BillP
Senior Member
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.
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.