Dear trymixdiver,
I own a Beuchat Aladin Pro, purchased in the early eighties when they first came out on market. I have replaced the battery twice. The first time I used jumpers to maintain voltage to the computer while soldering in the new battery. I did this before the battery went dead.
Recently I replaced it a second time after it sat on a shelf for 5 years. The Batt Low indicator was diplayed. When I tried to turn it on by placing my wetted finger across the contacts it went dead altogether.
With nothing left to lose, so to speak, I replaced the battery without the extra care of jumpers. Battery cost $10.45. While this is an usual battery, originally used for mil applications, it isn't hard to find.
The unit at first seemed dead....then I used some scotchbrite, buffing the contacts, and it came back to normal operation. I just used it for a week of diving on Roatan, comparing it's reading to others diving similar profiles. My 20 year old, beat up and ugly after being drug thru wrecks etc. etc. computer is still working fine.
If you are going to attempt to do this yourself there are only a few things to be aware of. The battery as originally installed bythe manufacturer probably has tabs on it for soldering to. My first replacement did but the second did not. This complicates the soldering (all soldering should be completed quickly so the heat buildup doesn't damage the battery, and generally you should not deprive a computer of voltage for long so that it desn't dump any violatile memory...good design should dictate nonviolatile for any program memory but I don't want to assume that) So I believe you should use a good clean soldering iron of medium heat that is suitable for electronics repair. Also use soldering paste that will clean the battery contacts of any oxidization so the leads fom the computer will get a good quick contact to the battery. Your enemy here is too much heat applied to the battery for too long.
This sounds difficult and complicated but believe me it isn't. If you've not done any electronics repair, find a friend that may have been trained in the military (milspec, or any good soldering trainng in school and it will be a piece of cake.
If you have any further questions feel free to contact me.
multistrada
northern illinois