<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Jon, this is great news. When I make oil filled lights, I remove the reflector covers, the little cone things. I find the scattered light is better than a beam. <div>Hank<br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Sent from my iPhone</div><div dir="ltr"><br><blockquote type="cite">On Feb 19, 2025, at 8:10 PM, Alec Smyth via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr">I love that you're doing research like this. Years ago I used some very similar lights to those, but oil filled. They worked all right, but eventually started leaking oil. Epoxy sounds very attractive by comparison.<div><br></div><div>Best,</div><div>Alec</div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Wed, Feb 19, 2025 at 1:26 PM Jon Wallace via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div> <br>Hello folks, I have initial results of an epoxy filled off-road LED light. In summary, today I ran the light in 80F (26C) air and bright sunshine for 30 minutes without any hint of burnout. I held the unit in my hand at the 25 minute mark and it was uncomfortably warm but not hot enough that I couldn't keep hold of it for the remaining duration of the test. Water will obviously be factors better at dissipating heat so I feel this 30 minute test, at least in the short term, is adequate to demonstrate the feasibility of using epoxy instead of oil compensation for certain off-the-shelf LED lights.<br><br>Unfortunately, nothing is gained without some cost. Two ramifications I've observed with this daylight test are a reduction in brightness and change in beam pattern due to the epoxy. Comparing against an identical LED unit that has not been modified my light meter is showing a brightness reduction of 33% by the epoxy filled LED. Additionally, the beam pattern has changed from a spot/flood to pretty much a flood although there may still be a highlighted spot that I can't discern in the bright sunshine. It's possible that the change in brightness is the result of the beam pattern change more than loss of light through the epoxy since a more dispersed "flood" is going to appear somewhat dimmer than a "spot" even with two identically rated units.<br><br>Since I do not have experience with oil compensated lights I cannot assess how they change brightness and beam pattern compared to an epoxy filled light. However it seems reasonable that oil compensation would have the same effect to some degree (maybe worse) and therefore this is just the tradeoff inherent to make an off-the-shelf light waterproof. The epoxy method at least adds the benefit of being maintenance free compared to oil compensation methods.<br><br>There is one variable that I will be exploring further. I completely filled the cavity of this test unit rather than just using only enough to cover the LED elements and electronics. The cavity is 3.25 inches diameter and 1.25 inches deep with a volume of 11.18 cubic inches (sorry, you metric guys will need to convert) and so there's quite a bit of epoxy for the light to travel through. For my second unit I will begin by only using enough epoxy to cover the electronics (about 1/2 inch or 12mm thickness) to see if that results in less impact regarding brightness and beam pattern.<br><br>LED LIGHT<br>Tiger Lights TL500F, 4 inch, 50 watts, 6900 lumens<br><a href="https://tigerlights.com/products/50w-compact-led-flood-light-generation-2-tl500f/" target="_blank">https://tigerlights.com/products/50w-compact-led-flood-light-generation-2-tl500f/</a><br>These units retail for $130/each however I purchased pre-Christmas when they were on sale at Amazon for $113/each. They are well built with heavy cast aluminum housing, aluminum pcb and have thermal paste between the pcb and housing.<br><br>EPOXY<br>Let's Resin - $31.49 (51oz)<br><a href="https://www.amazon.com/LETS-RESIN-EPOXY-Epoxy-Bubble/dp/B0CP7MPD15?ref_=pd_bap_d_grid_rp_0_1_ec_cp_pd_hp_d_atf_rp_1_t" target="_blank">https://www.amazon.com/LETS-RESIN-EPOXY-Epoxy-Bubble/dp/B0CP7MPD15?ref_=pd_bap_d_grid_rp_0_1_ec_cp_pd_hp_d_atf_rp_1_t</a><br>Follow the link and you can read all about it. My results were excellent with a clarity of glass, 1.25 inches thick and absolutely crystal clear. It is very low viscosity and slow curing with a long work time. I mixed 4 oz of resin with 2 oz hardener (2:1 ratio) and mixed/stirred for 5 minutes. As expected many bubbles were introduced during mixing so I allowed the epoxy to sit for 45 minutes after which all the visible bubbles had disappeared. Vacuum or pressure cycles would remove additional remaining dissolved air in the mixture but I did not have my equipment with me to do that step. Because of the slow cure time (48 hours) I covered my LED unit with a box to prevent dust or other small particles from collecting on top of the epoxy. I allowed it to cure for 48 hours in temps between 75-80F.<br><br>I think the key to success with these type of high power off-the-shelf LED lights is aluminum PCB's and thermal paste between the PCB and housing. I suspect units utilizing fiberglass PCB's and/or lack of thermal paste would potentially result in overheating and LED failure, at least in air. With water as the heat sink maybe even these would survive however I'll leave that to someone else to test.<br><br>The final test for me will be viewing the epoxy light at tonight to see if they "appear" bright enough for underwater use given the measured 33% output reduction compared to the non-modified unit.<br><br>Jon </div> _______________________________________________<br>
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