Sofirn C8F 21700 Teardown and Review

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JasonWW
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SKV89 wrote:
JasonWW wrote:

The Sofirn battery gained about 2 amps and 400 lumen. 3,450 lumen, wow!

The 30T battery gained about 1.5 amps and 300 lumen.

The 50E battery gained about 1.4 amps and 300 lumen.

The little Samsung 30Q gained about 1 amp and 300 lumen.

So some pretty nice gains just by swapping to 18ga wire. Beer

Very nice info. So the 30T measured 3,400 lumens, which is less than the Sofirn 4000mah because of bad connection? Also the performance of the Sofirn 4000mah is very impressive. Seems like a rewrapped Samsung 40T.


I would say the 30T and Sofirn 4000 are pretty much similar in this particular test. I think the emitters and circuit are starting to max out. We might see the 30T gain an advantage again if we swap out the skinny driver bypass wire with an 18ga. I’m guessing here.

If we go back to the skinnier stock led wire test, we see the 30T has a definite advantage with about 0.4A and 200 lumen more. So it is the better cell when it comes to high amp loads and having lower internal resistance. Dale has used a pair of 30T on a triple xhp70.2 light and they drew about 48A-50A. I don’t think the Sofirn 4000 would do as well in this extreme test.

Also, I did this last set of tests pretty fast and the light only cooled down for maybe 2 minutes between each pull. It’s not ideal, but still gives a pretty good idea of the differences.

We also know the Sofirn 4000 is not a 40T. It’s made in a different factory (in China) for the electric vehicle market. It’s definitely a good cell. Maybe it’s a Lishen LR2170SA 4000mah? The Liitokala 4000mah 21700 is a rewrapped Lishen and this cell performs really well also. I don’t know, but they do seem very similar.

JasonWW
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SKV89 wrote:
Besides the C8F, I haven’t compared my numbers with any of his. I guess the diffuser on the TA tube evens out the beam for more accurate result whereas other lumen measuring devices might favor concentrated beams.

Yes, very throwy lights do measure even higher with his tube. I think I found his tube sometimes measures between 8% to maybe 16% higher than mine on average.

He may know a few other tricks to boost output as well. Like using warm batteries fresh off the charger. I’ve heard warming up the batteries gives them some extra oomph. He might replace the lenses with UCP which have lower losses, etc… Dale just gets all the highest output. I can’t compete with him. He’s the king! Lol

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Didn’t know China makes batteries for electric vehicles too. Would love to see a HKJ comparison Sofirn or Lishen LR2170SA vs a 40T and VTC6A soon.

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JasonWW wrote:
Here’s an update. I swapped out the factory wires (I think 22ga) with some heavier 18ga. I ended up shortening them about an inch, but that’s barely long enough. I recommend 1/2” shorter at most.

Once I got a decent connection with the driver retaining ring, output jumped up quite a bit. Look at the bottom of the page. I was in a rush so I only did Turn On and 15 seconds for both tail amps and lumens with each battery.

The Sofirn battery gained about 2 amps and 400 lumen. 3,450 lumen, wow!

The 30T battery gained about 1.5 amps and 300 lumen.

The 50E battery gained about 1.4 amps and 300 lumen.

The little Samsung 30Q gained about 1 amp and 300 lumen.

So some pretty nice gains just by swapping to 18ga wire. Beer

Probably should send Sofirn this info so that they can improve the wire gauge being used and increase the lumens output to the correctly stated lumens (C8F 21700 stated to be 3500 lumens, and so far the stock form varies from around 2300-3000 lumens based on these user reports in the forums, which is way short of the “3500 lumens” claimed output.

JasonWW
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I mentioned that I sent Sofirn this info in post 56.

They probably should just reclassify the light as 3,000 lumen. That would be more accurate.

The only real change between the 18650 version and the 21700 version is the battery size. It doesn’t make sense that a battery change alone would give you an extra 1000 lumen. An increase of about 500 lumen is much more realistic.

I hope they change the wire size, then they could rate it above 3,000. A real hotrod then.

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I’ve been working on and off on trying to figure out how the switch light circuitry works, but so far I’m at a dead end. It’s certainly not a traditional switch light setup that uses two different color LEDs. On those you typically have one wire that acts as a common ground or common positive and then three more wires for the switch and two colored LEDs. The C8F has a switch, two colored LEDs and uses four wires, but the design is very different. Maybe someone here that knows more about electronic circuits can figure it out. Here is what I have so far.

A couple of the circuits.

Wire #3 does not go to ground to make the red led light up.

Both red leds are wired in parallel. Both green leds are wired in parallel.

Here is the basic led circuit minus the switch stuff and the duplicate leds. This is the most up to date.

If anyone can make sense of it, please let me know.

lohtse
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anyone if they will be doing the c8t in 21700??

Caving, Climbing, Mountaineering, Kayaking, Diving etc any time anywhere!!! If you in the UK let me know and lets Play!
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johnkey68
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Store Sofirn kindly sent me a driver for C8F 21700
In my opinion it is different from the original version.



prototype3a
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I’d kind of like to see a 26650 C8F or something even floodier.

SKV89
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Did you measure the output?

Sofirn Samsung is very kind. They had a brand new C8F 21700 shipped to me from Amazon for free. I was shocked to see the label titled to SKV89 and was wondering what the heck could be in the package. The output, unfortunately, measures the same as the output of the one I bought originally from Aliexpress and is also the same as the output after swapping in the free replacement driver into the Aliexpress C8F 21700.

