Gutting a Clulite SM610 and modding with a COB - what do I do for optics?

Flashlight Modding and DIY Parts
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Hey all.

I have a Clulite Smartlite SM610 (eg see here), an old incandescent light with a knackered 6V SLA battery. I’ve been wanting a light I can mount on a tripod for a bit as a bit of a “floodlight” and it would be a shame to chuck this out when it’s a good size to mod to do this.

It’s just the right size for me to make up a 5x6 pack of 18650s – e.g. with Sanyo GAs in 10s3p would make for a 37V 10.5Ah / 388Wh pack – which gives me a heck of a lot of leeway at the business end.

I’m wanting at least 2hrs of runtime, and with as many lumens as I can get :slight_smile:. Reasonably good CRI would be nice also, and a CCT around 4000-5000K. I’ve been looking on Farnell at some of the larger high rated COBs - eg the Cree CMA2550 series - but also I want a tighter beam than the typical floodlights these seem to be used in. The kind of thing I’m after is a bit like a car headlight I suppose? I want a lot of spill to light up the area but it would be handy if there was more intensity in a centre spot for some “throw” to aim. For what it’s worth, my main purpose is to use for archery practice in the dark evenings, in an unlit compound with no power :grin:.

The SM610 already has a reflector in it (plus spares available here) though I have no idea whether it’s parabolic - I might email Clulite and see what they say. I would have to cut the bottom of the reflector off a bit to place the LED properly in any case (the 45 degree angle is a few cm in, I guess since the incandescent bulb throws some light behind it). From what I remember the original main bulb was very throwy with minimal spill… but the beam quality was a bit naff.

Anyway, beyond trying that I’m totally lost what I should be trying to do in terms of optics. I had a look on the Ledil site but all of their reflectors for this COB look like the sort of thing used on indoor bulbs? Alternatively maybe I’d have more success trying to squeeze in e.g. 4 more standard high-power emitters, or getting a lens like Sirstinky’s light here? A lot of the optics stuff I’m looking at seems to assume small emitters instead of great big honking COBs!

If anyone a bit more clued up on this than me has advice it would be greatly appreciated :slightly_smiling_face:

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Hi there, good idea youve got there to bring some new life into your old clulite. As far as I know Clulite makes rabbit lamps (hunting flashlights) with old, outdated incandescent bulbs. You said you wanted to install a larger COB emmitter into the light, it may be bright but the beam will be very wide and not throw far. (The bigger the surface area of the led, the bigger the beam).

Id suggest you choose a reflector and led combination. Reflectors can be had in kaidomain in all shapes and sizes. I have no idea where to get large diameter TIR optics, maybe try convoy flashlight or MTN electronics.

You also have to choose a “throwy” led to get your desired beam. Make sure to pair with the right driver and voltage.

Sbt90.2= best overall for long range. High brightness but very expensive and uses lots of power. Does overheat.

Sfh55 (or similar) = cheaper and brighter. Good balance between spot and flood. Needs high current.

Osram cslnm1.tg. = extremely narrow beam, long range but less bright. Lower power.

Sft40 = narrow beam and decent brightness.

Sft70= 6v with larger emission area

Xhp 50.x high intensity, xhp35.x high intensity. Good beam and brightness, make sure to get correct voltage.

EDIT: that COB led you were looking at is 34 volts, that wont work with 18650s which are 3.7 volt unless you find the correct boost driver. Maybe task LED has something like that but its unlikely it will work. Most of my suggestions are 3,6 or 12V. Make sure to check. They should be compatible with commercially available flashlight drivers.

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I’ve done a couple of lights (old ones with incandescent to LED and Li-ion conversion) this way. It took a lot of work to get them to where they worked reliably and were usable for more than 10 minutes at a time. I think one I had over 120 hrs total over like 2 years into it before I retired it due to unfixable issues with the batteries.

Here’s your checklist/points to consider:
Heat sink is critical. You need a big one for high power LEDs or active cooling (like I did) and thst requires a step down controller for the fan, mounting, etc.
You need a special driver for that cob led that can provide 36 volts to 38 volts output. TaskLED makes ine specifically for that (HyperBoost). That driver however requires extensive modification to get it to work and it isn’t cheap (if you can even get one). Plus if you want modes (or variable brightness) that adds complication.
Led choice determines your optic. Using a big cob led requires extensive reflector tuning and modification unless using an off the shelf one designed for a cob. You can get them from Aliexpress.
A standard SMD led like a xhp70.3, SFH55, etc can use a compatible off the shelf reflector, or you can mod the existing one to work. However…it’s a lot of work and trial and error.
Batteries. You have that sorted out, but you need a BMS system and a way to charge them. I used a balance charger (cheap Chinese clone). Your V out should be as close to the LED Vin as possible if using a cob. A standard 3 volt LED is much easier to drive and you can use readily available drivers.

