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Thread: Cold diving and On/Off troubles

  1. #1
    Enlightened
    Join Date
    Jan 2010
    Location
    Quebec, Canada
    Posts
    85

    Question Cold diving and On/Off troubles

    Hi all,

    I am sharing this issue with you to make you benifit from my observations. In this case i only thank Georges from taskled for helping me to solve the issue. I also write this because I am not the only one with this trouble occuring. Remember that when we desing light, we dont test them in all conditions occuring during regular dive.

    Codiak had reported a similar issue in this post:
    http://www.candlepowerforums.com/vb/...=1#post3865138


    Some week ago, 3 divers reported an issue with 3 different canister light with the same trouble. When the light is fridge cold, or even less (tested to -25c in my shed) the light turn On as it should but it wont turn OFF, 20 times in a row. I must unplug the battery to get it OFF. During the dive, water was around 33-32F, and 28F on an other.

    Here is the setup used

    Battery pack is 2s2p or 2s4p for a voltage of 7.4v. Fresh battery from charger, or medium charge dont change the issue. Cold or normal battery dont change the issue.
    Cable is AWG14 40'' long. In the head light, i have a hall toggle switch that is triggered by a magnet. Even if i use a UBER magnet pulling 74lbs the light still won't turn Off. The led module used is the 5x Xre-R2 from DX
    George also tought that magnetic field leaking from the board could mess with his board. I runned the board out of mag head with Awg16 3inches long silicone wire, same trouble.

    I had a good talking with Georges from taskled wich make the hall toggle board. He suggested that i try his board, cold, with an incan light, and it work flawlessly 20 times in a row. He also state that his components are all rated -40c and i trust that.

    My experiments went better, but not perfect when using capacitor on input of HallToggle. We think that something in the DX boost board is going worng with cold, maybe latching too hard, fast, or slow thus reseting the hall board quickly, this one could not complete the OFF operation.

    I did not get in hand capacitor rated for cold use yet.

    Did some of you had similar trouble with the same parts or other parts ?

  2. #2

    Default Re: Cold diving and On/Off troubles

    SmokedCPU,
    For comparitive specs, the light I was using:

    1 x 32650
    LFlex from taskled
    APEM Prolongated Piezo switch
    All wiring is 20AWG Teflon Stranded Wire


    In my case button was inconsistent to the extreme, requiring multiple attempts to power on or off.
    I'm getting the same behavior outdoors in sub zero weather.

    I've yet to do any rigorous testing, but I really get the impression the switch or the JB Weld is not flexing as expected.
    I save this as my HALLSW light of the same design worked fine on the same dive.

    I've a new build I'll be playing with while camping in our local blizzard tomorrow that again uses the HallSW

  3. #3
    Enlightened
    Join Date
    Jan 2010
    Location
    Quebec, Canada
    Posts
    85

    Default Re: Cold diving and On/Off troubles

    prolongated piezo have an internal circuit, this may dont like the cold
    or
    cold may disturb the gap between the ceramic and aluminium cap

    Could you put hand on a can of freeze ??

    you could put something hot inside, like a hotpad, hotshoot instead of in your gloves or foots ..... with this setup you could be able to keep circuit hot but button and ceramic cold ??

    if you have a piezo not installed, freeze it quick and check if it still work, electronic may not have the time to get affected

    keep us in toutch
    such waked trouble like this are funny .... when solved

  4. #4
    Flashaholic* DIWdiver's Avatar
    Join Date
    Jan 2010
    Location
    Connecticut, USA
    Posts
    1,559

    Default Re: Cold diving and On/Off troubles

    I'm not sure I'd want to hit the piezo with freeze spray. The thermal shock may damage the ceramic.

  5. #5
    Flashaholic* lucca brassi's Avatar
    Join Date
    Feb 2008
    Location
    Kocevje , Slovenia, Europe
    Posts
    679

    Default Re: Cold diving and On/Off troubles

    it is possible looks that piezo loses dielectric properties arround zero degrees (like coopolymer ) , so it is hard to (dis)charge '' crystal mesh'' by another tapping (under 120hz ).....page 28

    http://resenv.media.mit.edu/classes/...SI-techman.pdf
    Last edited by lucca brassi; 02-05-2012 at 10:00 AM.

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