I have a Lumintop EDC AA light which no longer switches on. Had this light for only a few months and rarely used during that time. Initially light worked fine but now light doesn’t switch on anymore.
On searching the internet for ways to resolve this issue, it was mentioned that the problem was likely due to poor electrical contact between the tail cap (with the switch) and the light body. On inspecting the light closely it seems the only way of making electrical contact between the tail cap and the body is by the very end of the tail cap (which is not anodized) touching a non-anodized small “ledge” within the body of the light.
The threads on both the tail cap and the body are completely anodized which probably makes for little or no electrical contact.
I tested the tail cap switch using a multimeter, and the switch seems to work fine. So the issue of light not switching on appears to be due to lack of (good) electrical contact between the tail cap and the light body.
Suggested solution, I believe, is to remove (some) anodizing from the respective threads on the tail cap and within the light body to enable (better) electrical contact.
So what is the quickest, easiest, and safe way of removing anodizing just from the threads without damaging the threads and without damaging any other component?
No. Light still doesn’t turn on by using a conductive metal object from the negative end of the cell to the inside of the light body (including trying to touch the small non-anodized ledge area within the light body as well).
However, briefly fiddling with the tail cap and the bezel by screwing and unscrewing them I did get the light to turn on briefly (after installing a fully charged cell) but the light beam either soon cut off or flickered off. I tried shaking the light and hitting the light (gently) but the light didn’t switch back on.
I tried several times doing a continuity test between the cell negative and the inside of the light body particularly around the little bit of non-anodized area, but this test failed. Also tried testing the non-anodized area within the light body, and did get continuity (non-anodized to non-anodized). But testing between the non-anodized area within the light and elsewhere within the light body (anodized, I believe), the test failed.
Tested the switch continuity again between the negative spring and the non-anodized area on the end of the tail cap, the test was successful with continuity found.
I think it’s better to find a grease that has good contact so the current can flow more freely though the threads ! ( If there is any problem on the button… !? )
I haven’t read your whole post I just saw “remove anodizing from threads” and I’m here to tell you how you can do that if that’s what you decide to do.
Find something in your house with sodium hydroxide NaOH, aka caustic soda or lye. It’ll be on the SDS as CAS 1310-73-2. If you have lye straight up just mix it with water, more water than lye, and just dip it in. Doesn’t take long.
Otherwise usually oven cleaners, grill /BBQ cleaners, drain cleaners will have some of this stuff. If its an aerosol spray it on a rag and wipe down the part you want to remove, if it’s a liquid you can water it down and just dip it into a cup of the solution. Wear gloves and eye protection. Ventilated room. Maybe a mask if you’re using a powder to make the solution. I kicked up some caustic soda into the air once when I was moving stuff around and inhaled a bit through my nose and Jesus Christ that stuff burns.
All grease is dielectric. Even the best conductive greases, which you shouldn’t really use on aluminum anyways, are 2-10ohms a millimeter. I don’t think that’s the solution.
If i remember correctly there are a few that help with the gap in the threads… !?
Plus i don’t get it, why some flashlight brands are making so thick threads… !?
This is one of the reasons that i really like my Fenix WT25R and Fenix E12 V2.0 , and why it’s better to spend a little bit more money and buy a proper flashlight from a proper manufacturer ! Just my opinion in general lines !
If I may ask, are you using button top or flat top cells?
Also, is there any possibility that the wires in the head may have been damaged (like unsoldering or cut)?
I am asking because I am not sure if the issue is not in the head instead of the tail…
Using button top cell. Flat top cells may not work due to reverse polarity protection ring at the positive input to the light circuit board.
Wires to the LED itself (three of them) appear to be all intact. Please note that at present I can only unscrew the very end of the head with the lens in it (which exposes the LED star circuit board with three wires going to it in the light body); I can’t remove (unscrew?) the actual head part that contains the LED and circuitry (as yet) to check.
Are you thinking of thermal conductivity? That would make more sense. A thermal grease or at least one that’s not super insulating would help with heat transfer from the head to the body if there were gaps in the threads. But the gaps wouldn’t be big enough that electricity couldn’t get through. They’d have to almost not be touching at all. That’s a huge gap.
Thanks for the reply. I was trying to rule out anything related to the physical RPP (as you mentioned, the driver accepts only button top) and any eventual damage to the wires.
I don’t have the flashlight so I cannot help in this case to rule out other situations.
No, there are some greases that help, i know it from Mechanical Mods with 100% Mechanical Switches … ! And also check out the threads on the Mechanical Mods, they are very thin and precise, the current can pass through the “gap” very easily, and they have the arc phenomenon at very minimum level, because of the arc phenomenon there is the black-ish dirt in the threads after quite some time of use… !
According to some posts at reddit, it appears that the head containing the LED and driver circuitry is glued into the light body! And removing the head can be difficult apparently!
What I think I’ll do is to remove some anodizing from the tail cap and from within the light body and see if that resolves the issue of light not switching on or the light only working very briefly for a couple of seconds or so.
If that doesn’t work then It seems I’ll have to remove the head (somehow) and check for any loose connections etc.
There definitely should not be arcing. That’s the entire reason to use conductive grease. That’s the thing you’re trying to avoid lol.
That black dirt in the threads is abrasive and literally almost as hard as a diamond. Thats the stuff they use to make abrasive paste for metal removal. Pretty sure they’re literally turning lubricating grease into abrasive paste.
The main reason to use conductive grease is to prevent corrosion. As an aside, you want the parts to be able to still maintain a good connection. It’s for helping a good connection last longer. It’s not meant to repair a broken connection. It’s not a cable you want to send electricity through.
I bet most of those vapes are stainless steel, corrosion would be slightly more of an issue. Slightly. You can throw a bunch of metals and carbon in the grease without stainless steel reacting to it. Most of them have copper and graphite and you don’t want that on aluminum. There is a kind of flashlight grease people do use that I think has zinc or silver or maybe just graphite in it. I’ve never used it, don’t see the point, especially because they aren’t really clear on what exactly is in it. If it’s graphite that’ll corrode aluminum by itself.
Conductive grease is meant for putting on connections left outdoors or between dissimilar metals so they don’t corrode, so a working connection stays working. Or when your TV antenna was 16 feet tall and in your backyard and you didn’t want it to rust. Not supposed to be for repairing a connection.
Conductive grease will make everything worse. It won’t stay in one place. Over time it will creep to areas where it will cause shorts and malfunctions.
You want to use dielectric grease. Its purpose is to seal the contacts against air so there’s less chance for corrosion. The electrical connection will always be made from metal to metal.
There is no arcing in flashlights. The black stuff is aluminum oxide. Even a small electrical connection is enough for flashlights.
I don’t think the tailcap is the problem in this case.
The reason I asked about if it worked when the switch is bypassed was I believe intermittent issues probably stem from the circuit or wires in the head.