Hope all that helps. I gave up on these projects because off the ahelf flashlights have gotten so good and way more affordable than anything I can build or mod anymore even. L

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In that case a COB LED won’t do–due to the huge surface area, it takes an insane amount of power to produce even a tiny bit of throw. You are much better off with one of the SMD LEDs we use here, like the XHP70.3 HI. This way you can also find lots of compatible reflectors and optics, Convoy sells loads of them.

This video gives you a sense of the beam profile you’ll get with a COB: all flood and no throw. And keep in mind that the secondary optic you use will be way smaller than the reflector in the video, which means you get quite a bit less throw.

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I’ve occasionally browsed these on eBay and thought about an LED conversion, the biggest headache if you want high output, in my opinion, is the heat sinking.

You could run a modern LED at low level without too much difficulty, but this goes against your desired output requirements.

Unfortunately I think that your expectations are a little high: 388Wh battery pack and runtime of 2.5h is 155W… using an efficiency value of 125lm/W, you’d be producing c. 19,400lm. This will require significant modification of the host to prevent thermal stepdown or catastrophic self-destruction.

You might be able to strap a bunch of heat sinks and pump to the outside and water cool the thing, but water cooled LED projects are pretty uncommon so it’s hard to give specific advice.

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Gaggione has various ~70mm TIR optics for COBs. They also have a flat ~67mm UFO optic, with a very short focal length of 12mm. Using that would let you fit a bigger heatsink in your host. It will be floody though.

Otherwise there are various large faceted or OP reflectors that will work.

Here is a link to the Ledil search function, where you can set the search parameters. I set it to COB, with minimum LES of 10mm, to get you started.

Smaller LEDs on MCPCBs paired with multiple reflectors would be an alternative approach to a COB, but it is a bit more involved to put together. You could get your LEDs, optics, and centering gaskets from Convoy in this case.

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Thanks all for the replies. In the interim I contacted Clulite who do sell the reflector which would fit without the secondary hole in the one I have (model number LF40). As it stands I’m leaning towards not using this.

Looking at their website they seem to have started making LED models with lithium ion batteries now! It looks like they even still use the same casing (e.g. SMLED-L2).

The problem with this approach is that I’m not going to get near the output I want without 3 or 4 emitters, and at that point I feel I may as well be using a COB? Not to mention efficiency gains of underdriving a big COB vs overdriving small high power emitters.

Not a prob – I’m an EE so I’m pretty comfortable with the electronics side of things, I’m planning on building my own SEPIC driver based around one of the off-the-shelf controller ICs (a cursory search brought up the TI LM3429 which seems suitable enough). Hence the idea for a fairly high voltage pack.

Thanks for this list :slightly_smiling_face:. BMS and charger are as yet undecided, I’ve never made a bigger pack like this so I guess it’s a learning experience. For the driver I was going to put together my own as above, and I was going for active cooling like your own. It looks like I’m going to try off-the-shelf optics and see how they work with a big COB.

Funnily enough I found this thread in the meantime where the CXB3590 was being used with some of the LEDiL reflectors. Annoyingly it’s mentioned the LENA series of reflectors are better but I don’t think I’d be able to fit one without some serious trimming as I have about 104mm diameter max, but the Angelina series has some that could work - e.g. the Angelina-M which has a tested width of 54° FWHM.

In some sense this video does show something close to what I want. I say “throw” very loosely, I’m really after what I guess could be called area lighting, but I don’t want “pure flood” with no optics where the light fall-off from distance just makes it useless past a very bright first few metres – hence the comparison to “car headlight” (I feel like they’re quite well-optimised for an even field of light?)

I’m definitely not expecting to run anywhere close to 155W continuous :slight_smile:. If I use the heatsink I have to hand (old i7 CPU cooler designed for 77W TDP, I think the CPU TjMax is about 105°C) I will only be able to sink around that 77W figure (actively) so of course I’ll be underdriving the emitter quite a lot.

This looks quite interesting, thanks. As you say it might be quite floody – though they list a 22m diameter COB having a min FWHM of only 28.9°. Wouldn’t it also be at the “throw” setting with the emitter further than the 12mm focal length? Or am I mistaken in how that works?

