MV reading on cell

dave burke · 18th January 2008, 11:38

May a a stupid question to ask and it may have already been ask
( if so then i am sorry)
just replace my old cells ( 13 months old)
old cell MV reading 10.4, 10.2, 10.2 ( old cell date all j6)
new cell reading 8.5, 9.4, 9.2
the new cells date f7,i7.i7
i have look in the AP manual it says cell MV between 8,13.5
i know that they are with in range , and dived with them yesterday , they were no faster or slower then the old cells that i have replaced
what i would like to know is should i send these cells back or keep them, then after 6 months change them one at a time starting with the one with the lowest MV reading first
any help would be appreciated
safe diving
dave

Gilles · 18th January 2008, 22:56

For one, be ready for crap cells. Teledyne, AI, they are all crap

. I've trashed many cells.

If you're not going to get yourself a cell checker, you can first;

check the mV linearity on the bench (air to PO2 = .98)

in this case the high PO2 mV = AIRmv x RICH_FO2mv/0.209

If the mV'ge is at or higher than the above theoretical value, then you can leave them in the breather for now. I'll tolerate 1 or 2 mV below theoretical if the in-water spike check of the previous dive was ok.

Next in water check, there's many ways to do this. On the way down you can manually add O2 to purposely spike your cells.

I usually just check on bottom using a rich offboard diluent (PO2 ~1.4), and then again at 4-6m at end of dive.

Hope this helps.

dave burke · 19th January 2008, 01:37

thank you for your reply
i do have a voltage meter, this is the only way
i know that you can check the MV on a cell,
if there is another meter that you can buy that checks the voltage, i did not know this.
i do spike o2 at 6M and all cells read 1.6
way i was asking about MV because when checking MV on old cells they were all at a higher voltage then the new one's
i have been told that cells start low , eg 8MV when the MV start's to get higher 10 to 13.5
that's the cells way of telling you that they are at the end of there life.
this info. to me did not seem right .
cell reading is not the problem, they will all 3 read well above the set point of 1.3
once again thanks for your reply
yes it will help
safe diving
dave

**Dsix36** · 19th January 2008, 01:49

according to my checklist:
the MV (in air) should be at least 9.0mv, replacement is indicated if lower than this.

Gilles · 19th January 2008, 09:10

Quote: (Originally Posted by dave burke)

thank you for your reply
i do have a voltage meter, this is the only way
i know that you can check the MV on a cell,
if there is another meter that you can buy that checks the voltage, i did not know this.

The Meg has a built in MV on the handsets. This is one part of good Rebreather design. Your life checking cells is much harder than mine.

Quote:

i have been told that cells start low , eg 8MV when the MV start's to get higher 10 to 13.5
that's the cells way of telling you that they are at the end of there life.
this info. to me did not seem right .

I would trust your instinct on that. I know I would call

.

What matters is the cell linearity to the SP you want to use. Most people (with built in mV meters) can at least check to PO2 = 1.0. (and then in water check)

Quote: (Originally Posted by Dsix36)

according to my checklist:
the MV (in air) should be at least 9.0mv, replacement is indicated if lower than this.

I've had a few exceptions to the following...

The cells I've had at 8.0-9.0 in air tended to last longer and be more reliable. Below 8, some remained linear but were getting slow. Cells binned at less than 9.0 are likely cells wasted.

Just my experience from a bag of 17 cells (collected over 3 years).

dave t · 19th January 2008, 15:17

As far as AP will be concerned these cells are within spec and as someone else said lower Mv cells tend to be more stable and last longer than high Mv ones. However I would keep an eye on the 8.5 one but as they are all new you may find in a week or two the Mv creeps up a bit.

If you have any doubts talk to the people yopu bought them from

HTH

Dave

dave burke · 21st January 2008, 00:18

thank you for all your replys
i have spoke to the people that i got the cells from
they have said that they are all in range,
but i will check them each time before i go diving
once again thank you for all your help
safe diving
dave

jiseson · 21st January 2008, 11:46

informative test-not focusd on the results-but rather other info contained-things to unnderstand better regarding cell handing and performance during their life span.

"Oxygen Cells for Dive Applications: Sourcing, Performance, Safety and Reliability - Results of a 6 Year Study" DV_O2_cell_study_070329.pdf

jiseson · 21st January 2008, 11:50

Quote: (Originally Posted by Gilles)

The Meg has a built in MV on the handsets. This is one part of good Rebreather design. Your life checking cells is much harder than mine.

I would trust your instinct on that. I know I would call

.

What matters is the cell linearity to the SP you want to use. Most people (with built in mV meters) can at least check to PO2 = 1.0. (and then in water check)

I've had a few exceptions to the following...

The cells I've had at 8.0-9.0 in air tended to last longer and be more reliable. Below 8, some remained linear but were getting slow. Cells binned at less than 9.0 are likely cells wasted.

Just my experience from a bag of 17 cells (collected over 3 years).

Optima has MV readouts too...

dave t · 21st January 2008, 12:07

Quote: (Originally Posted by Gilles)

What matters is the cell linearity to the SP you want to use. Most people (with built in mV meters) can at least check to PO2 = 1.0. (and then in water check).

