Current State Of Rebreather Electronics

[silent running]

The XCCR has two 1 atm compartments for 18650 batteries. They are outside of the loop also. It’s plenty of power for electronics, a solenoid and electronic sensors.

I should hope they are outside the loop, that is a must in my book for many reasons.

See the above link posted by njdiverjoe for the power necessary per sensor, then double that, add all the other stuff and I don’t think 2 18650’s will have enough of a safety margin.

Obviously we will have to wait and see what battery arrangement Poseidon comes up for their next generation all sss CCR, but it will probably be the largest battery in any CCR to date.

 

[RainPilot]

No, it won't. It will be exactly the same as the present setup.

The current battery in the Poseidon is an 18650, sealed into a battery canister that also contains a backup computer and buddy LED light. That battery gives 40-60 hours of dive time from a full charge.

The SSS in a 3rd cell config takes power from the M28 computers that reads it. I get around 25-30 hours off a single charge on the computer, according to the lead diver at Poseidon, the SSS will reduce that runtime but so far he hasn't noticed any significant change (still recharging the computer every couple of days, or before a big dive)

He runs one M28 and SSS, and another M28 to control the CCR, he hasn't seen any significant differences in the battery runtimes between them.

I am getting my SSS and 3rd cell pod in 2 weeks, I will give feedback to those who are interested.

Right now, I expect that the runtime on a Poseidon Seven with dual SSS (which they do not recommend right now for other reasons) and the existing battery config will go from 40-60 hours, down to 30-50 hours. Again, I have never lost a dive due to battery low and I have done 3 day liveaboards with 3 x 1.5hr plus dives a day and ended the trip with well over half the battery life remaining. This with not turning the unit off between dives, except when I have to change scrubber.

If you are using an M28 as controller, it can also power the whole unit should the onboard battery fail, via the digital bus.

 

[Jeremy Williams]

I should hope they are outside the loop, that is a must in my book for many reasons

I realize now that my word choice wasn’t good. Any 1 atm compartment is by-definition outside of the loop. My meaning was that it’s heavily isolated from the ambient chamber and placed on the outside of the head.

I suppose we shall see... eventually. It’s taken Poseidon a long time to seemingly get this to market. It’s been available on paper for a couple of years, right? I’m all for anything that advances the art of diving.

 

[silent running]

No, it won't. It will be exactly the same as the present setup.

The current battery in the Poseidon is an 18650, sealed into a battery canister that also contains a backup computer and buddy LED light. That battery gives 40-60 hours of dive time from a full charge.

The SSS in a 3rd cell config takes power from the M28 computers that reads it. I get around 25-30 hours off a single charge on the computer, according to the lead diver at Poseidon, the SSS will reduce that runtime but so far he hasn't noticed any significant change (still recharging the computer every couple of days, or before a big dive)

He runs one M28 and SSS, and another M28 to control the CCR, he hasn't seen any significant differences in the battery runtimes between them.

I am getting my SSS and 3rd cell pod in 2 weeks, I will give feedback to those who are interested.

Right now, I expect that the runtime on a Poseidon Seven with dual SSS (which they do not recommend right now for other reasons) and the existing battery config will go from 40-60 hours, down to 30-50 hours. Again, I have never lost a dive due to battery low and I have done 3 day liveaboards with 3 x 1.5hr plus dives a day and ended the trip with well over half the battery life remaining. This with not turning the unit off between dives, except when I have to change scrubber.

If you are using an M28 as controller, it can also power the whole unit should the onboard battery fail, via the digital bus.

I’m glad you’ve had good luck with batteries, many of us have not. 25-30 hours being reduced by one sss, but by how much? Where is your personal safety threshold? In my experience batteries fall off exponentially as you get closer to their claimed limits. It’s good that the unit has back up batteries, which is a must in any fly by wire system, but then you need a battery management subsystem in the computer, which is another opportunity for a coding mistake. Complexity begets more complexity, no free lunch. It was stated elsewhere in this thread perhaps by you, that Poseidon has borrowed some fly by wire technology from aviation. That’s good, but I find it hard to believe Poseidon has the resources to test their systems to the degree that aviation does. Call me paranoid, but I just can’t imagine ever feeling comfortable with a totally dive by wire system until a lot more validation is done of these increasingly complex electronics, now featuring sss.

