Prototype off-road/boating spotlight - King COB!

I have to eventually get a proper driver for this; the Stratus LED driver is rated for 3.5A at 28V, so when I connect a 3s LiPo to the driver, I cannot turn the dimmer pot all the way. No problems with a 2s LiPo, but the output is not as bright. I have a driver for this that works off 110VAC that I will incorporate into a nice outdoor flood light for the house. The Stratus LED parabolic reflector’s LED aperture fits exactly over the 3590 ’s LES which is nice, and as far as I can tell looks like it’s perfectly focused.

I also have some nicer COBs, Cree CMA3090 that are CRI90… but they run at 3.6A at 48V. Trying to dissipate 172W of heat will be fun…

I’m actually curious just how much heat they actually need to dissipate. It can’t be the full input power since some of that is being converted to light.

I modified my mount and added some heatsink compound and then ran the CXB3590 at the maximum that my bench psu will do which is ~36v and 2.0A. Anyway, with the Dell heatsink, it definitely needs some airflow so I tossed an old 80mm computer fan running at just 5v near it and the temperature stabilized and started dropping.

Are you sure the output of the Stratus driver is only 28v? It claims to be a boost driver and maximum input voltage is 28v but I can’t find anything that says what the output is besides 3.5A max.

For what it’s worth, this is the variant of CXB3590 I got.

https://www.arrow.com/en/products/cxb3590-0000-000n0hcd50g/cree

5000k and 80cri seemed like the best compromise of those that can actually be purchased. The CMA3090 series looks to be a bit smaller, less efficient and there is no option for 5000k in the 90cri.

I e-mailed Stratus LED about modifying their driver for a higher output voltage. Looks like the COBs they use are nominally 24v so, 28v would be plenty for them. However, they claim their driver can not be modified for a higher output voltage.

For efficiency, it looks like your average modern LED is able to convert anywhere from 20% to 25% of input power to light so you need to dissipate 75% to 80% of the input power as heat. I actually thought this number would be higher but it seems the maximum theoretical efficiency for a LED is somewhere around 40% so we might see 250lumen/watt some day.

Well, I was looking for something a little smaller than the 3590. And I had a typo, it was CRI80 (at 4000K). Not really too worried about efficiency

They do have 5000K CRI90, you just have to buy it in multiples of 1000!

True, but I try to figure in a bit of overhead, as I may be operating these in the hot and humid summer months here in NY.

The AC-DC driver I have is a MeanWell HBG-160-48B

As to the Stratus LED driver - I’m trying to remember where I saw that, or maybe I mistook input voltage… Don’t remember? Might have to test it with the 3090s…

Hrmm. I didn’t see a 5000k 90cri in the datasheet.

This looks like the Dell heat sink I’m using…

I actually have two of them that I pulled out of some old Pentium4? machines. I don’t know what the lower plate is made from but it feels like some really soft aluminum alloy as it is pretty easy to bend.

I may try to find a smaller heat pipe based heatsink but this Dell unit is actually kind of nice since the fins are fairly thick and so they’re not sharp.

Have them in 2-step, 3-step, and 4-step… and you only need to buy 50, not 1000! Group buy? :money_mouth_face:

Off a server, may have been Xeon chips… Looks like a nice heatsink. I wish I saved all the ones I had; threw them out when I moved; used to rebuild and repurpose PCs for friends and family.

I just used the cheapest Thermaltake heatsink, then went into my pile of Mic-6 drop-offs and milled an adapter plate; it has a recess for the 3590, and I used MX-4 thermal compound. It’s almost as if the Stratus LED reflector was made for the 3590 as it fits perfectly; though there’s very little room for the solder joints.

I spent some time last night collecting data and parsing the datasheet for the CXB3590 and noticed some interesting things.

This LED is extremely efficient around 30w. It hits around 190lm/w and produces ~6000lm.

As input power increases the efficiency falls off but even at 12000lm, it’s still operating around 170lm/w

I did some research on DB Custom’s modded Fireflies E07, and he’s hitting 10000lm at something like 100w input and of course, this is only for a few seconds as the whole thing overheats and the cell starts crying for mercy.

