Air integrated computers…backup?

[doctormike]

Right. And that was largely my point. Diving with a single SPG is fine in just about everyone’s eyes. I never see anyone calling for diving with two on a single 1st stage. Yet, I hear plenty of people insisting that diving with a transmitter requires a backup SPG.

Yeah, this is an excellent point. I don't like AI, I just use a single SPG for OC diving. But I have never seen anyone recommend or use two SPGs on a single gas source. And from what I can tell, modern AI has a lower failure rate than a brass and glass SPG (which I have seen fail).

 

[Belzelbub]

Shearwater talks about the fuel gauge for the Petral in this video and I’d assume the same is true for transmitters:

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.

 

[scubadada]

@scubadada, thanks for the report. What are you using for logs? You might make a feature request.

As a data point for others, Subsurface-desktop shows the transmitter battery status from a Teric download. I believe it's reported as one of three values (normal, low, critical) rather than a voltage.

Shearwater Cloud Desktop 2.8.3 for the Teric, OceanLog 2.5.2 for the VT3

I have nearly 12 years, 1724 dives from the VT3, less than 3 years, 383 dives from the Teric. I have just been too lazy to try Subsurface, knowing that I could download both. I may still do that.

 

[Belzelbub]

modern AI has a lower failure rate than a brass and glass SPG (which I have seen fail).

I’m pretty sure I have as well, recently. I was diving at the aquarium where I volunteer. Shallow dive. I checked my SPG (Aquarium’s gear) and it read 3000. I checked my computer and it showed 15 minutes dive time. Given that I started with 3100, this did not compute. I know I can easily dive for well over an hour in this habitat, I also have a spare air, and could do a CESA from this depth without any drama. So I flicked it a few times and continued. I checked gain at 40 minutes and saw just under 2000 psi. This made more sense, so I guess my fix worked.

I can’t say that I’ve seen a transmitter fail, but have seen a failed transmitter. NO COMMS was displayed. Changing the battery resulted in the same message, so it was sent out for service. Apart from a low battery, this is what I would expect from an electronics failure. They usually fail on startup.

 

[Belzelbub]

I have just been too lazy to try Subsurface, knowing that I could download both. I may still do that.

I’d recommend giving it a shot if only for scientific curiosity.

If the Transmitter status on the previous dive shows normal, then it may have just been a bum battery. If it shows low or critical (or anything other than normal) and the Teric didn’t display the warning, then you may have another Teric case to add to your collection.

 

[ScubaBadger32]

Used to have an AI dive computer in console but that proved to be unreliable (Suunto Cobra, enough said), now I use two hoseless AI dive computers from two different mfg, Ratio and SP.

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!

 

[scubadada]

What kind of batteries do you use as some like the Energizer Ultimate Lithiums have a very flat discharge curve that means they can die pretty quickly wilh little or no advanced warning:

https://data.energizer.com/pdfs/l91.pdf

Shearwater talks about the fuel gauge for the Petral in this video and I’d assume the same is true for transmitters:

I use Duracell CR2 Lithium batteries in my transmitter.

I usually change the transmitter battery when I change the battery in my VT3, around 200-250 dives. I neglected to do so last time, as I changed the computer battery in the middle of a trip. This transmitter battery was nearly 3 years old, just short of 400 dives and over 400 hours. I'm still disappointed I never got a transmitter battery warning from my Teric.

 

[scubadada]

...If it shows low or critical (or anything other than normal) and the Teric didn’t display the warning, then you may have another Teric case to add to your collection.

I hope not!

I may give Subsurface a try, thanks

 

[Belzelbub]

I use Duracell CR2 Lithium batteries in my transmitter.

I usually change the transmitter battery when I change the battery in my VT3, around 200-250 dives. I neglected to do so last time, as I changed the computer battery in the middle of a trip. This transmitter battery was nearly 3 years old, just short of 400 dives and over 400 hours. I'm still disappointed I never got a transmitter battery warning from my Teric.

Duracell is a red flag for me. I’ll use just about anything but.

3 years and 400 hours, though is respectable. I still would have expected a warning though. I think I’ll stick with my annual battery changes for the time being even though I know it’s overkill.

 

[DAJ]

I just don’t get the need to dive with both a transmitter and an SPG.

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. I ordered a HP swivel for the Y valve setup so I can run the transmitter between the 1st stages instead of having it hang off the side like it does in the pic.