top of the ramping.

I’m still not clear. Are you saying the top of the ramp is the same as turbo? It does not stop short?

Yes the top of the ramping is around 3500 lumens in comparison to other flashlights with that output.

Pretty sure the eye can’t compare 3500 lumens of light between different flashlights. You need a light box. The eye can easily misread hundreds of lumens, even a thousand. A slight difference in the beam profile or the tint of the output, the eye reads it differently.

The light box shows even small differences, whether or not the light box is 100% accurate it IS accurate at showing differences between lights or modifications. And that’s why we as individuals have light boxes, to show a gain or a loss when we are modding lights.

It was Moleyman69 that said his new 21700 light seemed weaker than his older 18650 version. I was wanting him to try double clicking to see if it improved.

I imagine we will get some good tests in the next week as more lights get delivered.