Air integrated computers…backup?

[Joneill]

Even Shearwater recommends that you should use a backup SPG in the owner’s manual if you use a transmitter. It’s up for you to decide if a redundant system is worth it or not. If you don’t see the need, no point in trying to convince you otherwise. I prefer to have options if something fails, even if that chance is somewhat remote. This is how I run my single 130s now using MK21s in place of MK25s but using a Y valve is a bit different from most single cylinder users. Right post is primary and transmitter. Left post is secondary regulator, SPG, and inflator hose. If I only had one first stage, I would still use a transmitter and a SPG.


View attachment 718133

I suspect that is a legal CYA statement - but, personally, I do like redundancy.

 

[BoltSnap]

which SP? im gonna get a SP (i like their style, yes ive done research, i just like their AI stuff, please dont lecture me on why anyone dives a shearwater) and wanted some input from you!

I recently got the A2. I don't like it because the batteries aren't user replaceable and because the Air time remaining is not on the primary screen, you have to press a button to see your air time remaining.

I don't recommend it. Perhaps the G2 is a better dive computer.

(I am the last person on SB that would tell you to go for SW).

 

[NW Dive Dawg]

I'm feeling like this is going to start WW3 but what the hell...

I dive primarily solo, OC, with a single 120HP and a 19CF tank mounted pony. I have an Oceanic Pro Plus 3 air integrated console on my primary system. I don't do cave or planned deco anymore. I love this console because it's intuitive, user friendly and has big numbers for my old eyes. Also, user changeable batteries. I also have a hose mounted old Sherwood Matrix puck as a backup for just depth and nitrogen loading info. My 19ft tank mounted pony is fully on and fully charged. I do have a small 2 in SPG tied to my pony 2nd stage hose so I can verify pony pressure anytime I want. (see pic)

So....... bottom line is that my fully redundant 19ft pony is my emergency backup in case of a primary air integrated console failure...... and being primarily solo, I'm good with that.


Cheers...

 

[Joneill]

It’s not the same. Unlike the Perdix or Petrel, you don’t have a lot of choices in battery. The transmitter uses a CR2, and it doesn’t transmit actual voltage. Just the three levels.

Where did you find info on the transmitters not transmitting voltage and just transmitting 3 levels? Regardless, the CR2 seem to have pretty flat diacharge curves which means they can “fail” with little advanced warning?

https://data.energizer.com/pdfs/1cr2.pdf

https://www.duracell.com/wp-content/uploads/2021/06/DLCR2_IN.pdf

 

[scubadada]

Where did you find info on the transmitters not transmitting voltage and just transmitting 3 levels? Regardless, the CR2 seem to have pretty flat diacharge curves which means they can “fail” with little advanced warning?

https://data.energizer.com/pdfs/1cr2.pdf

https://www.duracell.com/wp-content/uploads/2021/06/DLCR2_IN.pdf

Do you think the Duracell CR2 would fail in the transmitter without ever registering a low or critically low battery level?

 

[Joneill]

Do you think the Duracell CR2 would fail in the transmitter without ever registering a low or critically low battery level?

I would expect it should signal if it was connected and working before/during the battery failing? I usually swap in new batteries before a trip to be safe.

I actually have gotten low transmitter warnings a few times when batteries were new - but they did not persist and transmitters kept broadcasting - so I kept an eye out but did not replace the batteries (I have a backup transmitter so not a real risk). However, I have not ever had one run out of juice on a dive so not sure if there is a little bugginess with the low battery warning function?

 

[Belzelbub]

Where did you find info on the transmitters not transmitting voltage and just transmitting 3 levels?

From here: Reading Wireless Air Transmitter using Arduino

A small group decided to crack the code for the PPS/Swift transmitters. They even put together a simulator and confirmed that the computers can read the signals. They start to break down the signal data around page 9, but battery info was to come later.

Successful read by Teric in post 106. Transmitter battery information first decoded in post 127. There were 3 values Good, Low, Critical.

 

[scubadada]

...There were 3 values Good, Low, Critical.

These would correspond to no warning, low battery yellow-replace soon, and low battery red-replace immediately

 

[Belzelbub]

Do you think the Duracell CR2 would fail in the transmitter without ever registering a low or critically low battery level?

The Duracell datasheet did look to be a bit flatter than the energizer, but both show enough curve that the computer should register. The SAFT LS14500, for example are much flatter.
https://www.saftbatteries.com/download_file/6X7JMGAnv3Fm6HdmtEv%2B2gtlbZ1bRRVHkjS11M6md92GD2EF7vU%2F3Oybbz3WOlG%2BxR8srpA5iCdJ%2FV3IQzTVHQyiTucngZKEg9KkYCLkowAvgaG1huqyXUIQvO1qUkZjGCfaa8Bj8zATp1fXJiJXWOMWYOmKIKGl%2B2HKVzqrqCHgXSgMPQ%3D%3D/LS14500.pdf

Aqualung manuals make reference to the transmitter levels at 2.7V for Low and 2.5V for. The energizer seems to hit that 2.7V earlier than the Duracell, so might allow for earlier warning.

Aqualung refers to the levels as Warning (Yellow/Low) and Alarm (Red/Critical).

 

[Hoag]

So, I take it you use two SPGs on a single first stage by that logic.

No. Like I wrote, I have a Perdix AI & a Teric both sync'd to the same (Swift) transmitter, and an analog SPG.