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 . 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 .
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
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 As far as I know Clulite makes rabbit lamps (hunting flashlights) with old, outdated incandescent bulbs.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.
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
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.
. 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 
.