Q re AI and Pony Bottle pressure gauge attached to first stage.

[tbone1004]

@HeliMech that's what I do....

 

[2airishuman]

I really like the idea of AI, but the drawbacks -- reliability, cost, dealing with multiple reg sets -- are all fairly serious.

Mechanical SPGs are reliable and when they reach their end of life, they ordinarily give plenty of warning before failing completely, either by flooding, by loss of calibration, or by starting to stick. It's pretty rare to have to sit out a dive, or end a dive early, because a mechanical SPG has failed. Like other components of the regulator assembly, I don't carry a spare SPG, but I do carry a complete spare regulator assembly on dives to remote areas.

As I see it, the value in button SPGs is in allowing visual confirmation that a cylinder is full at the beginning of a dive. The accuracy varies widely, in my experience, from one to the next even among the better designs, especially towards the low end of the pressure range. I use one on my pony reg, and it's fine for that.

 

[HeliMech]

@HeliMech that's what I do....

Thanks Tbone. It's coming off my first stage tonight.

Just curious if you roll with a Perdix AI too, for how long and how the AI reliability has been for you.

Ever need that old SPG to get out of a jam?

I've only had my Perdix since Dec. but it seems to be super accurate and rock-solid with the pressure indication so far.

 

[tbone1004]

@HeliMech I have eaten through the first set of batteries on the transmitter. Have probably 30 hours? Never lost signal. I had them on both posts of my doubles and never had an issue on either post. This last trip, I got a low battery alarm and one of them cut out with the other being extremely intermittent. If I put my wrist back almost on top of the transmitter it would catch a signal and then drop it when I got back. The Perdix "stores" the last pressure reading for a bit though which is nice.
I changed the batteries on the SIT and no problems on the next dive.

I don't expect to ever need to put an analog SPG on, just new batteries since there is no battery indicator during normal use. My current thinking is to replace prior to any "big" trip and just eat the battery cost

 

[HeliMech]

@HeliMech I have eaten through the first set of batteries on the transmitter. Have probably 30 hours? Never lost signal. I had them on both posts of my doubles and never had an issue on either post. This last trip, I got a low battery alarm and one of them cut out with the other being extremely intermittent. If I put my wrist back almost on top of the transmitter it would catch a signal and then drop it when I got back. The Perdix "stores" the last pressure reading for a bit though which is nice.
I changed the batteries on the SIT and no problems on the next dive.

I don't expect to ever need to put an analog SPG on, just new batteries since there is no battery indicator during normal use. My current thinking is to replace prior to any "big" trip and just eat the battery cost

Thanks for that. Battery changes like you say are manageable. We think alike there. Sounds like your confidence in the reliability of pressure indication is high.

Guess we didn't pay all that hard-earned cash to Shearwater for nothing.

 

[PalauDiver]

I have a small gauge on my 1st stage, not for anyone else to read but for when I am on the surface and I can verify the pressure on a new tank. It would be absolutely useless during a dive. If my AI goes, I would end the dive. That has never happened though.

 

[Jay]

one other reason to have one would be for when your tank is being changed / setup by dive co's staff (at resort, LOB etc); their visual check that the tank has correct pressure (unless you leave your AI enabled computer on and within range and they know how to view it / ask you to check).

 

[divad]

nevermind