Do electronics like saltwater?
by Thorsten von Eicken
Ocean Sports Fitness Tracker
Picture yourself swimming in the ocean and looking at your electronics bathing in the saltwater next to you…
Well, that’s what happened to me a couple of weeks ago! Surfing down a wave I tipped to the side falling out of the surfski. I somehow managed to flip open the latch of the tracker’s case with my toes. So there I was, swimming next to the surfski and seeing the box open and the PCB plus the battery plus the little foam dividers all happily bathing in the ocean water! Before the next wave washed everything away I somehow managed to stuff everything back into the box without too much water and lock it back up. What’s your guess, anything salvagable here?
Li-Ion cell with gunked top after saltwater bath
Back home I inspected the damage. The top of the battery had a whole lot of dark goo. It must be toast. But still registered 3.1V! Interesting… Lots of white crud all over the PCBs. I spent some time cleaning them with denatured alcohol and then plugged everything into a current-limited power supply and started to apply power. To my great suprise the display came on and showed the normal info!?
What didn’t seem to just work was the bluetooth heart rate info. After a good hour of troubleshooting I concluded that the bluetooth radio’s output stage must have gotten fried in the bath. Probably the radio was transmitting and the output got short-circuited. The module seemed to work perfectly and respond to commands as expected, but it simply wasn’t seeing any of the bluetooth devices around my desk. I ended up ordering a new one and when I put it in it worked right off the bat.
Looks like I got really lucky that not more broke and that everything was held in place by the cables long enough for me to collect it before it would sink! For my next prototype I will make sure that the latch can’t be accidentally opened with the toes!!!
To be continued…