Dive Computer Failure- What Happened?

[BillP]

Background: I have 3 old dive computers that I still use, but are no longer supported by the manufacturer (ie- they no longer supply battery kits). My LDS changed the batteries right before a recent trip, but did not change the o-rings for the battery compartments because they could not get them directly from the maker, and apparently didn't feel comfortable using off-the-shelf o-rings. The old o-rings “looked” fine. They pressure tested the computers after the change (to a little over 60') and they passed.

Failure: The first computer failed on my 3rd dive, about 2 weeks after the battery change. On that dive it almost immediately said that I had 26 minutes of deco time, and then it went dark. (No big deal, I had a backup with the same algorithm in my pocket that did not fail on the trip.) The second computer that my buddy was using failed after the last dive of the trip. The battery warning came on at the end of that dive at the safety stop and it soon went dark also.

Findings after the failure: When I opened each battery compartment (½ AA, 3.6v, lithium batteries) shortly after returning to shore the positive contact in each computer was completely GONE. In their place was a pile of brownish crud concentrated around the positive end of the battery much like the whitish crud you see around the ends of an alkaline battery that you let discharge completely. The brown crud was pasty like it was maybe mixed with a little water. The negative contacts were pristine. There was no visible water in either compartment.

Analysis: I assumed that each compartment had a minor leak at some point and the positive contacts dissolved by electrolysis. I believe the computers failed once the contacts had dissolved enough that the batteries were no longer supplying power? A repair tech at a second level support center for the manufacturer that I spoke to had not seen contacts vanish like that before.

I would be interested in others' experiences with computer failures and other opinions about what happened and/or where the positive contacts went.

I'll start another thread later with specifics about my computer saga where you can debate manufacturers orphaning older gear, the wisdom of relying on old computers, re-using o-rings, etc.

 

[DIVEWATCHDOCTOR]

BillP, sorry to hear that. You can certainly trace what happened to re-using the "old" Orings. Every dive computer manufacturer that I know states (particularly for the "user replaceable battery" models): "use a new Oring when replacing the battery". People in this forum even brag about having reused the same Oring not once, but several times. O rings get compressed and slightly warped after seating one or two years in your computer. It takes just a little irregularity to cause a leak and I guess that's what happened in your case. Although it might be too late now, provide us with the brand and model of your computers and most likely we'll be able to tell you which is the correct Oring size.

 

[BillP]

Thanks DIVEWATCHDOCTOR. I agree that reusing the o rings was the cause of the failures. I imagine that they not only become compressed and warped over time, but also could change in hardness if old enough. I actually already have replacement o rings now. Lesson learned.

I'll be posting that other thread that I mentioned with specifics about my computer failure and what I did to get them up and running again. I look forward to your thoughts on the process.

Until then, any thoughts when the computers most likely flooded (e.g. immediately before failure, or did it take awhile for them to fail) or on where the positive contacts went when they disappeared?

 

[DIVEWATCHDOCTOR]

I am not a chemical engineer but to me, the positive contacts in your computers were victims of corrosion and totally disintegrated. I'm guessing here but some tap water might have gotten into the battery compartments when the computers were pressure tested. But the really destructive corrosion started when you took the computers to dive and a little sea water also got inside. Salt water corrodes much faster than tap water.

Through the years I have inspected several flooded dive computers (of the type on which the battery is in a separate compartment from the electronics): for instance, Suunto Geeko and Vyper, Oceanic Datamax and Data Plus, Scubapro Aladin Prime. In a couple of those occasions, they had been flooded for several days and the positive contact had also vanished. If the flooded computer is of the type in which the battery is not isolated from the electronics (like the most expensive ones such as the Suunto D series, or the Oceanic OC1 and OCi), death occurs almost instantaneously after any kind of water creeps in. Usually, the display is the first to fail, followed by the electronic circuit.

 

[KeithG]

BillP, sorry to hear that. You can certainly trace what happened to re-using the "old" Orings. Every dive computer manufacturer that I know states (particularly for the "user replaceable battery" models): "use a new Oring when replacing the battery". People in this forum even brag about having reused the same Oring not once, but several times. O rings get compressed and slightly warped after seating one or two years in your computer. It takes just a little irregularity to cause a leak and I guess that's what happened in your case. Although it might be too late now, provide us with the brand and model of your computers and most likely we'll be able to tell you which is the correct Oring size.

Let's not get too excited about replacing orings "every year".

They should be replaced as required. Hard, square, falling apart, gooey? Then replace as required. Did your oring have any issues that required replacement?

If not, then unfortunately most likely the issue was incorrect oring lube, installation and/ or door closure. User error.

Same result would have happened with a newer oring.

 

[BillP]

Hi DIVEWATCHDOCTOR. The battery compartments were isolated and the electronics compartments did not flood. I looked through the compartments' "windows" after the battery changes and did not see any water from the pressure tests, but I suppose that there could have been a small amount. On the trip I did not take the computers out of their boots to inspect them until they failed.

Thanks giffenk. In my case the o rings were several (5+) years old. Again, they looked and felt OK, even when I took them out after the failures. No sign of pinching or crushing and they seemed to be in the right place. I was able to find out the size of the o rings and get some for the future. I believe that I should have waited until I had replacement o rings and asked my dive shop to use them if they didn't feel comfortable using their own, but I wanted the computers ready in time for the trip.

I could certainly see user error as a likely cause of failure if I had replaced the (supposedly not user replaceable) batteries myself which is why I took them to my LDS for the change. I had computer failure in 2 out of the 3 computers for which they changed the batteries. I would hope that their equipment person knows how to place an o ring, but it could have been an error.

 

[KeithG]

Likely user error by the LDS. A pressure test to 60 feet is nonsense.

 

[JamesBon92007]

BillP, sorry to hear that. You can certainly trace what happened to re-using the "old" Orings. Every dive computer manufacturer that I know states (particularly for the "user replaceable battery" models): "use a new Oring when replacing the battery". People in this forum even brag about having reused the same Oring not once, but several times. O rings get compressed and slightly warped after seating one or two years in your computer. It takes just a little irregularity to cause a leak and I guess that's what happened in your case. Although it might be too late now, provide us with the brand and model of your computers and most likely we'll be able to tell you which is the correct Oring size.

I've also read that AquaLung says it has to be their O-ring or it voids the warranty.

This may be a little to the side of the topic, but I've also been reading about depth sensor failures. I'm wondering if anyone has a solution to help prevent this failure. I intend to thoroughly rinse my depth sensors after each dive with the idea that it might be salt crystals that are the culprit.

 

[BillP]

Likely user error by the LDS. A pressure test to 60 feet is nonsense.

Yeah, I'd have to say that there was a user error by the LDS. Whether they installed the o rings wrong, erred in not replacing the o rings with new ones, or should have done like other dive shops and refused to touch the computers if they were uncomfortable.

The Level 2 service center that fixed the computers took them down to 100' for a pressure test after the repairs according to the computers' logs. What do you do with your battery changes?

I've also read that AquaLung says it has to be their O-ring or it voids the warranty.

Good point. I wouldn't be surprised if that was a requirement of every computer warranty. Unfortunately, my very old (but perfectly functional) computers were about 20 years out of warranty.

 

[Scubagaskets]

Hi there All. since you are talking about dice computer o-rings just informing you that at scubagaskets we run a 25% discount on all of our dive computer o-rings

Diving Computers O-rings -Scubagaskets scuba o-ring provider