Changing cells

Mephisto26 · 30th September 2007, 05:13

Hey All,

I have two still ok cells but on the lower end will have to change them in a few months (maybe2) and one thats done...do you change all at the same time or better to only change the one...

Thanks for input

Patrick

Gilles · 30th September 2007, 05:45

Hi Patrick;

I suggest only changing the cells that are down, and keeping randomly aged/worn cells in. This increases the liklihood that only 1 cell fails at a time.

The disadvantage of this is that there is a somewhat increased liklihood of at least 1 cell failure (and thus the need to turn the dive).

Grounded due to bad weather

G

Mephisto26 · 30th September 2007, 16:23

Hey Gilles,

I thought about that but my concern is the voting logic...having two older cells and one new cell...

What do you think???

**wedivebc** · 30th September 2007, 20:28

Quote: (Originally Posted by Gilles)

Hi Patrick;

I suggest only changing the cells that are down, and keeping randomly aged/worn cells in. This increases the liklihood that only 1 cell fails at a time.

The disadvantage of this is that there is a somewhat increased liklihood of at least 1 cell failure (and thus the need to turn the dive).

Grounded due to bad weather

G

Teledyne insured my random cell change routine by have so many fail when my Rebreather was new. Now I just replace when they don't pass low and high pressure checks.

***ScubaDadMiami*** · 30th September 2007, 20:33

I am a good boy and change my cells annually. The first year, I change one on month 10, one on month 11, and one on month 12. After that, I change on the anniversary of each.

This gives me a chance to test each replacement cell against two others that are known.

**Dsix36** · 30th September 2007, 21:24

I only have about 20 hours on my unit and have just recently finished training, so take this for what it is worth

I have had to replace 2 of my sensors already. 1 week (1 dive) apart from each other. I caught both of them by the assembly and post-assembly checklists. 9mv+/40mv+ that I was trained with. I was able to see the change in mv readings from dive to dive by referring to my recorded reading and replaced them prior to diving the unit.

IMHO I believe that sensor failure can be predicted by the change in mv readings over time. If one sensor is declining much faster than another-it will fail sooner.

Now, back to the issue at hand. I prefer to change the sensors at different times to prevent a failure issue like I had. If I was doing a 4hr dive, I would have lost 2 senors on the same dive and had problems.

I was told (by my instructor) not to use sensors from the same manufacturing "run". If 1 is weak, all are probably weak, and that this was my sensor problem.

I will change my sensors every year, with a 1 month difference (like Howard said).

Gilles · 30th September 2007, 22:46

Quote: (Originally Posted by Mephisto26)

Hey Gilles,

I thought about that but my concern is the voting logic...having two older cells and one new cell...

What do you think???

As indicated above, whether new or not, there's a substantial possibility they will start failing anyway.

IMHO the most practical thing (short of acquirng a cell pot) is first check the mV linearities to 1.0, gear up n go in, and check that they reach 1.4-1.6 @ 4-6m. Check again that they reach 1.4-1.6 at end of dive (@4-6m).

Mephisto26 · 1st October 2007, 00:00

Thanks as always for your quick replies...

Dive SAFE

Patricio

Rickoz · 6th October 2007, 21:34

Quote: (Originally Posted by Dsix36)

I only have about 20 hours on my unit and have just recently finished training, so take this for what it is worth

I have had to replace 2 of my sensors already. 1 week (1 dive) apart from each other. I caught both of them by the assembly and post-assembly checklists. 9mv+/40mv+ that I was trained with. I was able to see the change in mv readings from dive to dive by referring to my recorded reading and replaced them prior to diving the unit.

IMHO I believe that sensor failure can be predicted by the change in mv readings over time. If one sensor is declining much faster than another-it will fail sooner.

Now, back to the issue at hand. I prefer to change the sensors at different times to prevent a failure issue like I had. If I was doing a 4hr dive, I would have lost 2 senors on the same dive and had problems.

I was told (by my instructor) not to use sensors from the same manufacturing "run". If 1 is weak, all are probably weak, and that this was my sensor problem.

I will change my sensors every year, with a 1 month difference (like Howard said).

Yep sounds good to me, cut a long story short.
have 4 new sensors, go on a trip. now i have 3 failed sensors
1 before the trip 2nd on the first day of the trip 3rd on the 2nd day of the trip

