Streamlight SL-20 family - LED mod ideas

Streamlight SL-20X family - LED Drop in Project

Hi, I have been looking at the Streamlight family of lights, and in particular the SL-20 family. The older models used 1/2 D cells, and the newer ones seem to be based on 5 x sub C cells. The seem to be quite well made and potentially a good host for a multi LED host.

At one time, these seem to have been a LEO standard, but I am not sure if that is still true or not.

I saw that JS converted a few to higher powered incan setups, but I am interested in a pure LED setup.

Has anyone done anything like this lately?

Harry

Re: Streamlight family - LED mod ideas?

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HarryN said:

Hi, I have been looking at the Streamlight family of lights...

I saw that JS converted a few to higher powered incan setups
Harry

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Would you mind PM'ing me the links to those? Thanks.

Techjunkie said:

Would you mind PM'ing me the links to those? Thanks.

Click to expand...

Hi - it is even easier. Type in sl-20x in the google search bar at the top of the page - there are perhaps 10 useful threads in it. JS is more or less out of that business as I understand, but you can ask him.

I am just about to buy a "Streamlight SL-20X LED" model for this project. It has the 5 sub C cells in series and a very decent quality body. The plan is to use this host, a 6 amp driver board I am working on (in the electronics forum) and do a full LED conversion.

The attraction of it for me is that it is 6 volt (so a buck circuit can be used), it uses Sub Cs, which are always improving, and it already has a "low LED setting " built in, so I can be lazy with multi level power.

You need to be really careful on which body you pick, or you will end up with one of the polymer ones, which are not as useful for LED conversions IMHO.

It is actually a pretty decent light in its own right, so doing a conversion that is substantially better is not going to be all that easy. I just want to do something different.

Ok, I actually found the thread you were interested in. Funny what you find when searching for something else.

https://www.candlepowerforums.com/threads/98951

Well, after some searching I finally tracked down a pair of Streamlight SL-20X lights. These are the older 5 x 1/2 D based R Ni-Cad setups.

You might ask the perfectly acceptably question - why the heck would I pick these up? Well, this light has such a following that you can hardly buy one, even beat up. Also, everyone else is doing mag mods, so what could I possibly contribute to that knowledge base?

The plan is to keep 1 in "stock condition", and play with the other so I have a reference to compare against. Even though they are rated at a mere 200 lumens, they have a heck of a lot of throw - routinely 20 - 30,000 lux. That is a rating not easily achieved with a 200 lumen LED package.

Should be interesting.

BTW, if you are reading this thinking that the project will magically go from vapor ware to finished, beautiful light in mere days like some of the semi-pro modders around here, then you don't know me very well. Maybe by Christmas if things go well.

The plan is to use the 6 amp driver board I am working on (see the electronics section for the thread) and some LED + optics / reflector not yet chosen. Most likely either K2's or Luminus, but nothing is completely off the table yet.

I can't believe I am starting another flashlight project.

Take care,

HarryN

I am just thinking out loud here.

These lights in incan format push around 20-30,000 lux, so they are pretty decent throwers.

What kind of LED + optics or reflectors setup should I consider to get in that general range?

I have about 5-6 amps total to play with, but the driver output is limited to 4 volts, so I can only make it 1 LED or 2 LEDs wired in parallel (not series)

I am considering:
- 2 x K2 TFFC driven at 2 - 2.5 amps with a pair of nominal 20 mm something to focus it.
- 1 x SST 50, driven around 5 amps with pretty much any size focus setup that can be fit in there.

- The P7 will not fit the way the light and electronics I am using are designed.
- 2 x MC-E is possible, but still limited to about 20mm dia optical solution, so I am not so sure about throw.

Suggestions?

HarryN said:

...
What kind of LED + optics or reflectors setup should I consider to get in that general range?

...
I am considering:
- 2 x K2 TFFC driven at 2 - 2.5 amps with a pair of nominal 20 mm something to focus it.
- 1 x SST 50, driven around 5 amps with pretty much any size focus setup that can be fit in there.
...
- 2 x MC-E is possible, but still limited to about 20mm dia optical solution, so I am not so sure about throw.

Suggestions?

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Definitely the SST 50 @ 5A and a full size (~50mm?) reflector. You just can't get good throw with those milti-die or large emitters and small reflectors.

Hi Harry

I think you have mentioned before that the key to throw is a tight focus and this is only really achieved with a large optical aperture to LED die size ratio.

With this in mind I've been playing with some optics/single die LEDs to see what can be achieved with my limited resources.

