I agree, dunking a battery in salt water is a non issue. Perhaps if you completely submerge an FLA, a little salt water might get into the acid and ruin your battery chemistry but a deadly cloud of acid vapors seems unlikely.
However, if your batteries are configured for something considerable more than 12V, say 10 of them in series to give you 120V, or more, all kinds of mischief may ensue from current actually flowing thru the salt water or making continuity to something metal that it could then flow thru and short out the system with potentially catastrophic consequences. And they don't need to be submerged, just some salt mist buildup can do this. Not to mention, everything that had a salt water path from the battery terminals to anything metallic would be likely to shock you. I have seen 120V systems on land short out from salt spray and have personally been shocked by ungrounded equipment that had salt spray on it.
So perhaps this is why the Coast Guard requires you to have those fused disconnects every 48V in high voltage battery banks. Maybe those burdensome government regulations that require us to add all that extra stuff are actually there to protect us from our own ignorance.
ANY posibility for this to happen in a high voltage system is a another good argument against running high voltage systems on boats that travel in salt water. So if you're going to run high voltage, you need to keep your batteries dry and salt free, something that is going to be challenging to always do.
From: Ben Okopnik <ben@linuxgazette.net>
To: electricboats@yahoogroups.com
Sent: Wednesday, November 16, 2011 7:49 AM
Subject: Re: [Electric Boats] Re: Where to even start
On Wed, Nov 16, 2011 at 06:19:40PM +1100, Matthew Geier wrote:
> >
> I'd be more worried about what you get when the sulphuric acid
> electrolyte mixes with salt water.
Item #1: Why would the two of them ever mix? The cells are essentially
sealed, even in FLAs. AGMs, of course, would just ignore all that
nonsense happening outside. :)
Item #2: HCl is normally produced by mixing sulfuric acid and salt.
Mixing the acid with seawater, which has an average salinity of 3.5%
(which includes all the salts, not just NaCL) will amost certainly do
nothing: the amount of water you'd need to collect even a small amount
of salt will instantly turn the acid into a very weak solution, before
any reaction can occur.
For what it's worth, several friends have mentioned accidentally
drowning their batteries (along with their fishing boats, etc.) Pretty
much all of them just rinsed them off and kept on using them. Anytime
I've heard of a sunken boat - and that's lots of times, over my 20+
years on the water - all anyone ever worries about is the engine. The
rest of the boat just gets a freshwater rinse and that's it.
--
Ben Okopnik
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To: electricboats@yahoogroups.com
Sent: Wednesday, November 16, 2011 7:49 AM
Subject: Re: [Electric Boats] Re: Where to even start
On Wed, Nov 16, 2011 at 06:19:40PM +1100, Matthew Geier wrote:
> >
> I'd be more worried about what you get when the sulphuric acid
> electrolyte mixes with salt water.
Item #1: Why would the two of them ever mix? The cells are essentially
sealed, even in FLAs. AGMs, of course, would just ignore all that
nonsense happening outside. :)
Item #2: HCl is normally produced by mixing sulfuric acid and salt.
Mixing the acid with seawater, which has an average salinity of 3.5%
(which includes all the salts, not just NaCL) will amost certainly do
nothing: the amount of water you'd need to collect even a small amount
of salt will instantly turn the acid into a very weak solution, before
any reaction can occur.
For what it's worth, several friends have mentioned accidentally
drowning their batteries (along with their fishing boats, etc.) Pretty
much all of them just rinsed them off and kept on using them. Anytime
I've heard of a sunken boat - and that's lots of times, over my 20+
years on the water - all anyone ever worries about is the engine. The
rest of the boat just gets a freshwater rinse and that's it.
--
Ben Okopnik
-=-=-=-=-=-
------------------------------------
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/electricboats/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/electricboats/join
(Yahoo! ID required)
<*> To change settings via email:
electricboats-digest@yahoogroups.com
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<*> To unsubscribe from this group, send an email to:
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<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
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