Potting Drivers - Budget reversable option?

Flashlight Modding and DIY Parts
61

I love what you are doing and want to see this light at 9 amps but just be aware that the MTG-2 turns into a mini heater that could warm a small town at that current. Good luck.

62

Thank you MRsDNF. I was planning on high being more of a "turbo" mode. I figured the light would not be able to handle extended high based on what you have said about your MTG2 DST. Your light has much more heat sinking than mine.

In actual usage, I tend to use low and sometimes medium. I just like having a kick ass high available. With only 3 18650's, run time on high would be pretty limited too.

63

Kick ass I like. I haven’t given up yet on a 9 amp MTG-2 yet. Construction is underway on a new light.
A lot would not agree but the DST would have to be the best cheapest large reflector light around. The plastic reflector will not short on the electrics and I have not managed to melt one yet with all the abuse that I have thrown at them. Looking forward to your upcoming night shots. :bigsmile:

64

OK, Got my Silicon Carbide. According to below, the GE Silicone II's are neutral cure silicone rubber compounds. The Silicone I's are acid cure. So a whole range of cheap products like this are available to make the potting compound.

http://www.caulkyourhome.com/frequently-asked-questions.php#prod_9

My understanding is that Alkoxy cures are better than Oxime cures for copper and certain polycarbonate plastics. I'm guessing the above products are Oxime as Alkoxy cure compounds are more expensive. I hear Dow has a couple product lines (737 and 236) that are Alkoxy, but I haven't found a local store carrying any of this stuff yet.

I plan on trying it this weekend. My 7 amp XM-L2 DST has unsoldered the positive LED wire on the driver side twice now. Hoping this helps pull enough heat out to stop that. But more important, I hope it helps keep the resisters and such cooler.

65

Thanks for this info! Good to know about the GE Silicone II! That's readily available! Just wish I knew about it when I was at Home Depot on Monday! Let's see if I can add another exclamation mark! :)

-Garry

66

http://www.amazon.com/dp/B000HBGI8K

Auto parts store. "Sensor-safe", "Low odor and non-corrosive formula" = no acid. Cures stronger yet easier to remove than household silicone caulk. I can't for the life of me figure out why you guys are dead set on scouring the planet looking for anything other than the Ultra Grey.

67

So Comfy, would you suggest mixing the Ultra Grey with silicon carbide? Or just use it by itself? Of course I am thinking about my situation with the LM2596 modules. I am still mounting them to an aluminum bar either way.

-Garry

68

Comfy, why would I want to pay the same amount for a third of the amount of silicone? I would if it was better. Like if it was Alkoxy cure silicone (it's not).

I also worry it may have tin too. My understanding is that some of the RTV products contain tin.

69

Is there an advantage to having something that hardens? Would something like this work?

http://www.homedepot.com/p/Super-Lube-3-oz-Tube-Heat-Sink-Compound-98003/202932736#.UldTsPmBqGt

70

That would run and leak into the light for my application. I need something that hardens enough to not run, but still be removable.

I use that paste you linked to sometimes, but only when I have too. It is is very hard to completely clean the residue off just about anything and it interferes with soldering. It may appear to be cleaned off, but has real staying power.

71

Thought you might be interested in this, I modded a Convoy S6 for a fellow BLFr the other day. Decided to stack chips on the spring side and pot them with Arctic Alumina to protect against a possible short. After everything was said and done, the light only worked in Hi mode. Frustrated, with no other drivers on hand, I managed to peel the AA off the stacked chips, remove the chips, find the problem (the SinkPAD was shorting thermal pad to neg pad, invisibly…can’t find it but it’s there whether an emitter is mounted or not) and restacked chips to complete the build. Didn’t pot again. lol But the point is, it wasn’t extremely difficult to peel the Arctic Alumina off the stacked chips without doing damage.

This was some 1 1/2-2 hours after it was done. I have no idea if it would still come off clean after using the light for a while.

72

I agree that AA it can be cleaned off. I've done it myself many times and alcohol helps. Just exploring for a better, more budget solution.

73

I picked up some Permatex Blue RTV silicone as it was $2 less than Ultra Grey and the only noticeable difference I saw on the packaging for Ultra grey was that it was rated for "high torque". The blue still says "sensor safe". So this is ok to use right? Is it better than Plasti-Dip? About the same?

Pics:

-Garry

74

Cool Garry. Do you plan to mix it with Silicon Carbide?

I picked up a tube of GE Silicone II, but I haven't done a pot yet. I hope to this weekend. What I don't use for potting drivers, I will use around the house.

Please keep us posted. Do you have thread in progress that you will be using this stuff in?

75

Just my Lawnmower mod thread (Best Way to Run an XM-L from 12v Automotive Source).

Should I be considering silicon carbide? Is it worth it?

-Garry

76

Only if you need the potting to help remove heat. I've tried to read that thread a couple times, but the electronics stuff was just too far over my head. Sounds like you are doing more installation stuff now. I will have to go check it out.

77

BTW - that Blue RTV was only $3.97 at my local Walmart. I'm looking at this 400-grit silicon carbide. No idea what grit to buy. Only $6.54 with shipping for 1/2lb.

-Garry

78

I definitely need to remove heat! That's what's stopped me from proceeding. I'm working on getting the backs of my modules mounted to an aluminum bar which will then mount to the mower frame.

OR is it just better to use the Home Depot Super Lube heatsink compound? I'm guessing that compound doesn't harden though and could make a mess.

-Garry

79

Huh? What you talkin' 'bout Willis? Who's talkin' 'bout reflectors shorting??? You posting in the wrong thread? Not had your morning coffee yet? :)

-Garry

80

I bought a half pound from that same vendor. It arrived in very fast. Like a couple days. I think I ordered Sat and got it Tuesday.

400 grit sounds good to me, but this is all new to me. I got 120/220 and 1500. The 1500 looks way too fine. I hesitant to use the 1500 because I have a beard and can really get a good seal with a mask..