I've been able to get a projected image of a luxeon rebel die with a size 4cm * 4cm at a distance of 1m with a single 38mm aspheric.

Looking at the distance between the LED and the lens and assuming a lambertian radiation pattern, I reckon that I should be collecting about 80% of the available light, with a transmission efficiency of approx 92% for uncoated crown glass. The estimated of effciency of this solution is about 73%.

If we push a rebel ES to 1A, that should produce about 225lm (according to datasheet) and this number of lumens focused into an area of 16cm^2 at a distance of 1m gives close to 100,000 lux. Should be good for throw, but not much good for lighting up a back yard...

Hi - Thanks for the inputs. There is a very interesting beam shot pair in this thread by LED Zeppelin, post 50.

https://www.candlepowerforums.com/threads/240843&page=2

In it, he compares a reasonably large reflector (mag size) with an SST-50 to a quad cree with nominal 20mm reflectors. No doubt, that SST-50 is an amazing LED package, but for throw, the quad single die package setup has more throw - at least it appears so in the pictures.

Billynomates - 100,000 lux That would be amazing - maybe I should let you do that one first, as you seem to be further along down that path.

HarryN said:

Billynomates - 100,000 lux That would be amazing - maybe I should let you do that one first, as you seem to be further along down that path.

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I'm sure I'll give it a go at some point - need to get the test rig into a fit state to take it out doors first (the garage isn't really big enough for 'throw' testing). Oh and I'll need to buy a lux meter to see if my rather generous predictions actually hold out. The problem is that the basic meter I was looking at tops out at 50k lux

In case anyone is following this thread at all, the project has evolved into a more general project of a "drop in" for the SL-20x family.

I managed to buy a couple of these used, but it is surprised me just how hard it is to pry these out of the hands of their owners, or worse - for them to imagine a "modification".

Anyway, after receiving them, I fired them up on the ceiling against a 2D mag at full tight focus - wow - no comparison. These things are definitely built like a tank, and have very impressive center beam throw, decent smooth drop off of the center beam.

The corona is kind of useless IMHO, but that is a personal aspect.

In any event, I am working with a few others on the project, testing out a few configurations, different LEDs, waiting on parts, etc. Possibly around March might have some early versions for sale.

The goal is a "drop in" that is
- Rugged
- More lumens of course
- Reasonable throw
- Self install by average owner
- Approximately the same current draw and run time as the standard bulb
- Priced to be interesting for a typical existing light owner

Easier said than done.

If at all possible, please post your questions / comments in this thread - I am notoriously bad at responding to PMs.

BTW - assuming this all works out, I will not be selling these directly, but instead use some of the great existing sales channels that exist for flashlights and parts. I don't do the paypal / credit card / sales thread stuff very well, so I will leave that to the people that enjoy it.

It is nice to post some progress. The first prototype board for the light mod arrived last night and even works. This is more a solid beginning than anywhere nearly finished, but very helpful.

Now if only the optics would show up.

I had a question for potential users. There are a couple of versions of the SL-20X:
- The original single bulb
- The - LED version
- The polymer versions.

It is unlikely that this drop in will work with the polymer versions due to lack of a thermal path.

Any sense of how many people have the "original" vs "LED" version - and of course - actually use it.

Thanks

HarryN

I still carry a SL20X in my squad and use it almost every shift. I would love to upgrade this light. you just can't beat these work horses.

Good luck to ya.
Chris

Hi Chris - Thank you for the words of encouragement.

I picked up a 3rd one on Friday - this time an SL-20x-LED model. Now I have two of the "older and well used" SL-20X versions and the newest "led" model.

The SL-20x-led is somewhat like the Surefire aviator - incan main bulb, and 3 surrounding leds, each type on its own switch button. The incan is for throw, the LEDs for up close work. Improvements wise, it has a higher rated throw (lux) by 25%. It also uses higher capacity 5 x sub C cells vs 1/2 D cells.

The downside, IMHO, is that both beams are really not very good, at least indoors. Frankly, I was kind of surprised at the beam quality. There are a lot of rings in the main beam - but those might not matter outdoors - still need to try that. The LED "close up" led beam was useful for paperwork, but definitely not flashaholic quality. Its not a huge problem for me, as I will just build an LED drop in to swap out both beams.

One rather annoying point is that I had hoped to make one common module for both the SL-20x and the SL-20X - LED, and this might not work. This is where I could use some input from end users.

The SL-20x-LED I have has very straight, cylindrical internal walls in the head, making for a robust, but thinner wall.

