Poseidon Releases Solid State Sensors

[Rich1280]

I'm really not knowledgeable about electronics, so if anyone has any ideas I'd love to hear. How big are the SS sensors, and what is the power drain on them? Is the next iteration a plug in where the current sensor goes, and the power is a replaceable 2032 cell or the like slotted into the sensor itself? That would seem like a logical interim design progression before they are powered from the RB themselves and have different fittings.

Rich

 

[TuckerIdaho]

I guess the Tecme solution is a good option for those of us that don't want to wait until the actual rebreather manufacturers get onboard with solid state cells as it allows us to easily have a solid state cell feeding to say a Nerd2 without having to wait for the manufacturers to do their stuff etc - and remember for those manufacturers whose rebreathers are CE it will probably mean going through the CE testing again :-( - and it doesn't involve needing to send the head back to the manufacturer for modification etc. - often times quick to implement but not absolutely 100% ideal is better than having to wait 2 years for the ideal solution - which will eventually come anyway...

Yes, they will have to be modified, no you won't be able to do it yourself, yes they will have to recertify CE.

 

[tbone1004]

I'm really not knowledgeable about electronics, so if anyone has any ideas I'd love to hear. How big are the SS sensors, and what is the power drain on them? Is the next iteration a plug in where the current sensor goes, and the power is a replaceable 2032 cell or the like slotted into the sensor itself? That would seem like a logical interim design progression before they are powered from the RB themselves and have different fittings.

Rich

similar form factor to current galvanic sensors. Power consumption is pretty negligible in a modern eCCR. The batteries that power the the SOLO board in Divecan can power the units just like they power the current board that does the ADC from the galvanic cells. The external boards and batteries from Tecme are doing the opposite of what the O2 boards in DiveCAN are doing and doing DAC. Digital signal output from the sensors, converting that to an analog mV signal to mimic the dc voltage output of a galvanic cell.
Peak power consumption is 0.2w, assume unit is turned on for 6hrs for a full day of diving that's 1.2wh/dive/cell, so 2.5wh/day peak, most likely half that. Many of these units use 9v batteries for the SOLOE/Solenoid, which would be powering these. Since a 9v battery has ~5wh usable and at least with Dive Rite quotes the O2ptima 9v battery as lasting ~50hrs of dive time, I would say that you will likely find yourself replacing the 9v battery every other scrubber depending on how long you have the unit turned on before/after the dive. If you're running really long dives of 6+hrs then probably replacing every scrubber. Thankfully there are high quality rechargeable 9v's out there.

Yes, they will have to be modified, no you won't be able to do it yourself, yes they will have to recertify CE.

the middle bit is actually not necessarily true and will depend on the rebreather. The Liberty and Meg at least will be DIY as their O2 control boards are user replaceable. Most rebreathers will probably need a full head upgrade if the boards are potted into the head, but there are a couple that will be able to have DIY upgrades.

 

[makar0n]

similar form factor to current galvanic sensors. Power consumption is negligible in a modern eCCR. The batteries that power the the SOLO board in Divecan can power the units just like they power the current board that does the ADC from the galvanic cells. The external boards and batteries from Tecme are doing the opposite of what the O2 boards in DiveCAN are doing and doing DAC. Digital signal output from the sensors, converting that to an analog mV signal to mimic the dc voltage output of a galvanic cell.

Hmm interesting...so basically the existing DiveCAN power sources would be enough? Well this certainly would be great news!
Ha then just gotta remove that single conversion thingie (on O2 board), and then more or less can screw the solid state cells right into now fully digital Choppy xD

 

[tbone1004]

Hmm interesting...so basically the existing DiveCAN power sources would be enough? Well this certainly would be great news!
Ha then just gotta remove that single conversion thingie (on O2 board), and then more or less can screw the solid state cells right into now fully digital Choppy xD

I just pulled the data sheet on the sensor and the peak power consumption is higher than I thought so I edited my original post.
The unit is rated for 3.3-5v power supply and consumes 8mA at standby and 40mA peak. That's a range of 0.3wh-0.2wh in power consumption so it's somewhere in the middle since I don't have data for the real power curve. I would suspect that it's closer to 0.1wh on average during the course of a day, which puts each cell at a similar power consumption to the SOLOE board + solenoid based on Dive Rites ~50hr run time on a 9v battery, so if you're running a pair of cells, SOLOE, and Solenoid off of a 9v, then cut your run time to a third or quarter of what you're getting now. Certainly not all that offensive and if they use rechargeable batteries like the Liberty it's not that difficult to plug it in overnight.

