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Thread: Strange Cell Readings

  1. #1
    The Evolution of Diving diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob's Avatar
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    Hybrid Meg

    MCCR Dolphin, Evolution

    Strange Cell Readings

    OK I don't know why I seem to be having cell issues these days but here is another one and this one I have never seen before.

    I was doing my pre dive routine today and during the function test and Mv checks I noticed that one of my cells were reading 0.25 in air when the others were all reading 0.21 (as they should) so I decided to do a calibration. After calibrating I could see on my APECS handset that all cells read 1.00 at 100% and 0.21 in air (as they should). My Shearwater was also reading 1.00 at 100% but I still had the issue with the one cell reading 0.25 when the others read 0.21.

    I then thought to switch the cell into a different slot to see if the wiring was the issue. As I was fiddling around with the wires I could see the Mv reading change and so I thought I had found the issue (faulty wiring). After playing around a bit more I discovered that the same issue happened in different cell positions in the head with the same cell but not the others so I broke out the Volt Meter and checked the individual cell. The reading in a static position with the molex contacts facing directly up was 10.2Mv as I rotated the cell so the molex contacts faced down (180 degrees in the opposite direction) the Mv increased to as high as 11.7! I repeated this several times and then confirmed it by repeating it again in the RB head.

    That confirmed to me that the cell was damaged somehow and I have now replaced it with a fresh one. I have never seen this before or even heard of it happening before but I thought I would share it with you guys incase you have a similar situation where you can't figure out why a cell is not reading correctly.

    I would have never picked this up had it not been for the SW computer. The APECS has a two point calibrating system and takes the Mv reading in air and 100% so on the APECS after calibration it looked like all the cell were reading correctly but on the SW the error was obvious which lead me to do further investigations.


    For those who are interested here is the cell info;

    Type - ISC (Vandergraph)
    Date of manufacture - March 2013
    Date the bag was opened - 26 Dec 2013
    SN of cell - ISC102425


    Rob

  2. #2
    RBW Member PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG is a glorious beacon of light PeterVICEG's Avatar
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    Meg

    Fenzy PO68 Dolphin

    Re: Strange Cell Readings

    Did you read the Mv from the apecs hadset?

    Peter

  3. #3
    The Evolution of Diving diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob is just really nice diverrob's Avatar
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    Hybrid Meg

    MCCR Dolphin, Evolution

    Re: Strange Cell Readings

    Quote Originally Posted by PeterVICEG  View Original Post
    Did you read the Mv from the apecs hadset?

    Peter
    Yes the Mv change was the same on all three devices Meg, SW and stand alone volt meter

  4. #4
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Hollis Prism 2, Megalodon

    CCR Instructor Trainer

    Re: Strange Cell Readings

    Rob I had a cell (old ai IIRC) that would change readings just from installing the head. I took the head off and bumped it around and mv reading went all over. Changed the cell before diving.
    Cheers,

    Dave....

    www.wedivebc.com

  5. #5
    Probably sleeping Dr.Yen is an unknown quantity at this point Dr.Yen's Avatar
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    PELAGIAN

    Re: Strange Cell Readings

    I just had 3 cells out of 4 do the same. Same as yours, Vandagraph manufactured Mar 2013. I had one still sealed that I opened yesterday to replace one of the bad ones and it did the same straight out of the package. Not impressed...

    Yen

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