LED suggestions?

Flashlight Modding and DIY Parts
1

I have a Sofirn SC18 and it uses an SST40 that I sliced.
I wanna do an emitter swap on it for more brightness.

So is there an led that takes almost the same amount of current as an SST40 but is brighter?

2

3V XHP50.3 HI would do.

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3

What’s it’s current rating?

4

The 6v XHP50.3 HI will be fine to 8A, so the 3v version is fine to 16A or more. Convoy sells them on aliexpress, they can do over 3000lm

It will be able to use more power than the stock battery can provide, so I recommend going to a Samsung 30Q (or another 3Ah 15-20A cell)

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5

Won’t the driver limit the current to around 5-6A?

6

AFAIK the SC18 is direct-drive (FET) and might also have a current regulator like a 7135 chip for low modes.

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7

Thanks!

So I currently have two choices
A 3V Cree XHP50.2 HD and an XHP50.3 HI

Which ones brighter?

8

3V XHP50.2 or SFH55 will be brighter. If it is a direct drive FET driver, an SFT40 may also be brighter with a higher CDR battery than the stock one, but will likely put out slightly less light using the lower-drain stock battery.

50.2. Also, the 3V XHP50.3HI is very new, be sure you don’t have the 6V/12V version instead.

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9

If you’re lumen hunting then you might end up disappointed. A difference of say 2,000 and 2,500 lumens won’t be very noticeable to the eye.

One strategy is to go for a throwier emitter. Depending on what you’re shining it at, you’ll generally put more focused light on target and it will appear brighter. I’d say an SFT40 5000K. That one has better tint than the 6500K and most of the output (I often prefer light quality over quantity).

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10

The XHP50.2 is slightly brighter but has a higher Vf (meaning it will lose brightness quickly as the battery drains)

It also has a huge dome, which might not fit inside the optic of the SC18.

The XHP50.3HI will be close, but the beam profile will be more intense, which feels brighter.

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11

Will choose 50.3 HI

Thank you!

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12

Make sure you get the 3v version, like @wolfgirl42 said. The 6v/12v won’t work with your SC18.

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13

Here is a link to it, on Convoy’s aliexpress store. That way, you can be 100% sure it is the 3v version. I recommend getting more than you need, as the silicone is fragile.

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14

Just an emitter swap will likely do nothing, as changing nothing else would only gain if more efficient and/or have a lower Vf.

You want more lumens or more throw?

15

More lumens

I have decided on a Cree 3V XHP50.3 HI

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16

The increase in lumen output with the XHP50.3 HI might be limited by the driver wires and the springs. I just checked/looked at the driver wires in my SC18 and they seem very thin! (Max 24 AWG, but they actually look even thinner.)

The single spring in the tailcap might not be a huge bottleneck (it looks somewhat ‘beefy’), but when I look at the spring at the driver side, it looks very thin too.

The driver might be a pain in the *ss to get out, due to the design of the SC18, but it might be worth also putting in the time and effort to solder in thicker driver wires and do a spring-bypass, to be sure to get the most out of the XHP50.3 HI.

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17

The whole assembly with driver is press fitted. I once took one apart. Didn’t bother to put it back together though.

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18

Good to know, thanks!

I think reassembling might be more difficult, in getting the driver wires through the holes of the ‘shelve’, when pressing the driver back in. Easiest way might be making the driver wires “extremely long” and then trying to ‘manouvre’ the wires through the hole first and then later cutting them to length. (Now that I think about it: if you ‘feed’ the long wires from the top through the holes and then soldering them to the driver, that might be even easier.)

I was already planning on swapping the SST-40 in my SC18 to a SFT-40, but I’m not sure if I find it worth the trouble to swap the driver wires (and maybe a spring bypass), since I just want it to be a bit more ‘throwy’ and don’t care for maybe a few more lumen. (I’m also looking for a 5 degree TIR, but haven’t found one that fits, since the TIR used by Sofirn is a bit higher/taller than the TIR’s I could find on Aliexpress.)

19

Wait, does the SST-40 have such a high Vf that the 6-7A max it has will work?

20

Its a rather high Vf curve near the peak, the XHP50.3HI is a pretty low Vf, and with a few supporting mods (spring bypass) the light could gain quite a lot.

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