I’ve considered this but it sounds kind of annoying to do. I have considered that if I use a significantly smaller diameter reflector that I could mount it lower in the opening already present and then have a more traditional high-power LED + reflector above it though, to use either separately or in tandem.

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The 12mm focal length would be the throw setting, closer than 12mm would be floodier. You can tune the beam in this way, but don’t expect it to be throwy like an aspheric lens or large parabolic reflector. I’ve got the 45mm UFO optic and have paired it with an XHP50.3 HI in a D Mag build. The throw setting is more of a medium flood. It doesn’t make a tight spot like an aspheric lens or a large parabolic reflector. The beam is very nice though, with no artifacts or perceivable tint shift. It is also pretty efficient and doesn’t lose efficiency regardless of how it is focused. So if you want a short optical setup for a COB, with a little tunability in regards to the beam profile, the UFO optic is a good choice. It doesn’t require glass in front of it, being as textured as it is. Scratches would go unnoticed and wouldn’t affect the beam.

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I would go Bridgelux Vero29 (or maybe another model) instead of the cree CXB3590. I ended up designing my own refelector adapter for the Bridgelux as Ledil decided to discontinue the one I had planned to use. I got it 3d printed SLS nylon via JLCPCB. I believe Lena and Lenina both mount to it.

In my experience with these big COBs, you generally want a fairly narrow beam reflector because even with a narrow “beam” the COB still has a TON of spill for flood.

The driver I’ve been playing with for ages with the Bridgelux is “only” 45w but the big COB is so efficient at that low power, I think it still makes like 9k lumens or at least in that ballpark. I power mine off a Milwaukee M18 pack as it is just really convenient and the voltage range works out nicely.

I really wish some lunatic would make a sort of modular driver that could run something like Anduril2 but use a power board that could drive the big ~40v COBs at ~100w.

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Any reason in particular you’d go for the Bridgelux over the Cree? I was mainly looking at the Cree models since they’re easy for me to get from Mouser/Farnell/RS/etc.

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You will definitely have more configuration options and better beam control if you go with individual 3V LEDS, or 6V etc., rather than a COB.
If you do not want to drill and tap the heatsink for MCPCB mounting, you could glue the MCPCBs to it with thermal epoxy. Use minimal adhesive, just a small spot in the center of each MCPCB. Weight them down while curing. The adhesive would not be irreversibly permanent because it will be possible to pry the MCPCBs off later if needed. Convoy MCPCBs tend to have a rolled edge, otherwise, file the edges to 45 degrees to make them easier to remove.

The heatsink could be a forged one from Wakefield. You might be able to fit one of the 130mm x 30mm ones in there, and add a fan, and cut some vents in your host. If the 130mm one won’t fit, there are 78mm and 68mm ones and so on. The fan could be powered by an inexpensive dc-dc regulator board from AliExpress.

The reflectors could be, for example S21A OP or S21A SMO from Convoy.

You could set it up with two separate drivers, with two different LEDS and optic combinations, for separate SPOT / FLOOD. The center LEDs could be floody high CRI, and the outside LEDs could be Osram WF1, in S2 reflectors or whatever.

The battery configuration could be 1s or 2s, etc. rather than needing a high voltage lipo pack. With a low voltage setup, you have a lot of flashlight drivers to choose from. Using protected cells would give you LVP, which you might want if your dc-dc regulators etc. could otherwise drain the batteries too far if accidentally left on.

You could enter this build in the Old-Lumens challenge. :grin:

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From what I’ve seen, the Bridgelux Vero / VeroSE series just have better options for Ledil reflector mounting and to some extent, they’re just as available in small quantities though you will have to search multiple vendors. You’ll likely have to basically make your own list of who stocks which models / color temps / CRI. Years ago when I picked up the Cree COB, I think only the low CRI variants were available in small quantities.

Two of my goals were ease of assembly and a reflector that had a commercially available snap on front lens.

IMHO, COBs are better than individual LEDs in almost every way so long as you can come up with a solution to power them and you’re okay with their size. Small LEDs CAN’T hit the same performance numbers without using an absolutely silly quantity and then it just becomes entirely too expensive.

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Screengrab of my modified Ledil Lena series mount.

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Uses 4x M3 lowhead screws through the COB to clamp it to the heatsink where, I believe the discontinued part it was based on, was designed for just 2x M2.5

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