Regardless, I sincerely appreciate Sofirn’s generosity and excellent customer service.

johnkey68 wrote:
Store Sofirn kindly sent me a driver for C8F 21700
In my opinion it is different from the original version.



!https://preview.ibb.co/cR7DLV/DSC-2777.jpg!

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prototype3a wrote:
I’d kind of like to see a 26650 C8F or something even floodier.

You should try the new Sofirn SP33 with xhp50.2. It has a little bit larger hotspot. Nice 26650 size. The boost driver kind of spoils me due to it’s consistent output and low heat production. It has replaced my C8F.
prototype3a
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I think I actually have two of those coming to give to the inlaws as a Christmas gift. I also got a single C8F to play with.

Funtastic
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Received my new order and it is disappointing to see no change in output. The plus side is the thermal sensor making it safer and more user friendly for my customers.

I get no higher than 2650 at 30 sec

It’s puzzling as to how they got 3500 lumens. Their ratings are usually not that far off. I see d_t_a mentions a wire gauge change boosts lumens a fare bit. I’m not going to bother as that would be a big hassle to perform on all of them

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The manual states it steps down at 50C but I just ran a test and it kept on Turbo until I had to turn it off from the heat. It was too hot to touch on the head and top of battery tube. My 30Q was very hot. It was maybe 65C and still no step down

What’s everyone else’s experience with this?

I was in ramping and in Turbo. This one might have a fault?

EDIT: just tried another C8F with the same result but measured the temp and it was still climbing at 56C with no step down. The whole light was around the same temp and battery at 45C. Why don’t they step down at the specified 50C?

EDIT 2: Ran another test on my lumen tube and let it run slightly longer this time. Turns out it steps down at 58C to 800ish lumens. It felt scary hot though….I think I may have peed a little Big Smile

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Funtastic wrote:
Received my new order and it is disappointing to see no change in output.

I get no higher than 2650 at 30 sec


Yeah, they should have stuck with the same rating as the 18650 version which was about 2570 lumen or so.

FET drivers are greatly effected by resistance in the circuit which includes the battery, driver pcb, the FET, the LED, etc… There is just some extra resistance somewhere that’s reducing the drivers full potential.

Still, I don’t mind 2600 lumen. It’s bright for such a small light, plus you can run it longer at that level compared to if it was 3500 lumen. It’s ehh, whatever. Having a nice user interface is more important to me. I find the new Sofirn SP33 to be better than the 21700 C8F.

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I should be receiving the SP33 later this week! looking forward to it.

It certainly is enough light for the C8F. The 18650 version at 3100+ lumens just got way too hot on Turbo for practical use. It’s quite nice having no step down timers as well.

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I am currently trying to get a 22mm TA driver working in my C8F host. I am trying to figure out with trial and error which two wires of those four let the momentary switch work. Can anyone help me to solve that problem or do I need a new switch? Maybe I already killed the switch lights Facepalm but they are not that important for me.

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JasonWW
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Skylight wrote:
I am currently trying to get a 22mm TA driver working in my C8F host. I am trying to figure out with trial and error which two wires of those four let the momentary switch work. Can anyone help me to solve that problem or do I need a new switch? Maybe I already killed the switch lights Facepalm but they are not that important for me.

You’re not going to be able to get the lights working on the switch unless you cut pcb traces.

As far as the two wires to operate the switch, see below.

The black wire goes to the driver ground.

The white wire goes to the driver switch positive.

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Thanks for telling me. I would have needed to try all combinations otherwise. Do you know where I would need to cut traces to get the switch leds working? In the mean time I will try to solder the black and white wires.

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Skylight wrote:
Thanks for telling me. I would have needed to try all combinations otherwise. Do you know where I would need to cut traces to get the switch leds working? In the mean time I will try to solder the black and white wires.

I show all the circuits a few posts above. You’ll need to replace the double leds with single units, cut a trace then solder a jumper wire – I think. I’ll have to look at it later tonight.
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I’m already happy if the switch works. I already killed the green leds. Maybe I could fit a Q8 switch inside. Thanks for the nice helpful circuit drawings.

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I managed to complete the TA driver with a working switch. But now there is another problem: Outside of the driver cavity the driver works perfectly when connecting a battery. But as soon as I screw it in with the retaining ring it stops working and shorts the battery! I have no idea where the unwanted contact is.

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contactcr
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if your batt + spring is compressing too much or sideways it can touch a 7135 leg on the back side of the driver. I suppose you could test with an 18650 and the spacer to see if the shorter battery helps.

JasonWW
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Skylight wrote:
I managed to complete the TA driver with a working switch. But now there is another problem: Outside of the driver cavity the driver works perfectly when connecting a battery. But as soon as I screw it in with the retaining ring it stops working and shorts the battery! I have no idea where the unwanted contact is.

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.
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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?).

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Marc E
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Funtastic wrote:
The manual states it steps down at 50C but I just ran a test and it kept on Turbo until I had to turn it off from the heat. It was too hot to touch on the head and top of battery tube. My 30Q was very hot. It was maybe 65C and still no step down

What’s everyone else’s experience with this?


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.
prototype3a
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All the LEDs in the C8F are just wired in parallel, right?

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prototype3a wrote:
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.
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Thank you contactcr and JasonWW for your help! Thumbs Up 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. Grad

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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.

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