O2 Cell Replacement Time....

[taimen]

Does anyone have any experience with german nrc-international cells?
Their cell for JJ-CCR can be had with 69€.

 

[rddvet]

That’s the problem though, it’s not like there’s a cycle of “bad batch timelines” that you can get on. The whole idea of a bad batch is that it’s random and unpredictable. We’re they more common in the past? I’m not sure that’s the case. Is QC better now? Maybe. But people still get E. Coli.

Tom brings up another good point re:cell age and failure. It’s certainly another consideration.

I think the point is that there's a lot of stories that people "heard from a friend or instructor" but when you start looking into it, bad batches just aren't a reality. It's more of an "urban legend" for lack of better words. I'm a very new rb diver, so I don't know the answer. I do know that I've asked people that no one can actually give me a true first hand account of bad batches. Obviously single bad cells are a thing, but whole runs or batches I don't know. My instrcuto's group of friends who have much more experience than me tend to think it's not a reality.

My instructor told me that the stock JJ Vandegraph were more reliable than the AI sensors. I guess I forgot his advice the first time I changed the sensors and bought AI. Can't remember the exact issues, but I remember them being much less stable and slower to react than the Vandegraphs. Bought Vandegraphs again, all went back to normal.

Just one anecdote, take it for whatever it's worth.

I was told that the vandegraph are better but that in the grand scheme of things AI are good enough. Y unit uses the same as a jj

 

[JohnnyC]

I know that APD had a particularly bad batch, a friend of mine had an Inspo and dealt with all that but that was several years ago. I’m not sure how widespread it is, but for very little hardship it’s easy to hedge bets against. I’ve never worried about it because I never buy a full set of cells at a time.

The Vandegraph cells are better than the AI’s, visibly so in terms of response time, but I’m not sure that it’s much of a difference in other regards.

 

[michael-fisch]

Does anyone have any experience with german nrc-international cells?
Their cell for JJ-CCR can be had with 69€.

Tried them and they were the worst cells I ever bought.
After 3 months my cell tester had determined that all 3 were no longer linear above 90% PPO2. Great for a cheap O2 analyser to be used on Nitrox 32 but useless for rebreathers running 1.3 PPO2 aund decoing at 1.6 PPO2. Switched back to AI PSR11-39-MD3 and PSR11-39-XD cells which I religiously change 19 months after date of manufacture. Then they can still be used for another year in O2 analysers up to 1.0 PPO2.

Germans are still incapable of making a good sensor cell, and that means NRC ! If you want the best buy Vandergraph, almost as good is Analytical Industries, anything else should only be used to decorate the garbage bag.


Michael
Who just put a new set of AI Cells in his XCCR, FLEX and SF2 rebreathers.

BTW if you are buying 9-10 cells every 18 months you can expect a discount from whoever sells them to you, it doesn't hurt to ask.

 

[v101]

I do a linear test each time I dive my unit. That way I know how linear my cells are. When they get down to a certain Mv level or percent linear, I change them out. Typically i only replace 1 cell at a time, before it goes bad, and keep the previously used one in my save a dive kit. This way its not costing me replacing 3 cells a time. My cells typically last a good 15 months, before they start getting swapped out.

 

[tomfcrist]

Replace one cell every 6 months, this what I do in my rEvo which has 5 cells.

So you have cells in your unit that are 2 years old?

 

[davehicks]

I suggest rotating cells. Always have a couple of spare on hand and replace them as they start to read low mV compared to the rest. In my 11 years of rebreather diving I've found a lot of variation cell to cell even with good reliable brands in the same batch. Some will last for 2 years, others for 6 months. Rotate and replace as needed. Order more spares when you use the last one.

 

[rjack321]

Get the vandergraphs

 

[Superlyte27]

I think the point is that there's a lot of stories that people "heard from a friend or instructor" but when you start looking into it, bad batches just aren't a reality. It's more of an "urban legend" for lack of better words. I'm a very new rb diver, so I don't know the answer. I do know that I've asked people that no one can actually give me a true first hand account of bad batches. Obviously single bad cells are a thing, but whole runs or batches I don't know. My instrcuto's group of friends who have much more experience than me tend to think it's not a reality.



I was told that the vandegraph are better but that in the grand scheme of things AI are good enough. Y unit uses the same as a jj

I can give you two first hand accounts...
I was part of a massive Maxtec 305 recall. If you’ll look, you’ll notice Maxtec 305 was replaced with a new model, I think it’s 305F now or something like that.

Also, early on, I got a bad batch of AI’s, but that was a fluke. I certainly don’t think it’s the norm.

Today, at least a few manufacturers are stating that you should replace all sensors at once. I talked to Dive Soft recently regarding the Liberty. Because that machine is so precise, (as I understand it) it wants to calibrate cells that are exactly the same. Apparently there are very minor variances in cells prior to calibration. My optima doesn’t care. It’ll take a very broad array of cells and work seamlessly, but if I put three different cells in a Liberty, it freaks out on the dive, voting out dissimilar cells constantly.

When I took rEvo class, Paul Raemakers said to spread out cell replacement. Recent classes have told me to buy all in the same batch. I think that bad batches are rare, and we test for cell linearity before and during a dive. We have protocols to ensure our wellbeing and I’m not afraid of a bad batch of cells. But I do think it’s unlikely but possible.

 

[tbone1004]

So you have cells in your unit that are 2 years old?

if they are not limited and are within acceptable limits of linearity, why would you replace them? It is known to be stable, so why replace?