The two older SL-20x's I own have a large beveled edge on the inside, then it comes down to a straight wall. (sort of a holder for the reflector). This makes for quite a thick wall.

If a few people can look at their lights where the bulb + reflector assy goes in, and tell me if their SL-20x has the bevel first or just a straight wall, I would appreciate it.

Thanks

Harry

HarryN

My SL20X has the bevel . I also have the SL20XP Led. To get the rings out of the incan beam take painters tape (blue masking type tape) mask off the upper portion of the reflector take some clear tape and mask off the bulb and sputter the area left lightly with clear krylon and it cleans up the beam nicely.
Also for a easy mod to the SL20X get a Fivemega 9AA to 3D adapter and fill it with 6 AA batteries and 3 dummy AA batteries and use the SL35 bulb.

Thank you for the reply - that information helps a lot.

Changing over to the other bulb is a useful idea - but I am an LED guy and want to make a drop-in for this light that will work with the standard battery packs.

It is funny what makes a person like a light. Sometimes it is just cool, small, ultra high tech, brightest, perfect beam, etc. These lights are really none of those, but are rapidly becoming my "go to" light. It is just so convenient, easy to find, and a good balance of the LEDs for short range and the incan for longer range use that make it really useful.

I thought it was just me, but my son is always using it as well - and he is has no skin in this game. Of course, he is anxious to see it setup with "more power" as well.

We took the SL20x and the SL20x-led down to a local park last night to shine on trees. There was some, but little difference in useful throw. Nonetheless - very handy and good range - well over 50 yards - maybe 2x that.

The LED short range lighting is making me think about converting the older SL20x into a sort of -LED version as well. Might be possible with some playing.

The optics for the LED package are due to come in next week - should be intersting.

Hi HarryN, I'm very interested in a drop-in. I have had an SL-20x incan for about 15 years now, which I use at work, and love it. I much prefer it to a Magcharger because of the feel in my hand as well as the pre-focused beam, which I happen to think is just about the perfect blend of throw and spill for me. I do use it with the SL-35x lamp and had upgraded the battery to a 4000 mah 1/2D nimh. Although I love this light the way it is, I would definitely be interested in LED if the lumens were higher and the beam was similar. Also my light does have the bevel in it. I will be watching and waiting eagerly to see what you come up with. Thanks for your time.

Scott

Hi Scott,

Thank you for the comments and interest. I don't have the mag charger, but I agree these lights really grow on you. The ones I purchased second hand are dinged up, and I am proud of it.

I have not tried the sl-35x bulb assy in it (yet), as my goal has been to match the run time of the original bulb assy, but with more light (of course).

I have not tried the 4000 mah 1/2 D packs yet - where did you get them?

The thing that is interesting, is that I sort of don't like having two different kinds of battery packs, and that has gotten me interested in upgrading the two older SL-20X lights to be the -LED version (sub C pack) I am thinking that with a few parts, this would be possible, but have not tried it yet, and probably will not until the drop-ins are selling.

As far as progress on this drop-in, I am still bench testing everything, but running it off the SL-20x-led flashlight body. After a lot of searching, buying and testing:
- I have narrowed down an LED + optics / reflector setup for the main beam. I have a working bench proto, slightly mangled, but working.
- Determined that my original drive setup was not going to have enough power to run at the desired light level, so obtaining a higher power driver is underway. There are no commercial drivers that will power it easily, so I am having to do a bit of electronics work with BillyNoMates to pull it off.
- Nearly settled on an LED + optics / reflector combo for the secondary beam (low / - LED setting)
- Working though obtaining secondary parts, connectors, etc.
- Working on the board(s) design

I am pretty happy with how it is going, but it is challenging to match the lux level of the very tiny central spot of this incan light. I would not call this LED beam a flood by any stretch, but the hot spot is larger and more even than the standard bulb design.

It should not have surprised me, but I really did expect this project to be a bit easier and cheaper than it actually is. I suppose that is why there are no really great drops-ins for this light on the market. It is amazing just what small item can take a week or two just to find a part and even more time to integrate into the drop-in.

Anyway, thank you for your interest.

HarryN

Henry,

I got the 4000 mah pack from a website that is no longer online, I think it was from Australia. I did read on here that some people had issues with them though, fortunately I have not. www.batteryjunction.com has the 3500 packs for a decent price.

How many lumens do you think your setup will put out? I was hoping for something approaching that equal to a P7 or MC-E. If that isn't possible or budget friendly with the SL-20x, then I guess I would possibly seek something for a 3d mag, or just keep the setup that I have now and hope for something in the future.

Scott