Rickoz

**Dsix36** · 6th October 2007, 21:53

Hey Rickoz,

I like that Avator

30th September 2007, 05:13	#1 (permalink)
Mephisto26 New Member Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Classic Kiss Join Date: Jun 2006 Location: Playa del Carmen Q.Roo Mexico Posts: 89	Changing cells Hey All, I have two still ok cells but on the lower end will have to change them in a few months (maybe2) and one thats done...do you change all at the same time or better to only change the one... Thanks for input Patrick
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30th September 2007, 05:45	#2 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 762	Re: Changing cells Hi Patrick; I suggest only changing the cells that are down, and keeping randomly aged/worn cells in. This increases the liklihood that only 1 cell fails at a time. The disadvantage of this is that there is a somewhat increased liklihood of at least 1 cell failure (and thus the need to turn the dive). Grounded due to bad weather G __________________ Gilles http://www.dirrebreather.com
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30th September 2007, 16:23	#3 (permalink)
Mephisto26 New Member Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Classic Kiss Join Date: Jun 2006 Location: Playa del Carmen Q.Roo Mexico Posts: 89	Re: Changing cells Hey Gilles, I thought about that but my concern is the voting logic...having two older cells and one new cell... What do you think???
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30th September 2007, 20:28	#4 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,410	Re: Changing cells Quote: (Originally Posted by Gilles) Hi Patrick; I suggest only changing the cells that are down, and keeping randomly aged/worn cells in. This increases the liklihood that only 1 cell fails at a time. The disadvantage of this is that there is a somewhat increased liklihood of at least 1 cell failure (and thus the need to turn the dive). Grounded due to bad weather G Teledyne insured my random cell change routine by have so many fail when my Rebreather was new. Now I just replace when they don't pass low and high pressure checks. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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30th September 2007, 20:33	#5 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 2,068	Re: Changing cells I am a good boy and change my cells annually. The first year, I change one on month 10, one on month 11, and one on month 12. After that, I change on the anniversary of each. This gives me a chance to test each replacement cell against two others that are known. __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
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30th September 2007, 21:24	#6 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 976	Re: Changing cells I only have about 20 hours on my unit and have just recently finished training, so take this for what it is worth I have had to replace 2 of my sensors already. 1 week (1 dive) apart from each other. I caught both of them by the assembly and post-assembly checklists. 9mv+/40mv+ that I was trained with. I was able to see the change in mv readings from dive to dive by referring to my recorded reading and replaced them prior to diving the unit. IMHO I believe that sensor failure can be predicted by the change in mv readings over time. If one sensor is declining much faster than another-it will fail sooner. Now, back to the issue at hand. I prefer to change the sensors at different times to prevent a failure issue like I had. If I was doing a 4hr dive, I would have lost 2 senors on the same dive and had problems. I was told (by my instructor) not to use sensors from the same manufacturing "run". If 1 is weak, all are probably weak, and that this was my sensor problem. I will change my sensors every year, with a 1 month difference (like Howard said). __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
(Online)

30th September 2007, 22:46	#7 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 762	Re: Changing cells Quote: (Originally Posted by Mephisto26) Hey Gilles, I thought about that but my concern is the voting logic...having two older cells and one new cell... What do you think??? As indicated above, whether new or not, there's a substantial possibility they will start failing anyway. IMHO the most practical thing (short of acquirng a cell pot) is first check the mV linearities to 1.0, gear up n go in, and check that they reach 1.4-1.6 @ 4-6m. Check again that they reach 1.4-1.6 at end of dive (@4-6m). __________________ Gilles http://www.dirrebreather.com Last edited by Gilles : 30th September 2007 at 22:50.
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1st October 2007, 00:00	#8 (permalink)
Mephisto26 New Member Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Classic Kiss Join Date: Jun 2006 Location: Playa del Carmen Q.Roo Mexico Posts: 89	Re: Changing cells Thanks as always for your quick replies... Dive SAFE Patricio
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6th October 2007, 21:34	#9 (permalink)
Rickoz KISS Rebreather Pilot 109 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Feb 2005 Location: Australia Posts: 147	Re: Changing cells Quote: (Originally Posted by Dsix36) I only have about 20 hours on my unit and have just recently finished training, so take this for what it is worth I have had to replace 2 of my sensors already. 1 week (1 dive) apart from each other. I caught both of them by the assembly and post-assembly checklists. 9mv+/40mv+ that I was trained with. I was able to see the change in mv readings from dive to dive by referring to my recorded reading and replaced them prior to diving the unit. IMHO I believe that sensor failure can be predicted by the change in mv readings over time. If one sensor is declining much faster than another-it will fail sooner. Now, back to the issue at hand. I prefer to change the sensors at different times to prevent a failure issue like I had. If I was doing a 4hr dive, I would have lost 2 senors on the same dive and had problems. I was told (by my instructor) not to use sensors from the same manufacturing "run". If 1 is weak, all are probably weak, and that this was my sensor problem. I will change my sensors every year, with a 1 month difference (like Howard said). Yep sounds good to me, cut a long story short. have 4 new sensors, go on a trip. now i have 3 failed sensors 1 before the trip 2nd on the first day of the trip 3rd on the 2nd day of the trip Rickoz __________________ Rickoz KISS Rebreather Pilot 109
(Offline)

6th October 2007, 21:53	#10 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 976	Re: Changing cells Hey Rickoz, I like that Avator __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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