Current State Of Rebreather Electronics

[AdamSa]

I have decided that it is time to switch to CC diving and i am currently looking into what unit to get. I am mostly inclined towards the JJ because it gets solid reviews and all my rebreather buddies dive JJs. My first instinct was to buy the unit new to avoid any unnecessary issues when starting out.

What is holding me back at the moment is that the electronics on the unit are rather old. If I am not mistaken the electronics have not really been updated since 2014 (Petrel). This seems to be true for most major re-breathers.

So i guess my question is, what is your opinion on the current state of electronics on Rebreathers? Would you at this time think it smart to buy a new unit which could well be outdated soon?

 

[Griffo]

Here's my understanding from too much time reading and no practical experience.
SW basically set a new standard for reliability with their DiveCAN network based approach for DC to CCR interfacing. The use of this standardised protocol means that when a new DC or module becomes available, it should be fairly easy to swap out the unit or add in a new module.
The Petrel 2 is currently their only computer with the Fischer connector, so while it might be 4 years old, it still has the latest firmware and is effectively still considered the leading solution.

 

[rjack321]

The newer JJs are outfitted with divecan.

I would buy a used unit however, you might hate it or want something else once you have the hours on it to know. Sell the used unit for close to what you paid and you are no worse off.

 

[Superlyte27]

The only unit with a better computer (which is relative) is the Liberty. Full disclosure, I'm a liberty instructor, but have dove both ccr's and decided the liberty was a better unit. It breathes better, dives better, and converts to sidemount. I like the JJ alot. All of the other CCRs I'm cert'd on and own use the Petrel. There's no issue with them at all. If it's not broke, don't fix it. Which is why you don't see an upgrade for the last five years.

 

[tbone1004]

what @Griffo said is correct. Since the new units use DiveCAN which is essentially a standard canbus architecture, there isn't a whole lot to "upgrade". We haven't had any changes in cells in 20+ years so the oxygen monitoring side isn't going to change. The solenoids are standard industrial solenoids and those haven't changed in eleventythousand years either. The base components are now digital so unless there is a major change in technology, they don't need to be upgraded since there is no real processing power required in the units. Even on the "most advanced" units like the Liberty, XCCR, APD, etc. that have more than just O2 going on, they have negligible amount of processing to do.
If we look at Shearwater computers, the real differences between a Predator and a Perdix are pretty negligible. The Petrel came about because of a new screen, whoopdedoo, but the Predator was first used as a controller with the DiveCAN units and the processing capability between the two is pretty much the same. The Perdix is "newer" but it doesn't actually "do" anything more than the others with the exception of AI. AI is just a module on the main board, not a full redesign of the non-ai version.
All that to say that the DiveCAN architecture is there to allow future upgrades and additional modules without having to redo the entire thing which is the beauty of digital controls. Even though the JJ hasn't been redone since 2014, it's because there is nothing since then to do. Unfortunately they haven't added AI to the Petrel yet, but even that would just be a controller upgrade. Poseidon hasn't fully released the optical O2 sensor yet. He sensors are not stable in the Liberty inside of the breather with many of the going sideways with moisture, same with CO in other units. The DiveCAN is capable of handling all of those things and more, just up to the manufacturers to install them.
Personally I think it's going to be a very long time before you see any rebreathers with a major controls upgrade because the CANbus system is just that good. APD and Divesoft have their own versions of it, Shearwater pretty much controls everything else, and while you'll see modules added and upgraded, I don't think the base system will get any major changes

 

[uwxplorer]

He sensors are not stable in the Liberty inside of the breather with many of the going sideways with moisture, same with CO in other units. The DiveCAN is capable of handling all of those things and more, just up to the manufacturers to install them.

Interesting statement. I noticed a recent firmware update allowing to disable He reading. I am wondering whether this is intended to address this (without mentioning the root cause, as it were)?

 

[Superlyte27]

Not sure. I haven't had any issues with mine yet.

 

[broncobowsher]

If all your buddies dive a JJ, that is a very good reason to dive a JJ.
The only thing about a 5-year old machine is that the physical parts are 5 years old. Rubber ages regardless of use. That is easy to fix with servicing those parts.
About the only change I have noticed over the years (and I don't know if it applies to the JJ) is to get away from the Fischer connectors and move toward the wetmate connectors. Looks like most new stuff from Shearwater is running the wetmate unless it has to be a legacy product and needs to be a Fischer.

 

[tbone1004]

Not sure. I haven't had any issues with mine yet.

if you start diving it a lot in sidemount you'll find issues with it. Most of the time you can blow it out after diving to dry out, but it's been a common problem with them in sidemount.

 

[Aquanomad]

I think the NERD2 was a good step forward. Subtle firmware upgrades and a tidy controller. Some people dont like them but it puts the info right where you need it. For those of us multi tasking with busy hands it was a welcome addition to current choices.