Mike goes through the new Dive Talk Go

[nadwidny]

I don’t understand exactly what this is for, if the al80 on your back is dil and bailout, what extra does it do for you. Is it just a shallow 02 rebreather.

Travel for one. Like the Triton. If I had a lot of tropical trips in the future I might look at this.

 

[Wibble]

That wasn't the question though. Someone ask 'why some ccrs have 4 or 5 cells'. That wasn't done so you can try SSS in the future. Having a 4th or 5th g cells I think is gimmicky... if you want a 4th port to try some new cell, that's a different topic.

You’re being disingenuous and narrow focused.

Galvanic cells are fundamentally unreliable; failing randomly. They have a limited lifespan as they’re essentially oxygen batteries, hence the commonly accepted practice to replace them annually. Even then they frequently and randomly fail within that time. They have a limited shelf life even in their manufacturer's packaging and are sensitive to heat.

There are other failure modes in the oxygen monitoring system such as wires, connectors, A2D converters, computers, controllers and batteries.

Many rebreathers use or have the option for more than 3 cells. Some use more as there’s two independent monitoring systems.

Solid state oxygen cells offer the tantalising possibility of much greater lifespans and far greater reliability. They might even be reliable enough to only require two cells. Hopefully they’ll be cheaper over the lifespan of a rebreather.

 

[RedSix]

Solid state oxygen cells offer the tantalising possibility of much greater lifespans and far greater reliability. They might even be reliable enough to only require two cells. Hopefully they’ll be cheaper over the lifespan of a rebreather.

Up to now these are assumptions, which have not been proven.
Beside these assumptions it is known, that the solid state cells are prone to a significant drift if exposed to elevated temperatures (e.g. in a car; see Optical Oxygen Sensor, solid state sensor, oxygen sensor, diving, tauchen ). And this drift needs weeks to normalize.

 

[Wibble]

Solid state oxygen cells offer the tantalising possibility of much greater lifespans and far greater reliability. They might even be reliable enough to only require two cells. Hopefully they’ll be cheaper over the lifespan of a rebreather.

Up to now these are assumptions, which have not been proved.
Beside these assumptions it is known, that the solid state cells are prone to a significant drift if exposed to elevated temperatures (e.g. in a car; see Optical Oxygen Sensor, solid state sensor, oxygen sensor, diving, tauchen ). And this drift needs weeks to normalize.

Hence using the words "Solid state oxygen cells offer the tantalising possibility of much greater lifespans and far greater reliability".

 

[berndo]

... so having the redundancy is welcome.

3 cells give you redundancy. Again, you can flush the loop to see what cell(s) are off. Having more old cells doesn't doesn't help to figure out what cell or cells are off.
According to your logic, a ten cell ccr would be even better than.
Since you brought up long cave dives... how come most people who do long cave dive run 3 cell units than? More people seem to dive JJ, Fathom, KISS, etc. in caves, not many revos. Fathom is a relatively new unit and used by people who do deep and long cave dives... why doesn't that thing use 5 cells? I'm sure the designer is aware of the revo argument. Same goes for KISS Mike and other people.

Having more reliable solid state cells would mean that number could be reduced without compromising safety.

This was my point, you don't know this. IF SSS were such a game changer, how come nobody bought a Poseidon? Why didn't you get one? You could have gotten a 'game changing' piece of tech and you stuck with a ccr for that you can't dump water from? How does that add up?
These cells could be great or not... you don't know and I don't know. The new cells are run on a little button cell... you think those can't fail or drain too fast for whatever reason?
G cells are time tested, work pretty well and seemingly haven't been the cause or contributing factor in any or many accidents (you seem to have ignored this point). Game changing tech IMHO would be something that either reduces accidents or gives an actual advantage diving... checking g cell and changing them is not a big deal and you will have to check the new cells too.

 

[jborg]

work pretty well and seemingly haven't been the cause or contributing factor in any or many accidents (you seem to have ignored this point)

I have no horse in this race, don't dive a CCR.