There is more than one type of battery failure. Does the MK7 still have corrosion issues with the battery terminals?

Also, what is the other reason Poseidon do not currently recommend using dual sss?

 

[silent running]

I realize now that my word choice wasn’t good. Any 1 atm compartment is by-definition outside of the loop. My meaning was that it’s heavily isolated from the ambient chamber and placed on the outside of the head.

I suppose we shall see... eventually. It’s taken Poseidon a long time to seemingly get this to market. It’s been available on paper for a couple of years, right? I’m all for anything that advances the art of diving.

FWIW, I wasn’t actually giving you a hard time about your word choice, I was referring to older bad designs by some manufacturers which placed batteries inside the loop as a way to avoid 1ATA compartments...

 

[Jeremy Williams]

[QUOTE="silent running, post: 8765217, member: 24468] I was referring to older bad designs by some manufacturers which placed batteries inside the loop as a way to avoid 1ATA compartments...[/QUOTE]

I agree then. That’s just not good at all. Too many new toxins in the loop at that point.

 

[АлександрД]

Is anybody know AV1 (AV1f) computer | AV Underwater Technologies systems? It has Fisher connector...
This system also have hud Heads-up display HUD-AF | AV Underwater Technologies and thermal stick for scrubber Temperature scrubber sensor (TSS) | AV Underwater Technologies
I`m not a rebreather diver (just try it), but heard good responses about AV-1 from friends..
may be this information could be interesting for somebody.
Also you can contact with designer/manufacturer directly https://www.facebook.com/profile.php?id=100008667018124

 

[JohnnyC]

Lots of people use AV1 stuff to replace obsolete electronics, Inspo heads, etc. I hear good things about Alexey and his gear, I just don't have a need for it.

The fischer-only HUD is pretty slick. You can add a HUD to anything that has a fischer cable, which is pretty snazzy if you're in to HUD's. My understanding is that it's pretty obnoxious, which depending on what side of the argument you sit on, is either a good thing or a bad thing. I haven't dived a HUD since my Meg because it's next to useless, not bright where it counts, takes too long to glean reasonable data, etc. The AV1 HUD is a fundamentally different design. Maybe I'll give one a try some day.

 

[RainPilot]

25-30 hours being reduced by one sss, but by how much? Where is your personal safety threshold?

Well, a dive computer that gives 25-30 hours between charges is pretty good. If the SSS drops that by 50% (much more than observed by users so far) then I would have 12-15 hours between charges. Thats enough for a couple of days of the dives I do, or i can recharge it overnight and do whatever dive I may want to. The charge percentage and remaining battery life is very well calibrated and shown, just like on SW computers etc.

Does the MK7 still have corrosion issues with the battery terminals?

Those are due to people removing the batteries while the units are still wet and allowing water to run into the connector. Same as people getting 1st stage issues from allowing salt to get into the inlet etc etc.

Also, what is the other reason Poseidon do not currently recommend using dual sss?

One of the big reasons is about the concept of "independent" sensors, which we do not actually have with dual or more galvanic sensors (watch this for some background on the Poseidon cell philosophy
Short version, if you have two cells with same mechanism, they cannot be truly "independent" since they are exposed to the same conditions. If you have one SSS and one galvanic as a backup, you have a genuinely independent , redundant system.

 

[stuartv]

One of the big reasons is about the concept of "independent" sensors, which we do not actually have with dual or more galvanic sensors (watch this for some background on the Poseidon cell philosophy
Short version, if you have two cells with same mechanism, they cannot be truly "independent" since they are exposed to the same conditions. If you have one SSS and one galvanic as a backup, you have a genuinely independent , redundant system.

Well, that was a big honkin’ load of Kool-Aid.

Yes, I watched the whole video. Yes, I majored in Mathematics and Logic & Computability in college.

I well give the presenter a kudo, though. He had enough integrity to say in his Summary that 3 sensors in a voting configuration are better than a single sensor. He just said it in such a way as to absolutely minimize the real superiority of the 3 sensor voting configuration.

He said “unless very careful steps are taken, three ... are little better than a single sensor.” He totally redirects from considering how much better 3 are when you ARE very careful. At least he acknowledges that even if you are not very careful 3 are still a little better than a single sensor.