DIY Hunting LED Spotlight - design suggestions

Wurkkos

bammo

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Sep 26, 2011
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Hi Guys,

I have a small 4WD buggy used for spotlighting foxes on the farm. It has a Lightforce Blitz 240 mounted on the roof and we recently converted to HID in an attempt to improve throw and reduce current draw as the alternator is pretty small. Its not been a success and I want to try scratch building an LED spotlight for long range work. I have a workshop and tools (lathe, mill etc) so the fabrication part of the equation isn't a concern but looking for advice on the LED source to use and the lens and lens arrangements I should consider.

Range and tightness of the beam are the primary objectives. A clean focused beam that reaches out to at least 300m
Size / weight not a big factor (its perma-mounted)
12V source (so may need DC-DC) but want to keep current draw under 6A if possible
Needs to be water resistant (rain)

I am thinking a 5" / 125mm aluminium tube with a single very large LED (15W?) / supply /heatsink at one end and a focusing lens at the front.

Thoughts?
 

LEDphile

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Mar 8, 2021
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I agree that the Ledil Seanna TIR is a good choice for this, but the XHP70.2 isn't going to give you much throw (estimated just under 300k candela). I'd look at using the Cree XP-L HI (est. just under 500k candela) or the Cree XM-L3 (est. 350k candela but almost double the lumens and a slightly wider beam). In either case, you'll need an LED driver capable of 3-5A output, along with some good thermal management of the heat from the LED (think metal-core or ceramic PCB, a good thermal interface material, and a big heatsink)

Edit to add that the Cree XQ-E HI will give you about the narrowest possible beam out of that optic, with candela in the same range as the XP-L HI, but lower total lumens due to the narrower beam. But the XQ-E HI package is a bit more of a pain to design around for high-power use, due to the lack of an electrically isolated thermal pad, so wouldn't be my first choice for an LED to use if I were just starting out.
 
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alpg88

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Apr 19, 2005
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seanna will give you 4 degree beam with xhp70, sure xpl will have more lux, or a narrower beam, but it it will also give you useless in real world, pencil thin beam, with 4x less lumens.

i actually had awesome results using led engin 84mm tir, and xml2 leds, it was made for LZP 12x12mm led, but the mounting of that tir is tricky, especially when in an application with a lot of vibrations, also it was made for a different led with special 26mm mcpcb, so it would require fabricating a collar to mount the tir firmly.

but if leds used are; xpl/pg... then i would use ledil iris 4 degree tir, the ones with a narrow tunnel, (thou 4 degree rating is for xpe die), i build a light with 4 of those with xpg2 leds, it throws farther than 98% of lights i have, and still has very usefull spill.
 
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LEDphile

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Mar 8, 2021
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Some more detailed numbers:
I worked primarily in US units, but 1k ft is effectively 300m within the precision of the data used. I've assumed a 90% transmission lens on the front of the fixture for weather resistance.

The takeaway here is that while the LED solution will probably give you a tighter beam than the existing HID solution, you'll need 4 of the XP-L HI option to give you the same illuminance at distance as you get from one of the 70W HID fixtures. So basically no power savings

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JustAnOldFashionedLEDGuy

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Nice work LEDphile. Were you assuming the 50 or 70W HID. I got 3x XP-L HI for the 50W HID. Of course, we are assuming this was the Lightforce Blitz HID and not some other HID. The OP is not clear on that.

OP, did you buy a Lightforce Blitz HID, modify it yourself, or some other HID?
 

LEDphile

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Mar 8, 2021
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Nice work LEDphile. Were you assuming the 50 or 70W HID. I got 3x XP-L HI for the 50W HID. Of course, we are assuming this was the Lightforce Blitz HID and not some other HID. The OP is not clear on that.

OP, did you buy a Lightforce Blitz HID, modify it yourself, or some other HID?
Comparison was to the 70W HID, on the assumption that if the OP was looking for more output, they'd go for the more powerful upgrade. So 3x XP-L HI to match the 50W seems about right
 
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