The faceplate is made of acrylic, which is the generic name for Plexiglas. Everybody else uses polycarbonate (popular brand Lexan) which is stronger, but polycarbonate turns yellow in a couple of years. Acrylic does not yellow.
i was told by a big light manufacturer that PMMA (acrylic) could not take the heat.
and they said they treat polycarbonate so it doesnāt yellow.
are they blowing smoke?
why are most LED lenses made of PMMA if they canāt take the heat?
iām about to have lenses made and i need to know which to use.
thanks
Iām not an expert, but Wikipedia says PMMA (acrylic) has a glass transition temperature of 105C and polycarbonate at 147C. So if your light is going to be hotter than boiling water, it could be an issue.
Auto headlights are made from polycarbonate and they have a coating to block the UV and keep them from yellowing. Youāve probably noticed how well that holds up.
So I finally got to perform a real-world heat test in the desert last month. It was dusk, 80 degrees F, no wind, and I remembered to bring my thermometer.
Ambient temp, 79.9F
I told my friends why I was running up to my car every two minutes and taking itās temperature, but they werenāt really interested. They just sort of expect me to be doing weird things.
Starting temps normalized to 100 F/ 37.8 C, because my criteria was it would operate in 100 degree weather, parked, with no wind. The real world operating temperature was significantly lower than the prototype on the kitchen floor. A slight breeze came up around the 20 minute mark so I discount the data after that, but overall, I think I can take the advice of BLF members and increase the current from 2A to 3A.
Iām not going to change this light bar, however. Iām going to build a new one with Carclo 26.5mm optics instead of 20mm and use XP-G2 instead of XP-G3. Iāll have to increase the height of the bar from 1.25ā to 1.5ā, and reduce the number of LEDs from 45 to 36 to accommodate the larger lenses. I hate making the bar taller, but the vertical distribution is just too floody. I should complete a 6 LED proof of concept in January, and if the pattern meets expectations, start on El Jefe 2.0
Yes, 4000k. I think itās a little too warm, and 5000k is a little too cool. Iāve been experimenting with using half of each and I like the results.
4500K is the border between 4A/4D (below BBL, rosier) and between 4B/4C (above BBL, greener), so the common-as-dirt 4C would be perfect.
In my S2+ with a TIR lens, which mixes the light better and avoids the fried-egginess of reflectors, the 4C is beautiful. White with just a touch of warmth.
āThough, even my 3000K lights at night just make everything āpopā. Takes a bit getting used to, when everything and its grandmother is ācool whiteā, but once you do, you donāt want to go back. Now, even my 5000K lights look ācoolā.
Ok, I donāt have any pointers. I will however wholeheartedly argue that you are doing something wrong!
I have on several occasions in talking with coworkers and acquaintances referred them to this very thread when they start talking light bars. This project and your dedication to excellence is inspiring and a beautiful thing to behold. Itās things like this that make BLF what it is. Wellā¦there is more of course but to watch a DIY project go from start to finish with such outstanding results is very fun for a geek like me. :sunglasses:
For a proper outdoor light experience Iām right there with you on tint preference. This is of course highly subjective but in my opinion (which I completely agree with), a hair under 5000K just brings the world to life. :+1:
I have a few lights from my buddy Simon in 4C and I love that tint. Theyāre older XM-L2s but my tinted opinion still applies.
Thanks for the kind words. I do tend to obsess over details. The blacked-out grill on my car, for example. I painted it five times before I was happy wth it. My fingers were raw from sanding it down between paint jobs, but now itās perfect. Anyway, Iām sure El Jefe Version 2 will go smoothly wth no hiccupsā¦
Not to be āthat guyā here, but since you mentioned the main reason you plan on going with XP-G2s in V2.0 is for a tighter beam. Considering the timing, I might drop the suggestion of experimenting with the new XD16s. They should reduce the FWHM another full step from the G2 and have similar lm/LED. Additionally, the tint consistency is supposedly dramatically improved along with efficiency through secondary optics. Also, the Vf will stay inline with the G3. That may or may not be a benefit for your driver efficiency.
If being āthat guyā means offering insightful advice to address my issues - then thank you for being that guy!
I missed the threads on the XD16, so I just did a bunch of catchup reading. I think youāre right, it would be a very good fit for this particular application, addressing the problem of too much (many?) lux on the ground in the first 15 meters in front of the car, while sticking with 20mm optics, which would be much preferred to dedoming a bunch of XP-G2s, or a complete redesign with 26.5mm optics.
I will now hold my breath until the XD16 starts shipping.
This is one of the most exciting improvements for me. Cree LEDs rarely let us down on flux, efficacy, cost, availability, and even luminance (esp. w/ HI models). But tint, CRI, and the urine-colored corona next to a magenta-ish spill beam is sure to leave you wanting more. As seen with the HiCRI XP-G3s (maukkaās tests) , they may be high CRI overall, but without a diffuse/mixing optic they are terrible to look atā¦
Hereās to hoping that there is finally a high CRI, high intensity, decent tinted LED that also has good luminance and lumen density.
I have no idea what a 12 volt conversion kit might cost (they canāt be that bad with all that is out there) or how well these lights are āsuspendedā for shock (if they are)ā¦yet why canāt the average off-roader who isnāt tackling the Baja1000 fab up something simple/relatively inexpensive? If I had my Morris or Westgate yard light (150 watts) properly mounted to our side-by-side I would be more than satisfied with the output. They arenāt much larger than the pics above and have decent/adjustable lenses (Westgate).
If it broke?
$200 is just about nothing when it comes to just about everything off-road.
Not taking anything away here from the OPās awesome project or trying to throw this off-topic but wondering if a merging of the two concepts (just as lights are āmoddedā elsewhere) would be worthwhile.