Can you explain how you do that please? and why it can only be done if you have a MV display?

thanks

Dave

18th January 2008, 11:38	#1 (permalink)
dave burke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Dec 2006 Location: kent Posts: 119	MV reading on cell May a a stupid question to ask and it may have already been ask ( if so then i am sorry) just replace my old cells ( 13 months old) old cell MV reading 10.4, 10.2, 10.2 ( old cell date all j6) new cell reading 8.5, 9.4, 9.2 the new cells date f7,i7.i7 i have look in the AP manual it says cell MV between 8,13.5 i know that they are with in range , and dived with them yesterday , they were no faster or slower then the old cells that i have replaced what i would like to know is should i send these cells back or keep them, then after 6 months change them one at a time starting with the one with the lowest MV reading first any help would be appreciated safe diving dave
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18th January 2008, 22:56	#2 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 761	Re: MV reading on cell For one, be ready for crap cells. Teledyne, AI, they are all crap. I've trashed many cells. If you're not going to get yourself a cell checker, you can first; check the mV linearity on the bench (air to PO2 = .98) in this case the high PO2 mV = AIRmv x RICH_FO2mv/0.209 If the mV'ge is at or higher than the above theoretical value, then you can leave them in the breather for now. I'll tolerate 1 or 2 mV below theoretical if the in-water spike check of the previous dive was ok. Next in water check, there's many ways to do this. On the way down you can manually add O2 to purposely spike your cells. I usually just check on bottom using a rich offboard diluent (PO2 ~1.4), and then again at 4-6m at end of dive. Hope this helps. __________________ Gilles http://www.dirrebreather.com
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19th January 2008, 01:37	#3 (permalink)
dave burke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Dec 2006 Location: kent Posts: 119	Re: MV reading on cell thank you for your reply i do have a voltage meter, this is the only way i know that you can check the MV on a cell, if there is another meter that you can buy that checks the voltage, i did not know this. i do spike o2 at 6M and all cells read 1.6 way i was asking about MV because when checking MV on old cells they were all at a higher voltage then the new one's i have been told that cells start low , eg 8MV when the MV start's to get higher 10 to 13.5 that's the cells way of telling you that they are at the end of there life. this info. to me did not seem right . cell reading is not the problem, they will all 3 read well above the set point of 1.3 once again thanks for your reply yes it will help safe diving dave Last edited by dave burke : 19th January 2008 at 01:51.
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19th January 2008, 01:49	#4 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 891	Re: MV reading on cell according to my checklist: the MV (in air) should be at least 9.0mv, replacement is indicated if lower than this. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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19th January 2008, 09:10	#5 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 761	Re: MV reading on cell Quote: (Originally Posted by dave burke) thank you for your reply i do have a voltage meter, this is the only way i know that you can check the MV on a cell, if there is another meter that you can buy that checks the voltage, i did not know this. The Meg has a built in MV on the handsets. This is one part of good Rebreather design. Your life checking cells is much harder than mine. Quote: i have been told that cells start low , eg 8MV when the MV start's to get higher 10 to 13.5 that's the cells way of telling you that they are at the end of there life. this info. to me did not seem right . I would trust your instinct on that. I know I would call. What matters is the cell linearity to the SP you want to use. Most people (with built in mV meters) can at least check to PO2 = 1.0. (and then in water check) Quote: (Originally Posted by Dsix36) according to my checklist: the MV (in air) should be at least 9.0mv, replacement is indicated if lower than this. I've had a few exceptions to the following... The cells I've had at 8.0-9.0 in air tended to last longer and be more reliable. Below 8, some remained linear but were getting slow. Cells binned at less than 9.0 are likely cells wasted. Just my experience from a bag of 17 cells (collected over 3 years). __________________ Gilles http://www.dirrebreather.com
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19th January 2008, 15:17	#6 (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: 621	Re: MV reading on cell As far as AP will be concerned these cells are within spec and as someone else said lower Mv cells tend to be more stable and last longer than high Mv ones. However I would keep an eye on the 8.5 one but as they are all new you may find in a week or two the Mv creeps up a bit. If you have any doubts talk to the people yopu bought them from HTH Dave
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21st January 2008, 00:18	#7 (permalink)
dave burke Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Dec 2006 Location: kent Posts: 119	Re: MV reading on cell thank you for all your replys i have spoke to the people that i got the cells from they have said that they are all in range, but i will check them each time before i go diving once again thank you for all your help safe diving dave
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21st January 2008, 11:46	#8 (permalink)
jiseson DSIX/O2PTIMA Current Rebreather/s: Optima Other Rebreather/s: Join Date: Jun 2006 Location: long island,ny Posts: 454	Re: MV reading on cell informative test-not focusd on the results-but rather other info contained-things to unnderstand better regarding cell handing and performance during their life span. "Oxygen Cells for Dive Applications: Sourcing, Performance, Safety and Reliability - Results of a 6 Year Study" DV_O2_cell_study_070329.pdf __________________ *Jonathan D Iseson*
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21st January 2008, 11:50	#9 (permalink)
jiseson DSIX/O2PTIMA Current Rebreather/s: Optima Other Rebreather/s: Join Date: Jun 2006 Location: long island,ny Posts: 454	Re: MV reading on cell Quote: (Originally Posted by Gilles) The Meg has a built in MV on the handsets. This is one part of good Rebreather design. Your life checking cells is much harder than mine. I would trust your instinct on that. I know I would call. What matters is the cell linearity to the SP you want to use. Most people (with built in mV meters) can at least check to PO2 = 1.0. (and then in water check) I've had a few exceptions to the following... The cells I've had at 8.0-9.0 in air tended to last longer and be more reliable. Below 8, some remained linear but were getting slow. Cells binned at less than 9.0 are likely cells wasted. Just my experience from a bag of 17 cells (collected over 3 years). Optima has MV readouts too... __________________ *Jonathan D Iseson*
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21st January 2008, 12:07	#10 (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: 621	Re: MV reading on cell Quote: (Originally Posted by Gilles) What matters is the cell linearity to the SP you want to use. Most people (with built in mV meters) can at least check to PO2 = 1.0. (and then in water check). Can you explain how you do that please? and why it can only be done if you have a MV display? thanks Dave
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