Corrosion on new charger point

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  • Hi guys,
    I just received my banglejs (damn custom's took that long!). Concerning this matter with corrosion is there something I can do beforehand to avoid any issues?

  • May be it is possible to gold-plate the contacts? Like here­old-plating-Super-Simple-/

  • Thanks for the suggestion but I was hoping for something simpler. Like the nail-polish that someone mentioned here. Would that work without doing any damage?

    I mean not being able to use it for running or generally workout (if sweat makes such damage) kind of degrades the devices usefulness a lot .. From my perspective it is exactly the reason I purchased it. Being able to track my workouts in a privacy-friendly way.

  • As I mentioned earlier in the thread, I found that the simplest method was to use a small piece of strong tape.

  • Really need to look for a reliable and easy way to avoid corrosion. I don't want to varnish the contacts, but to glue them with tape is not elegant. Although I think someone can do it neatly and beautifully.

    As an option: peel off a small circle from the computer mouse, you know, there are several of them on the bottom of the mouse and stick it on the middle contacts of the watch. It is enough to glue one contact.
    You can also use a piece of double-sided tape + something. If the tape is thin.

    Guys, suggest more ideas, it looks like many will come in handy :)

  • Although I think someone can do it neatly and beautifully.

    I think this turned out pretty ok...

  • I don't get how yours is protecting the contacts, @johan_m_o.

    I used some transparent varnish, but it's easy to remove if I wish to use the contacts in the future, or to apply something else if it doesn't work.

  • It's just a small piece of gorilla tape over the two middle contacts... Sticks very well, but still quite easy to remove if needed.

  • Ok, call me stupid if I'm missing something, but ain't the contacts still exposed?

  • The two middle contacts, the ones that matter, are completely covered.

  • Oh, ok, it's a transparent tape! By the photo I thought you carefully made a circle on a black tape for each connector, lol

  • I thought so too, so thank you for being the one to say it ! ;)

  • @Serj wow, very interesting about the LG watch. 2014 though - I'd have hoped that SMA might have learnt from that :(

    Transparent tape definitely seems the way to go if you can find something that sticks well. I'm currently trying to source some appropriately-sized stickers that I can pre-apply to the next batch of watches.

  • Are these actually gold layered copper contacts or slices of brass rod?
    The traces on the contacts of my Bangle.js 2 remembered me of what is seen on the screenshot (don't know the english translation of "auf der Drehbank von einer Metallstange abstechen").

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  • I think it is gold-plated copper PCB, because it seems possible for the contacts to come off completely.

    As mentioned in my replies above, I really strongly think that plating with some other substance (like gold) will not solve the underlying problem. About the only way to fix things properly is to insulate the middle two contacts

  • Sorry may be I was not clear. I proposed (additional) gold plating to avoid corrosion on the charger contacts as well. I agree that "data" contacts should be isolated because they are not in use for 99% of users.
    May be we should inform the vendor about the issue, not sufficient gold plating.

  • Hi just an update. Have put the varnish on ( cleaned with isopropyl alcohol before) . As can be seen in the photo corrosion seems to be continuing but charging has not yet stopped , starting with a bit of a wiggle 🙂). Where is the atmosphere hole people talk about. I was a bit liberal with the varnish and didn't want to block the hole .

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  • The hole for the barometer is on the top of the watch under the strap pin, so nowhere near the charging connector.

  • I put some transparent acrylic paint sold als acrylic finish (used for art paintings) on it. On my second watch I used white arcylic paint since it is easier to see if it's still on the watch. If you paint carefully the transparent finish cannot be seen.

  • I've used some transparent varnish, but I think I'll replace with black acrylic paint for the same reason you used white: to be sure that it's there. I think it's holding up, but I'm not sure and I also think I'm getting some corrosion so better safe than sorry.

  • Hi All,
    I have a "second wave" Bangle, which came with the little piece of tape covering the two central contacts.
    However, after I while it came off, so I replaced it with another cut which succumbed, as well, after a couple of months.
    I'm a little bit worried since the two outside pins are starting to oxidize and, as it happened with an Amazfit watch, this can make impossible to charge the device.
    Now I painted the contacts with a laque, but I wonder if there any way to solve this issue one for all.

    Also, is the voltage on the two central pins somewhat related to CPU activity? Because after using the watch with an app which I developed, continuously running in the background, it seems that corrosion has kicked up after a day or two.


  • Hi! Sorry to hear this - this is actually the first I've heard of the tape coming off and we've been shipping with it for 4 months or more now. I'd say lacquer/paint on the middle two contacts is definitely the most long-lived option though. I'd be amazed if that moved.

    The issue is actually just the SWDIO pin (second from the right -­ware-swd) which has a something like a 10k pullup resistor to 3.3v on it inside the chip itself, which we can't turn off. It's always there though - CPU activity won't have an effect at all.

    On a subsequent version I'm looking at having the pins disconnectable in software (and maybe usable as USB + GPIO), but realistically because that means a new board design we're looking at Bangle.js 3 (some way off!) rather than Bangle.js 2.2 :)

  • The issue is actually just the SWDIO pin (second from the right -­ware-swd)

    Ok, this is strange as the tape shifted a bit on the right side, leaving part of the left-central pin (SWDCLK) uncovered.
    An the corrosion occurred mostly on the leftmost pin (GND)

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Corrosion on new charger point

Posted by Avatar for user136815 @user136815