However, I think it's slightly disingenuous to say the cells "work pretty well" when the context that makes them do so is using at least three at any given moment and having an elaborate set of voting logic and processes to detect and ignore the non-working cells as part of everyday CCR diving. That the end result works isn't a testament to reliable cells, it's a result of the layers of redundancy and workarounds built on top to handle the fact that they are unreliable.

There was a well-publicised cell-related death a bunch of years back (two cells went bad on the same dive), but I think the consensus was that it was human factors (using way too old cells, ignoring alarms, etc) that really caused the accident.

 

[SavageSeaCow]

3 cells give you redundancy. Again, you can flush the loop to see what cell(s) are off. Having more old cells doesn't doesn't help to figure out what cell or cells are off.
According to your logic, a ten cell ccr would be even better than.
Since you brought up long cave dives... how come most people who do long cave dive run 3 cell units than? More people seem to dive JJ, Fathom, KISS, etc. in caves, not many revos. Fathom is a relatively new unit and used by people who do deep and long cave dives... why doesn't that thing use 5 cells? I'm sure the designer is aware of the revo argument. Same goes for KISS Mike and other people.


This was my point, you don't know this. IF SSS were such a game changer, how come nobody bought a Poseidon? Why didn't you get one? You could have gotten a 'game changing' piece of tech and you stuck with a ccr for that you can't dump water from? How does that add up?
These cells could be great or not... you don't know and I don't know. The new cells are run on a little button cell... you think those can't fail or drain too fast for whatever reason?
G cells are time tested, work pretty well and seemingly haven't been the cause or contributing factor in any or many accidents (you seem to have ignored this point). Game changing tech IMHO would be something that either reduces accidents or gives an actual advantage diving... checking g cell and changing them is not a big deal and you will have to check the new cells too.

Sounds like you won’t be using them. Great. Your arguments about “why other people using them?” Has nothing to do with how good or reliable the tech is. Other companies didn’t use them because of the expense and because of the risk of being first. I did think about getting a Poseidon but there were features on my rEvo that I valued more. In the end there are always trade offs but I would happily retrofit them in now. I’ve been chatting with Martin about the best way to do it actually, but if I can do it without adding a battery canister I will.

The process of keeping track of cells and calibrating them before every dive is a potential source of error that is eliminated with the new tech. The cell is on or off. Period. No concern that one is going bad during the dive, trying to sort it out while doing something else that requires your attention etc. If the little button dies, oh well. The space will read blank and you’ll know it’s dead. No guessing and flushing or trusting your life to non linear electrochemistry. You’ll have another as a back up and that extra one will be enough. No worries about whether the calibration was good/right and whether it’s going to cause you to get bent or toxed.

With regards to the cell redundancy issue, yes you can flush and know your cell is ******, but that doesn’t help you calculate an accurate decompression. As far as I know shearwater still doesn’t allow you to manually out vote a cell and won’t do so automatically until it’s like 20% off. I don’t think it’s a gimmick then to have a separate accurate computer to tell you your deco obligation.

If you decide you want to let everyone else try them first and see how it goes, great. That’s what we are asking for. To have the opportunity to use a technology that has the potential to increase safety and move the sport forward. People had the same arguments about dive computers, nitrox, trimix etc. “we’ve been diving deep air on tables for decades, why would we trust helium and a dive computer?”

 

[berndo]

So you're a guy who doesn't dive a rebreather but knows better than the guys who design rebreathers... got it.

There was a well-publicised cell-related death a bunch of years back (two cells went bad on the same dive), but I think the consensus was that it was human factors (using way too old cells, ignoring alarms, etc) that really caused the accident.

Which one was that? The one where the cells were 4 years old?

 

[jborg]

Which one was that? The one where the cells were 4 years old?

Something like that.

 

[berndo]

No concern that one is going bad during the dive

Sounds pretty naiv to me.

I don’t think it’s a gimmick then to have a separate accurate computer to tell you your deco obligation.

You still haven't answered why the deep cave exploration guys don't use revos but 3 cell units than? You think they haven't read the revo marketing brochure about 'more redundancy'? If it wasn't a gimmick but actually better, other manufacturer would have adopted the 5 cells thing by now... but nobody has.