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  1. #11
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    Ok, there doesn't seem to be a secret use to the 4th cell that I wasn't expecting.

    I was after a constant PPo2 computer so the fact it plugs in is just an extra. I'll run with three cells.

    I can see the advantage of just being able to swap the wires around to use the "spare" 4th cell but I'm too much of a chicken. I'd sit out a dive rather than start taking the head off the unit on deck.

    Also, whilst my intention is to monitor the main handest primarily, the mono screen is a bit shit in the dark. If I end up looking at the OSTC first, I'd rather it was mirroring the same cells as the vision.

  2. #12
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    Mark, your highlight of my quote seems to suggest shock at the frequency of the cell changes?

    I don't think that's something I could be persuaded to change.

    Once they've spent a year in the unit and 4 months as a spare, you're certainly welcome to any of my 16 month old cells.

  3. #13
    Old but keen Mark Chase's Avatar
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    Quote Originally Posted by NWdiver View Post
    Mark, your highlight of my quote seems to suggest shock at the frequency of the cell changes?

    I don't think that's something I could be persuaded to change.

    Once they've spent a year in the unit and 4 months as a spare, you're certainly welcome to any of my 16 month old cells.

    Its confusing as the post suggested you change cells every four months?

    I was trying to get my head around the routine?

    Am I correct your using used cells as spares? That seems counterintuitive?




    Personally new cells scare me I like ones with a proven track record.

    In the last 14 years on CCR I have had several cell failures, most on new cells

    I have only had one cell fail after performing perfectly and that was back in the great APD Bud cell drought. I ended up running my buds for 18 months straight whilst awaiting the new cells from APD. Eventualy of course one failed and became current limited but Id logged over 270 hours on it, so that was cool by me.

    Once APD released their new cells I had multiple cell failures within 1 -5 dives 12-15 hours on unit

    I eventually switched to Narked @ 90 cells and once again got consistent performance.


    I run 3 spares in sealed bags for 12 months then put them in the unit for 12 months staggered over 9 dives (unless used in the mean time) and buy 3 more spares.


    The great APD cell drought and subsequent APD crap cell period taught me one thing.

    Cell failure is no big deel just so long as your on top of it.

  4. #14
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    I change one of three cells every 4 months. On rotation. That way they all spend 12 months in the unit. Plus they're not all the same batch so unlikely to fail together. Mostly, it spreads the cost over the year.

    I keep the cell that I remove for the next 4 months as a spare. I prefer this over keeping a new spare. I know that the "old" cell has been working recently. A new one is an unknown quantity.

    4 months later, that cell gets chucked as I replace the next one. So the "old" spare is actually only 12-16 months.

    If I have a cell failure, replace it with the spare and then that doesn't work properly... I'll just write it off as a bad weekend.

  5. #15
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    So similar to yourself. I'd trust a cell that's been proven over a brand new one.

  6. #16
    Coastal Member dwhitlow's Avatar
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    Quote Originally Posted by NWdiver View Post
    I change one of three cells every 4 months. On rotation. That way they all spend 12 months in the unit. Plus they're not all the same batch so unlikely to fail together.
    I aim for a similar cell rotation. Cells are a consumable and are not expensive. When factored into the overall cost of diving cells are a small cost.

    The consequences of being wrong with cells might not be pretty and should not be inflicted on those you dive with.

    I recall watching a John Lamb presentation about oxygen sensors and concluded:
    - avoid fitting new cells from the same batch together
    - avoid replacing more than one cell at a time
    - avoid using a cell for longer that 12 months
    - avoid using a cell older than 18-24 months
    - often check cell performance at the end of the dive
    - don't bother checking cell performance when dry, or at the start of the dive.

    Anyone willing to take risks with oxygen sensors should be reviewed under rules #1 and #2 here and is unlikely to meet the demands of #6 because they are a fool trying to look and sound cool.

    Quote Originally Posted by NWdiver View Post
    I keep the cell that I remove for the next 4 months as a spare. I prefer this over keeping a new spare. I know that the "old" cell has been working recently. A new one is an unknown quantity.

    4 months later, that cell gets chucked as I replace the next one. So the "old" spare is actually only 12-16 months.

    If I have a cell failure, replace it with the spare and then that doesn't work properly... I'll just write it off as a bad weekend.
    I used to keep my new and sealed spare in my 'hand luggage' (the bag of shit I always take on the boat) and found it was getting replaced at regular intervals by less prepared divers needing it and buying me a replacement. Having cycled in my last new cell (the old one being the current #4), and with little expectation of any worthwhile diving, I am having a think about cell management for next year.

  7. #17
    Old but keen Mark Chase's Avatar
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    Quote Originally Posted by NWdiver View Post
    So similar to yourself. I'd trust a cell that's been proven over a brand new one.
    Interesting way of doing it.

    Not heard of that system before?

    Have to say I am pretty relaxed about cells these days and dont consider them the threat I once did

    so IMHO what ever cell rotation you have is fine just so long as you stay on top of them


 
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