On Tue, Nov 15, 2011 at 09:21:50AM -0800, exp30002 wrote:
>
> Hello;
>
> Nice experiment. ═I would be more interested about what happens
> when a full battery is immersed in seawater. Or when a battery array
> connected and immersed. Or when a larger surface and a large current goes
> under seawater. ═As it could happen on an electric boat.
Good questions all! Off the top of my head, I'd say that much would
depend on the total voltage as well as the distance between the
terminals with that voltage. Obviously, there would be a lot of
conduction paths with a flooded bank, and the total effect would not be
calculable, but the worst-case situation could be approximated based on
the last two factors.
> Or for example inside the boat a battery pack is immersed in seawater,
> and the produced gases fill the inside of the boat. What kind of corrosive
> actions
> can happen.═
On reflection, I actually did learn something from that experiment that
I didn't realize initially. When I was a kid, I hooked up a system that
produced clouds of chlorine - 220VAC (this was in Russia) and a glass
full of heavily-salted water. It's quite impressive, actually. :) This
time, however, the little bit of fizzing produced _no_ perceptible
chlorine - and the salted water (not visible in the video - I kept it
going for a while afterwards) turned a rather nasty gray. In addition,
one of the wire ends was almost completely eaten away after about one
minute.
My conclusion is that the _copper_ plated out - that's what all the
fizzing was - but no chlorine got produced. I'm quite familiar with the
smell as well as the effect (the back-of-the-throat scratchiness) that
even a very small quantity of chlorine produces, and even a tiny amount
of it would be instantly perceptible; none was, even after a minute or
so of running. It would probably take a chemist to determine the exact
breakdown, but not being able to smell any chlorine seems pretty
definitive to me. I can re-try it with larger terminals (more metal to
"burn" before the terminal is gone), but I still doubt that any chlorine
will result.
All this, incidentally, is based on a saturated solution of salt.
Seawater is nowhere near that concentration.
> Two small electrodes into water from one battery is not what is going to happen
> or mishappen on an electric boat.
Since the current is very small, the cross-section of the conductor
shouldn't matter very much. In addition, the contacts on a battery are
much further apart (about 50X) than the terminals I used - I was trying
for a worst-case scenario.
> ═Most likely. I hope my comment is
> constructive. I appreciate the time and effort of the video.
Gabe, I found it very constructive - good food for thought, thanks! I
might even try another experiment and record it. :)
--
Ben Okopnik
-=-=-=-=-=-
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