Are Leds too hot for plastic lenses?

Hello everyone,
im installing new leds in some of my old incans (eveready/Rayovac etc) some of them have plastic lenses.would leds be too hot for them? or do i need to come up with glass lenses?
thanks in advance.

If you mean the kind you buy in stores, they'll be fine.
If you mean something like building your own 300 to say 3000 lumen setups... yeah they'll be too much for the stock plastics.

bykfixer, you Sir are a wealth of info! thank you.
Yes the regular rayovac 30-40 lumen leds.

Incans send out more heat out the front than a led. Led's also heat up, but they send the heat back, and not out front with the light like incans do. Have not yet seen a led light where the beam is so hot it can set things on fire

Thank you jorn!

jorn said:

Incans send out more heat out the front than a led. Led's also heat up, but they send the heat back, and not out front with the light like incans do. Have not yet seen a led light where the beam is so hot it can set things on fire

Click to expand...

Thats about to change now

Cool.
Still not as effective firestarter as a incan. you can see that the video is in fast forvard, and its cut/edited for some reason at ~30 sek. Maby it took too long?
Not like this:
https://www.youtube.com/watch?v=0v29-KEhiAg

Mercyfullfate1777,
The previous generation of Malkoff P60 led drop-in modules - the M60 series - used a 'plastic' optic. The highest output in that series, the M60, produced roughly 230 lumens OTF. There is no better P60 led module than a Malkoff. He used a brass housing to draw heat away from the led emitter, but he was comfortable using a 'plastic' optic lens with this particular configuration. I remember hearing that the reason that he no longer uses the same optic is not because of heat issues, but because the optic he was using would have produced beam 'artifacts' (optical flaws) with the emitter he currently uses in the M61 series. I believe that another very high-quality custom P60 led drop-in maker - CPF member 'nailbender' - offers 'plastic' lenses on some of his P60 drop-in emitter options.

Same with all those insanly bright tripple/quad builds with 4x tir optics. Like the 1600 lumen manker e14 etc. The plsatic optics wont melt. Most of the heat that travels with the light passes straight trough.

Sorry...bad info.

I have some quads which must be 3000lm OTF and the plastic optics are fine. Not sure without nipping up stairs if the tk75 has a plastic lens(think it does off the top of my head) and thats kicking out close to 16,000lm and never melted..................and the heat OTF is crazy HOT . You can heat up and burn your hand from 2ft away................That will burn things for sure(although never tried). One of vinhs quads, with xhp35 HI's inside(7000 ish lumens iirc) burns paper/cardboard almost instantly.............that has optics in.

So plastic lens will not damage plastic lens's afaik.

Those ones op speaks of have soft plastic lenses, not the polycarbonates of today.

Thanks for the info mr fixer

--> as Jorn has already typed.
no problem for the front "glass" because led have way less heat in the beam than bulbs

but the thing is, that You still have to get the heat away from the led, and most of the heat produced goes to the "star" (the led mounting plate).
If that is not in direct contact with the (metal) housing of the light, You will kill Your mod quite quickly.

If You lights are plastic housing - and those models sound like:
* get other ones (from metal),
* have the led run at low current and mount a metal "thermal plate" as big as possible inside (that will still build up heat, but ...)

If the mod are "good" output (full power for else XP-G2, or XM-L2) it makes no sense to start with plastic housings because of thermal problems the light(s) will run into
(Xm-L2 in very short time, XP-G a little longer)

i build 10000lm light with plastic tir and lenses over them, no issues whatsoever, in fact i never had any issue with plastic lenses with leds, no mater how bright.

Eh, if in doubt flashlightlens.com will hook you up with inexspensive glass.
Check'em out.

I use his 'acrylite' lightly frosted acrylic lenses to really clean up the beam of incans and Maglites.
Really cleans up the beam with 90%+ light transmission through them.

The plastics used for optics can easily take any temperature that is healthy for an LED. I wouldn't worry about too much heat for a plastic lens from an LED emitter.

Shouldn't be a problem. The thing to remember is that an incandescent bulb puts a fair amount of the energy it consumes into infrared radiation as well as the visible light it emits. That infrared is what starts fires and melts lenses. A normal LED produces very little infrared compared to an incandescent bulb. If you notice in the video he puts the paper right up into the face of the flashlight, and he still has to blow on it to get the paper past the smoldering stage. Now, if you had one of the multi-LED high high power setups in a holster that closed over the end of the light, and it got turned on while holstered, you might, I say might, get it hot enough to bubble a plastic lens.

Thanks all for your input, i have been trying to use the rayovac 3-4 cell led in two different lights and it wont come on? i even took theled back to the store and got a replacement thinking that one was bad. not sure whats happeneing.

Mercyfulfate1777 said:

Thanks all for your input, i have been trying to use the rayovac 3-4 cell led in two different lights and it wont come on? i even took theled back to the store and got a replacement thinking that one was bad. not sure whats happeneing.

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I would check the polarity of the lights as some lights have a negative (-) "tip" polarity and most drop in PR base LEDs are positive (+) tip polarity and LEDs are diodes so polarity is a must on most of them although a (rare) few dropins can go be used either polarity.
As for plastic lenses you aren't going to melt any if you are modding an incan plastic light without doing some really outrageous modding incorporating huge custom made heat sinks or driving the LED very hard without much heatsinking for only a minute or two.