BlueSwordM wrote:

It won’t probably thermal throttle on the 500 lumen mode, and it will step down on the timer, but you will be able to get the 500 lumen mode back up.

Is this about SP33 or C8F? If both can manage constant 500 lumen, then added max lumens on C8F feel tempting, even though I’d need to pay quite alot more for it than SP33 (damn taxes on 22€+ shipments)

The SP33. The C8F can’t actually manage more than 100 lumens of constant brightness, so the 500 lumen mode on the C8F will go down by quite a bit as the battery drains.

The SP31A would only be using Buck mode if 2 CR123A’s are installed. They have low capacity compared to a high capacity 18650 so using those half cell sized batteries would be sort of silly. Am I missing something?

No. The SP31A uses an XPL2, which has a very low forward voltage compared to the XPL, and especially XPL-HI.

On turbo at 1000 lumens, it’ll stay in regulation until the cell voltage reaches 3,7V using most buck drivers with a drop out voltage of 0,5V.

On the 350 lumen mode, it’ll basically stay in regulation down to 3,3V, where most of the useful energy of the cell would be used, about 2,5Ah out of a 30Q, so almost all of the capacity out of the cell before internal resistance goes up, so the 350 lumen mode will stay regulated up until the cell is almost empty.

That’s also the reason the XPL2 is such a monster: it can draw a ton of current from a cell since its forward voltage is very low.

Using a very low voltage LED like the XPL2, Nichia 219C 90CRI, LH351D 90CRI, and E21A array are probably the only LEDs in which using a buck driver is actually very useful with a single 18650.

Have used dozens of those emitters, haven’t noticed them having such a low Vf, probably because I don’t give em the chance…

Bottom line is:

The highest sustainable output plus the longest runtimes will always be with a bigger light. It can dissipate heat better and usually has bigger batteries.

Generally speaking, go with the biggest light you can.

So for those of you that are planning to buy a 21700 C8F host version and can’t figure out which driver to use. I can recommend Lexel’s narsilm driver. I had a 22mm driver that I grinded down until it fit. There’s plenty of room on the topside ring of the driver that it sits on the driver shelf without any of the driver components touching the shelf. On the bottomside of the driver, I added 3 solder blobs placed on the ring high enough that it just touches the retainer ring (I can post a picture later if people want to see it). Just remember to not put to much pressure when screwing in the driver retainer ring so that it cracks a 7135 chip (ask me how I know this).

Only problem with my light is that I accidentally ripped off one of the switch wires from the the soldering pad on the driver so now I need to try and fix it later. I emailed Lexel and he wrote me back how to get around it, so hopefully I can salvage the situation or if not I guess I’ll order another driver from Lexel.

The other problem I ran into was that I couldn’t figure out how to wire the stock switch to the driver. Luckily I had one of Lexel’s switch boards, it’s much easier to wire the switch when the solder pads are labeled. After putting the switchboard together, I realized that the leds weren’t bright enough for me (since the rubber boot is a dark color, anyone know if there are clear replacement boots that fit?). So I when I have more time I’ll go back adjust that as well.

I received mine, took nearly one month but Sofirn service was superb. Flashlight is a thing of beauty. Better than my former favorite, the original spec (3450 lumen) Jetbeam TH20. The 21700 battery combined with three deep-reflector well LED is so much better!

I had a chance to go Turbo with the EFEST from Battery Junction. “Overwhelming force” is the thought that describes it. I have used the Jetbeam TH20 a lot with fully charged Sony VTC5A and Sanyo UR18650NSX. This Sofirn C8F 21700 with the EFEST is remarkably brighter. My dark, cavernous kitchen is lit up entirely, and into the backyard. It feels on par with the old Thrunite soda can lights from the year 2014 in terms of shock and awe feeling. Very bright. Perfect for pest control. Wish I had this over the Jetbeam TH20 when I was pest controlling food moths. This is just plain brighter, for longer, and covers a greater area.

vinte77 wrote:

anyone know if there are clear replacement boots that fit?

Kaidomain carries a lot of boots.

vinte77 wrote:

So for those of you that are planning to buy a 21700 C8F host version and can’t figure out which driver to use.

Today answered :

Thank you friend
Yes, a driver for C8F-21700 is available, i will do a new link of it

Any news about the flat tail?…

I still haven’t got mine. It’s almost a month now. I hope it didn’t get lost. The last tracking date was Sept 2nd in China and then nothing.

Oh well, hopefully it will just show up. Lol

I used my 21700 C8 last night on my Thursday night walk, the Samsung LH351D in 5000K 80 CRI looked really good in the night and the power level was really good as well. Enjoyed it a lot, sure to be a favorite among my user group and will make it harder to decide which light to grab.

Has anyone tested the temperature at different brightness at room temperature?
I have a C8F 18650: in 1500Lm its temperature is less than 55C, at 800-1000Lm and turbo 2500Lm after 20 minutes at 58C, at 650LM in 25minutes 55C. It turns out the most effective mode of 1500Lm and 2500Lm.
And how does the C8F 21700 behave?

Does anyone know if Sofirn will have the new C8F hosts without branding on offer? I saw that other C8s are available on their store aliexpress page without engravings and that would make that host much more appealing

a few of us have already received the hosts and they did not have any branding on them. However, no promises in what you will receive.

Great news! Time to build my first torch then

Remember that you need a driver that takes an e-switch. The e-switch in the Sofirn C8 host is mounted on a board and held in with a threaded retaining ring, it’s all installed when you get it with the wires sitting loose in the head. But you need a 21mm driver that takes an e-switch. They provide the copper MCPCB that mates up to the reflector, you’ll need to reflow emitter onto it… XP footprint.

And yes, my host is unbranded.

Yes, I did gather all that information, reflowing emiters onto the MCPCB would defo be quite challenging so it might not be stupid to ask someone for help with this later.
May I ask what drivers did you get for this build?

I apologize. At full 18650 1500Lm almost does not differ from the turbo, heating more than 800-1000Lm.

I built an Anduril driver with an ATTiny85 MCU and FET+1 set up, used a 17mm driver board from Wight, the A17Hybrid-S, and adapted it up to the 21mm opening.

Just got an update from Amazon US..it says it will be here Thurday..YAY

Brainsick67 wrote:

Just got an update from Amazon US..it says it will be here Thurday..YAY

Being budget-minded, instead of purchasing a 3rd 21700 cell, I will use the 18650 I already have.

LEDtec wrote:

Yesterday I received my C8F 21700,
I measured only 2140 lumens, and only 6.07A at the tailcap.
Moreover when I step in turbo mode the brightness starts at about 1200 lumens and then slowly, in about 8/10 sec, it goes up to 2140 lumens, I do not think this is normal?

Maybe a stock of faulty drivers ??

But I bought it to tear it apart… so meh…Truly love the build quality, it is outstanding!

I got mine also..when u hit Turbo..it creeps up to turbo like the post above..im unsure the lumen measument.

Hmmmm..how do u check the amps?