Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
Ability to post and comment on topics and discussions.
A Free photo gallery to share your dive photos with the world.
I have three Oceanic branded PPS transmitters. All were bought secondhand so I don't know exactly how old they are (bought 14, 16 and 18). All are going fine and interestingly I get way more than 300 dives from a battery (and I do long dives).
I had emailed Shearwater about the issues I experienced, as I had a theory involving helium and MEMS oscillators. That does not appear to have anything to do with the problems I had. But, they did email me back with some good info. For all of your information. This is from Shearwater - not PPS. This is also why, in the future, I will stop buying transmitters that are branded/sold by the other vendors and insist on only buying the Shearwater-branded ones. Because of the customer service they give. Also, it seems that the other manufacturers only give a 1-year, non-transferable warranty (I think) on the transmitters, and Shearwater gives the same 2-year, transferable warranty on the transmitters that they give on their computers.
There was a design flaw in earlier transmitters that we identified and alerted Palagic to. The design flaw was very rarely experienced by customers. I'm surprised that you have seen two fail in this way. That is an unfortunate coincidence.
The flaw does not pose a safety risk as it only occurs on the installation of a new battery. Essentially, when a new battery is installed there is a small chance the processor will lock-up and draw excessive power from the battery. The processor is not operating when this happens. This excessive power draw causes the battery to get quite hot like you experienced.
We developed a fix and passed it on to Pelagic who incorporated the change into all of the new transmitters.
From our testing, if the hot battery is removed there is a really good chance that putting in a fresh battery will cause the transmitter to operate normally again, but we are replacing transmitters for everyone who experiences this issue.
So, if you have an older PPS transmitter, when you eventually have to replace the battery, that is when you should be on the lookout for this problem. Put the new battery in and the cap on and pressurize it (i.e. put it on a reg and put that on a tank and turn the tank on). Keep your hand on the transmitter. If it starts to get warm (mine took about a minute to notice it getting warm), turn off the tank, depressurize the line, and take the battery back out.
If you could feel the transmitter getting warm, the battery itself will likely be HOT. Toss it, put in a new battery, and try again.
Through it all, also have your computer on and make sure that you are also getting a pressure reading (or not). I got no pressure reading on my computer when the transmitter was having this issue. So, if you get a pressure reading, you're probably good to go. But, I would still monitor it for a minute or two to make sure the transmitter doesn't start to feel warm.