I seriously think that we could build something like a Convoy L2 with 2s or 3s 26650s and maybe more heat sinking on the head that could do 10000lumens fairly sustainably. It would require a custom driver though as I don’t think the hyperboost can handle the input current that this would require.

Have you looked at the LEDiL Stella lineup? Thought of doing something like this myself and I figured, with such a large heat sink, that cutting the size of the reflector down would be good thing. You would also gain some level of waterproofing and be able to switch lens according to you needs.

https://led.cdiweb.com/datasheets/ledil/15186-Ledil-datasheet.pdf

https://led.cdiweb.com/products/detail/FN15186STELLAHB-LEDiL/602330/pid=468

https://www.mouser.com/ProductDetail/Ledil/FN15186_STELLA-HB

I saw the LEDiL Stella mentioned in the optics thread. The model above looks pretty good for my purposes. 90mm is kind of huge but I guess it is what it is…

If Arrow had it, I’d buy it right now. Gotta love that free overnight shipping.

I only just realized the CXB3590 is ~50mm diagonal.

The hyperboost is good up to 7A max input I believe. But you’d need to find a way to shoehorn it into an L2 host. Methinks one of the 4s soda can lights, along with LEDIL optics, would make for a pretty cool host

The 6A~7A input current limit means that you’d need a minimum of 5s to get close to full output. This isn’t really a problem for my Navy Battle lantern retrofit project but for a “hand cannon” it probably is…

A soda can light would have a very hard time dissipating the ~100w of heat. I had a similar idea but put a big heatsink and fan between the LED and the batteries.

That’s what I was thinking myself. A nice finned heatsink, possibly actively cooled, would be pretty awesome. Now to find a cheap host.

Would love to see that Navy lantern retrofit when you get to doing it!

There is the led treiber senser xtreme:

https://pcb-components.de/anleitungen/Xtreme_E.pdf

I ordered some of their other stuff (haven’t used yet) but looks promising…

That driver would need a minimum of 5s as well. 4s could drive the LED at full output when the cells are fully charged but it would drop out of regulation or exceed the input current limit fairly quickly.

I’m actually curious if either the Hyperboost or the Led Treiber Xtreme have input current sensing. I suspect they do not and so it would probably be safer to run both off a higher input voltage so that the input current never gets high enough to damage the driver.

I think I want a driver that can handle about 20A on the input. I would also prefer something that can not generate voltages above 50-60vdc as above 60vdc can be seriously dangerous or lethal.

I was looking at the LT8391 last night but I’m not an electrical engineer and so electrical things I design typically just follow manufacturer design guidelines.

I redid my spreadsheet a little bit and so if we assume we’re going from 4.2v to 3v per cell the hyperboost would need 7s and the Xtreme would need 6s.

For testing shenanigans, I just happen to have some 7s4p NCR18650GA battery packs. I think one of them would run the COB at full output for something like 3 hours. :laughing:

Me neither… The LT8391 is not exactly plug-and-play either. I thought I could find a dev board to make life easier, but as with most things that are fast and easy, it don’t come cheap:
https://www.digikey.com/product-detail/en/linear-technology-analog-devices/DC2345A/DC2345A-ND/6674142

LEDiL also makes some reflectors for the CXB3590!

https://www.ledil.com/search/?manufacturer[]=Cree&names[]=CXA%2FB+3590&q=

Looks like they work with the solderless COB connectors… Which is convenient… Might have to pick one up to try out for the back yaard light. I do have a cheap 50W COB floodlight that was given to me because of a bad driver. I replaced the drive with a DC boost from MeanWell (about $10) so I can run it off a LiPo to make it portable.

I’ve got all their datasheet for CXB3590 compatible optics open right now. It is really fascinating how the different LEDs produce different beams with the same optic/reflector attached. For instance, the 30 degree reflector produces a 27 degree beam.

I’m probably going to get a FN14074_STELLA-HB to use and a F13380_ANGELA-M to play with.

Although the F13325_ANGELINA-S also looks interesting.