Cell replacement policy.

dave t · 22nd June 2007, 07:23

I Know Mike is going to shout at me again but..........I dont think it makes any difference whether you change all three at once or rotate them from different batches and different ages, the important thing to understand is cells are CRAP! new or old and they should not be trusted. I have seen them fail after three weeks, after six months and also last two years, I have seen them fail slowly and seen them die rapidly. I just had one cell that performed flawlessly for four months just die within one hour long dive.

What is MOST IMPORTANT is every diver learns to check his cells in as many ways as possible on EVERY dive. This "I just love to check my milivolt output to ensure my cells are good" is just bullshit

Dave

**DeepBlueInnovation** · 22nd June 2007, 07:29

OK, all these statements are well and good, but will someone provide a reason why these things occur.

Dave I appreciate you listing the problems you have had with cells, but what I would appreciate even more is an explanation of why these things occur, based on rational analysis.

Why does a cell fail after three weeks?
Why does a cell fail after four months during a one hour dive?

Drmike · 22nd June 2007, 07:29

Quote: (Originally Posted by silent running)

One failed, 2 current limited from same batch... The mere idea that this had anything to do with a clerical/stocking error or a manufacturing flaw makes my f****** blood boil. What the f*** do O2 cell manufacturers think people are doing with them, using them as paper weights?

I dont know if they were same batch or what cells age were - maybe Steve knows, ill ask Craig.

Added: cells were same batch but over a year old, had been working fine up to the dive

Drmike · 22nd June 2007, 07:35

Quote: (Originally Posted by dave t)

I Know Mike is going to shout at me again but

ahh come on you know you like it :you little minx

Quote:

the important thing to understand is cells are CRAP! new or old and they should not be trusted.

Aint that the truth

Quote:

What is MOST IMPORTANT is every diver learns to check his cells in as many ways as possible on EVERY dive. This "I just love to check my milivolt output to ensure my cells are good" is just bullshit

Fully agree Dave (see no shouting)

dave t · 22nd June 2007, 07:58

Quote: (Originally Posted by DeepBlueInnovation)

OK, all these statements are well and good, but will someone provide a reason why these things occur.

Dave I appreciate you listing the problems you have had with cells, but what I would appreciate even more is an explanation of why these things occur, based on rational analysis.

Why does a cell fail after three weeks?
Why does a cell fail after four months during a one hour dive?

The short answer to that is I dont know! the long answer is the manufacturing technology is not good enough, the quality control is not good enough, the original design is not suitable for the environment we use them in and some diver are not educated properly in the all the ways to manage their cells and properly understand how to check and spot impending failures

There are two opinions on cell management change all three at once within twelve months or rotate them. the problem with both of these methods apart from all cells are crap anyway is that divers choose which method to use and then have blind faith that their method is good and they are protected. well without proper predive/during dive/post dive checks they are not

Dave

**DeepBlueInnovation** · 22nd June 2007, 08:01

Not having a dig at you Dave, just hoping that someone can come up with answers. I'm by no means of scientific bent, so reading voluminous reports is just not going to happen. I was hoping that someone who does know could provide some supported answers.

**RichClark** · 22nd June 2007, 08:07

Quote: (Originally Posted by DeepBlueInnovation)

Not having a dig at you Dave, just hoping that someone can come up with answers. I'm by no means of scientific bent, so reading voluminous reports is just not going to happen. I was hoping that someone who does know could provide some supported answers.

Personally i think the bottom line is that cells aren't designed to be used in the way we use them. Because of this their failure rate etc.. is unpredictable. The only mitigation to check your cells before, during and after dives...

Thats why I only change my cells when I see some kind of imminent failure. Despite this, I still don't trust my cells. They can and will fail at any time.

Cheers

Rich

PS -

John, two words - 'Cell checker'

kieranu · 22nd June 2007, 08:16

Quote: (Originally Posted by RichClark)

PS -

John, two words - 'Cell checker'

Just need to try to convince people to put them on their boats, otherwise I suspect its going to be another very expensive toy to carry around

**RichClark** · 22nd June 2007, 08:20

Quote: (Originally Posted by kieranu)

Just need to try to convince people to put them on their boats, otherwise I suspect its going to be another very expensive toy to carry around

I'm nor sure I'd check my cells on the boat. I like to check and prep my unit at home - I only do a quick neg and re-varify my calibration on the boat before splashing.

Cheers

Rich

kieranu · 22nd June 2007, 08:28

Quote: (Originally Posted by RichClark)

I'm nor sure I'd check my cells on the boat. I like to check and prep my unit at home - I only do a quick neg and re-varify my calibration on the boat before splashing.

Cheers

Rich

Agreed - and I'm not sure how the cell checker is being designed to push the PPO2 of the cell ...

but if you're doing multiple dives / multi-day diving then that would most likely bring you back to having to do in-water current-limit testing again anyway and its likely to be an expensive piece of equipment to be used purely as a substitute for doing a ~6m check on your first dive

22nd June 2007, 07:23	#11 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 654	Re: Cell replacement policy. I Know Mike is going to shout at me again but..........I dont think it makes any difference whether you change all three at once or rotate them from different batches and different ages, the important thing to understand is cells are CRAP! new or old and they should not be trusted. I have seen them fail after three weeks, after six months and also last two years, I have seen them fail slowly and seen them die rapidly. I just had one cell that performed flawlessly for four months just die within one hour long dive. What is MOST IMPORTANT is every diver learns to check his cells in as many ways as possible on EVERY dive. This "I just love to check my milivolt output to ensure my cells are good" is just bullshit Dave
(Online)

