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  1. #1

    Default Anyone have a cell act like this

    Did all items on my checklist, did linear test as I always do, and from beginning of,dive cell acting slow
    See brief video


    Also these cells are about 9 months old,

  2. #2


    Time to replace cell #3. It seems to act current limited so if there is no water on the cell face it is time to replace.


  3. #3


    Is it a Maxtec 305F cell? I bought a unit that had one of those cells that was only a couple of months old and was super slow and complete junk. Either way, definitely time to replace it.

  4. #4



    The second mouse gets the cheese!

  5. #5
    Join Date
    Apr 2015
    Arizona or traveling


    It’s dying a slow, painful death. Swap it.

  6. #6
    Join Date
    Oct 2004
    Spartanburg, SC


    Did you do a linearity check @ 20'? What was the linear deviation in air? Cell seems to be limited however it could also be deviation.


    The Light Dude
    Innovation through exploration

    Local Zip Code Diver

  7. #7


    No offence intended, but if such a cell behaviour is unclear to you and you are not certain about the appropriate response it might make sense to reconsider rebreather diving (especially in caves) or at least get additional training..
    just saying..
    this should not be a surprise no matter how old the cell is..
    a cell can die/act up at ANY time.. this is why most systems use at least three..
    Cells are the weakest point in the system, I sure hope you at least called the dive..
    understanding O2 cells is in my opinion the MOST critical part of rebreather diving, especially in advanced dives likey cave or heavy deco ceilings..
    at minimum do yourselve a favor and read, re read, discuss with instructors/mentors/rebreatherbuddies the following two articles which greatly sum up the overall situation in regards to O2 cells..

    another surprise is that I seem the only one concerned about the lack of understanding of cell behaviour..
    this is the stuff that kills most on rebreathers.. not understanding cell behaviour and wrong response to it..

  8. #8


    Replace cell 3, it looks like it is current limited. If you don't think it is, then swap it to a different position and try again, then it is the wiring (but most times it is corroded then, so you can see it). But I would not prefer to do it on a serious dive. Becoming current limited can happen at any time, even during a dive where it first looked good. And even calibration can be fine but still current limited (I had this behaviour one time after 100 minutes diving and 90 minutes deco left, I thought it is moisture as the cell was only 6 months old, so dried the cell, calibrated it again for the next dive next day and even the 1.3 was fine the first 20 minutes. Then it dropped again, I called the dive, replaced it and all was fine).
    And I find the difference between 1 and 2 already quite big too. Did you calibrate? I normally don't have a 0.07 difference between cells. It is within the limits, but if I have this on my ccr I would start to worry about the cells. I normally don't have a bigger difference than 0.03.

    Last edited by Germie; 02-25-2018 at 12:01 PM.

  9. #9
    Join Date
    Jun 2011
    St Petersburg, FL


    I'm susrprised this is perplexing. Im not a rb diver and understand the likely cause.

    Sent from my iPhone using Tapatalk

  10. #10


    Click image for larger version

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    Thank you so much for bringing this serious issue to light. I had a similar occurance after my dive Saturday and I was extremely worried. At maximum penetration, my second cell dropped to a dangerous .2 and flashed RED! I did an o2 flush and got my other cells up to 2.4, but that cell only raised to .7. Fortunately I was able to maintain that level for my hour swim out and 47 minutes of deco. My buddies think its because I took an antihistamine before the dive. I read once you're not supposed to do that.

    Anyway. I'm not convinced it isn't something wrong with the cell. What batch is yours from? Maybe if we can find others, we can get the manufacturer to recall them. Wait. I just looked at my cell again and it says "Do Not Use After", followed by a date. Do I need to replace my rebreather after that date? This is starting to get expensive.


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