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Thread: Copper and Aluminum Don't Mix

  1. #21

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    If you feel you're getting true corrosion, as opposed to normal oxidation of aluminum and copper, then I would try some sort of barrier between the two.

    As mentioned, the double-sided thermal tape works pretty well (not as well as thermal compound, but.....).

    Is it possible that your led is inadvertantly grounded to the copper heatsink, via the aluminum star base? that would generate a potential, and vastly increase the likelihood of corrosion between dissimilar metals.

    Any part of your "+" or "-" leads that aren't insulated, touching the aluminum star base, could provide a path for current. You would hope to notice the extra drain, but maybe not.

    The newer Lux rebels are electrically isolated from the star base, but IIRC, the older LuxI, LuxIII, LuxV, etc may very well not have been. That would put the base as a ground path, any touching copper as a ground path, and if some other part of your saber hilt were also grounded, you'd get current flow through the starbase and copper, instead of just through the LED.


    Thoughts to ponder
    Last edited by Arkhan; 08-05-2010 at 11:52 AM. Reason: added comment about older Lux star bases not being isolated from the LED?

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  2. #22
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    Quote Originally Posted by polarcupz View Post
    I will try to get a pic when I get home. Oh and thanks fender, that is really nice of you, very supportive. Whatever. It is all over the bottom of the lux V, not as much on the copper...but that is how the corrosion is supposed to work (copper will eat away at the aluminum).

    If this thread should not be continued I will let it die, along with my lux V.

    I WAS supportive. The first time. After that it just seems like problem mongering where this isn't one. It would probably shock you at the numbers of MHS systems that Tim has sold with copper heatsinks over the years. This hasn't been a problem. At all.

    Like mentioned before, if you have corrosion, there is something wrong that YOU'RE doing.
    Last edited by FenderBender; 08-05-2010 at 12:18 PM.

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  3. #23

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    Quote Originally Posted by FenderBender View Post
    It would probably shock you at the numbers of MHS systems the Tim has sold with copper heatsinks over the years.
    I was going to say:
    Don't you mean that Tim has sold?
    But then I realised there was no error of grammatical here

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  4. #24
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    Yes, while The Tim should be mentioned with proper respect, I did mean to put that

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  5. #25

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    Quote Originally Posted by Arkhan View Post
    Is it possible that your led is inadvertantly grounded to the copper heatsink, via the aluminum star base? that would generate a potential, and vastly increase the likelihood of corrosion between dissimilar metals.

    Any part of your "+" or "-" leads that aren't insulated, touching the aluminum star base, could provide a path for current. You would hope to notice the extra drain, but maybe not.

    The newer Lux rebels are electrically isolated from the star base, but IIRC, the older LuxI, LuxIII, LuxV, etc may very well not have been. That would put the base as a ground path, any touching copper as a ground path, and if some other part of your saber hilt were also grounded, you'd get current flow through the starbase and copper, instead of just through the LED.


    Thoughts to ponder


    It must be a short then. I haven't really picked the saber up in a long time, so I wouldn't have really noticed the extra drain. Thanks so much!
    Last edited by polarcupz; 08-05-2010 at 01:14 PM.

  6. #26

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    Nobody wants to see your LED get eaten alive and destroyed. Just because something *rarely* occurs, doesn't mean it isn't happening to you right now.

    That it *is* happening should point to something wierd, or not quite right.

    I would definitely check to ensure there is no grounding issues with your led/heatsink assembly and the rest of the saber.

    If everything is correct, you should NOT be able to measure voltage between the heatsink and the "-" terminal of the battery regardless of saber being ON or OFF.

    EDIT:

    I looked at www.luxeonstar.com The Lux1, Lux3, Lux5 *all* specify that they do not have an electrically isolated base, and steps must be taken to ensure electrical isolation between the star base and the rest of the saber. The Rebel Star base is isolated, as was the K2 star.

    End EDIT:


    Fenderbender or others have probably diagnosed 50 times more saber related problems than I have, so if I'm leading you on a wild goose chase, I hope they'll step in and provide some gentle correction.
    Last edited by Arkhan; 08-05-2010 at 05:39 PM. Reason: verified luxeon star isolation

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  7. #27
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    No, you are pointing to a plausable explaination. My point was that the initial post was about the MHS system being faulty because of the mixed materials was bogus. When things like this happen, there IS a problem, but it's not the MHS. The electrical problem is a good place to start, especially if there is an in hilt recharge set up and there are bare wires touching the star. IIRC, it was mainly the red family of LUX's that had the isolation issues, but that doesn't mean that the whole line couldn't have them as well.

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  8. #28

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    It is just ironic that the original question turned into all of this. Isn't it funny how things work. It is corrosion but not likely that it is the fault of only the two metals.

    Sorry guys for all of the trouble and thank you for your help. I had this saber completely apart, and was reworking the wiring when I noticed it. I will have to check the connections.

  9. #29

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    as I pointed out earlier, thousands upon thousands of computer CPU heatsinks have been sold that combine a copper core with aluminum fins. The two are tightly interfaced and that precludes any sort of electrical isolation.

    That thousands and thousands of these heatsinks have not corroded and destroyed said systems is a pretty good indicator that simply putting aluminum and copper in contact with each other is not a bad idea.

    The MHS heatsink design is not a recipe for disaster.

    That this person *is* seeing corrosion should point to something wierd, and not support a claim that the MHS system "is bad" with its heatsink materials.

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  10. #30

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    Quote Originally Posted by Arkhan View Post
    That this person *is* seeing corrosion should point to something wierd, and not support a claim that the MHS system "is bad" with its heatsink materials.
    I wasn't claiming that anything is wrong with the heatsink or the MHS parts or the materials. I was just asking a question in the beginning. The connection was MY fault on the lux v thus the corrosion. Thanks for your advice.
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