22nd June 2007, 07:29	#12 (permalink)
DeepBlueInnovation Between Breathers Current Rebreather/s: Not Bought Yet Other Rebreather/s: Prism Topaz Not Bought Yet Join Date: Sep 2005 Location: Perth, Western Australia Posts: 353	Re: Cell replacement policy. OK, all these statements are well and good, but will someone provide a reason why these things occur. Dave I appreciate you listing the problems you have had with cells, but what I would appreciate even more is an explanation of why these things occur, based on rational analysis. Why does a cell fail after three weeks? Why does a cell fail after four months during a one hour dive?
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22nd June 2007, 07:29	#13 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,157	Re: Cell replacement policy. Quote: (Originally Posted by silent running) One failed, 2 current limited from same batch... The mere idea that this had anything to do with a clerical/stocking error or a manufacturing flaw makes my f**** blood boil. What the f* do O2 cell manufacturers think people are doing with them, using them as paper weights? I dont know if they were same batch or what cells age were - maybe Steve knows, ill ask Craig. Added: cells were same batch but over a year old, had been working fine up to the dive __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 22nd June 2007 at 07:43.
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22nd June 2007, 07:35	#14 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,157	Re: Cell replacement policy. Quote: (Originally Posted by dave t) I Know Mike is going to shout at me again but ahh come on you know you like it :you little minx Quote: the important thing to understand is cells are CRAP! new or old and they should not be trusted. Aint that the truth Quote: What is MOST IMPORTANT is every diver learns to check his cells in as many ways as possible on EVERY dive. This "I just love to check my milivolt output to ensure my cells are good" is just bullshit Fully agree Dave (see no shouting) __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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22nd June 2007, 07:58	#15 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 654	Re: Cell replacement policy. Quote: (Originally Posted by DeepBlueInnovation) OK, all these statements are well and good, but will someone provide a reason why these things occur. Dave I appreciate you listing the problems you have had with cells, but what I would appreciate even more is an explanation of why these things occur, based on rational analysis. Why does a cell fail after three weeks? Why does a cell fail after four months during a one hour dive? The short answer to that is I dont know! the long answer is the manufacturing technology is not good enough, the quality control is not good enough, the original design is not suitable for the environment we use them in and some diver are not educated properly in the all the ways to manage their cells and properly understand how to check and spot impending failures There are two opinions on cell management change all three at once within twelve months or rotate them. the problem with both of these methods apart from all cells are crap anyway is that divers choose which method to use and then have blind faith that their method is good and they are protected. well without proper predive/during dive/post dive checks they are not Dave
(Online)

22nd June 2007, 08:01	#16 (permalink)
DeepBlueInnovation Between Breathers Current Rebreather/s: Not Bought Yet Other Rebreather/s: Prism Topaz Not Bought Yet Join Date: Sep 2005 Location: Perth, Western Australia Posts: 353	Re: Cell replacement policy. Not having a dig at you Dave, just hoping that someone can come up with answers. I'm by no means of scientific bent, so reading voluminous reports is just not going to happen. I was hoping that someone who does know could provide some supported answers.
(Offline)

22nd June 2007, 08:07	#17 (permalink)
RichClark Classic KISS No. 226 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Hove, UK Posts: 772	Re: Cell replacement policy. Quote: (Originally Posted by DeepBlueInnovation) Not having a dig at you Dave, just hoping that someone can come up with answers. I'm by no means of scientific bent, so reading voluminous reports is just not going to happen. I was hoping that someone who does know could provide some supported answers. Personally i think the bottom line is that cells aren't designed to be used in the way we use them. Because of this their failure rate etc.. is unpredictable. The only mitigation to check your cells before, during and after dives... Thats why I only change my cells when I see some kind of imminent failure. Despite this, I still don't trust my cells. They can and will fail at any time. Cheers Rich PS - John, two words - 'Cell checker' __________________ The more I learn about women, the more I want to go diving... just don't tell my wife I said that To taste something a little different, try http://www.thechillikitchen.co.uk
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22nd June 2007, 08:16	#18 (permalink)
kieranu Apprentice Meg Pilot Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: WA, Australia Posts: 236	Re: Cell replacement policy. Quote: (Originally Posted by RichClark) PS - John, two words - 'Cell checker' Just need to try to convince people to put them on their boats, otherwise I suspect its going to be another very expensive toy to carry around
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22nd June 2007, 08:20	#19 (permalink)
RichClark Classic KISS No. 226 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Hove, UK Posts: 772	Re: Cell replacement policy. Quote: (Originally Posted by kieranu) Just need to try to convince people to put them on their boats, otherwise I suspect its going to be another very expensive toy to carry around I'm nor sure I'd check my cells on the boat. I like to check and prep my unit at home - I only do a quick neg and re-varify my calibration on the boat before splashing. Cheers Rich __________________ The more I learn about women, the more I want to go diving... just don't tell my wife I said that To taste something a little different, try http://www.thechillikitchen.co.uk
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22nd June 2007, 08:28	#20 (permalink)
kieranu Apprentice Meg Pilot Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: WA, Australia Posts: 236	Re: Cell replacement policy. Quote: (Originally Posted by RichClark) I'm nor sure I'd check my cells on the boat. I like to check and prep my unit at home - I only do a quick neg and re-varify my calibration on the boat before splashing. Cheers Rich Agreed - and I'm not sure how the cell checker is being designed to push the PPO2 of the cell ... but if you're doing multiple dives / multi-day diving then that would most likely bring you back to having to do in-water current-limit testing again anyway and its likely to be an expensive piece of equipment to be used purely as a substitute for doing a ~6m check on your first dive
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