 

[makar0n]

I just pulled the data sheet on the sensor and the peak power consumption is higher than I thought so I edited my original post.
The unit is rated for 3.3-5v power supply and consumes 8mA at standby and 40mA peak. That's a range of 0.3wh-0.2wh in power consumption so it's somewhere in the middle since I don't have data for the real power curve. I would suspect that it's closer to 0.1wh on average during the course of a day, which puts each cell at a similar power consumption to the SOLOE board + solenoid based on Dive Rites ~50hr run time on a 9v battery, so if you're running a pair of cells, SOLOE, and Solenoid off of a 9v, then cut your run time to a third or quarter of what you're getting now. Certainly not all that offensive and if they use rechargeable batteries like the Liberty it's not that difficult to plug it in overnight.

Thank you very much for clarifying. So it could work without any additional power source just with lower runtime. Well, even if one has the runtime at 15-20h this would be more than acceptable in exchange for the solid state cells.
Rechargeable batteries are not recommended for Choppy (at least according to the manual; Ultralife Lithium or something instead). They do work though, but from what I've seen one has to charge them almost daily, on the account of the much lower capacity (think max is about half of what non-rechargeable Lithium provides ie 600mah vs 1200mah; ones I've seen in use though were like 200mah or something hence the almost daily charging)

Out of the curiosity, I wonder if one day we shall see different batteries than 9V used - for example a pair of 21700's or something, that would provide much greater capacity...but then the question is if that makes sense ;]

 

[tbone1004]

Thank you very much for clarifying. So it could work without any additional power source just with lower runtime. Well, even if one has the runtime at 15-20h this would be more than acceptable in exchange for the solid state cells.
Rechargeable batteries are not recommended for Choppy (at least according to the manual; Ultralife Lithium or something instead). They do work though, but from what I've seen one has to charge them almost daily, on the account of the much lower capacity (think max is about half of what non-rechargeable Lithium provides ie 600mah vs 1200mah; ones I've seen in use though were like 200mah or something hence the almost daily charging)

Out of the curiosity, I wonder if one day we shall see different batteries than 9V used - for example a pair of 21700's or something, that would provide much greater capacity...but then the question is if that makes sense ;]

the 9v is a holdover on the solenoid, nothing else. They can use lower voltage solenoids but with USB-C and everything else out I think we will start seeing units with rechargeable batteries built into the heads similar to the Liberty. Going with bigger batteries like the X with 18650's means the heads are big and with the trend for smaller and smaller units I think we will see smaller rechargeable battery packs that are not removable to allow for higher voltage. Either way, the good thing is that the DiveCAN units as they are currently configured can all handle them for at least one scrubber duration on the stock battery configuration.

 

[Wibble]

As a Revo diver, I'm not sure I can afford the upgrade to solid state ;-)

Looks really neat though. If they're as good as people are saying, there's no need for more than three cells, maybe even less if there's a single failure mode.

 

[tbone1004]

As a Revo diver, I'm not sure I can afford the upgrade to solid state ;-)

Looks really neat though. If they're as good as people are saying, there's no need for more than three cells, maybe even less if there's a single failure mode.

these cells will be adequate for 2-cell operation similar to the Poseidon configuration. One cell drives everything and the second cell is a validation cell. If they start to disagree then that's up to the manufacturers to decide if you get to choose which one to run off of or if you bail out. 3 cells recommended if you are doing dives where you really need to stay on the unit if something goes wonky, but for 99% of rebreathers out there, 2 cell operation is more than adequate since these aren't going to be subjected to things like current limiting, linear deviation, etc. that we get with galvanic cells. They're pretty much working or dead, and frankly I much prefer that to something that has a ton of different failure modes that are irritating as hell to diagnose and deal with.

 

[Wibble]

Reckon that the Revo could have two (or three) of those cells with the outputs shared across the controller (Petrel) and monitor (Nerd). Although there's then a shared failure point.

If there's only 2 or 3 Solid State sensor cells used, the spare Revo cell tray space could be taken up by the electronics (maybe, if it fits).

Hopefully those cells are good for the big-time. There can only be a few hundred Poseidon units at most. Once others start using them any weaknesses will come out on show.

Hopefully the manufacturers will make the effort to design upgrades into their systems.