Vance,
Suppose one is inclined to put a 48V (245 ah) bank of AGMs in a pod, ....what can you do failsafe wise if it floods? If you are discharging submerged, vent caps are closed so as not to flood the crew, so what can be done if anything to avoid "depth charging" yourself?
Joe
From: vbra676539@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Real Live Submerge Testing on a 12 Volt Lawnmower Battery
Date: Tue, 07 Aug 2007 16:29:12 -0400
Brent,Will you be using lawnmower batteries for your submarine? I'm thinking not, and I'm also thinking that you need to talk with the manufacturers. Your experiment had somewhere in the neighborhood of exactly zip to do with a seawater intrusion incident, which has more to do with voltage levels and maximum load potential than anything else. Offshore, we often used a plastic barrel of seawater to deep discharge banks when equalization was necessary; just take two cables, positive and negative, add a couple of feet of copper to the ends, and dip. You'll get boiling water in no time, my friend, trust me.
As for chlorine gas, let me give you a cautionary tale--two, actually, one of which I was involved with. Two battery explosions, one on PC-9 and one on the old PLC-4. The former made VISIBLE chlorine gas (it really is green, by the way), and the latter blew a two hundred pound hatch completely off the submarine, all the way across the shop, and THROUGH a tin wall. Those were both 120 volt systems, with a 220 amp capacity. PC-9 got flooded with seawater due to a pod leak, which caused the violent discharge, which caused the acid to boil, which separated water into hydrogen and oxygen, which ignited and caused a horrific bang, pretty much in that order. Deep Diver had its charging vent closed during charging (an oversight), bubbled out gas, and when the overload came (from the over-charging), popped an internal in-line fuse, which made a spark, which made another one of those horrific bangs, and might well have killed a few people, had they not all been outside for lunch,! possibly congratulating each other on how clever they were.
Testing is one thing, my friend, but Ben Franklin at least had enough sense not to fly a kite on metal wire. Otherwise, we might never have heard about it. I'd hate for the same thing to happen to you. And, if I had to guess, I'd say your lawnmower battery probably has some warped plates, which means it ain't going to last much longer, all things considered. No harm, no foul? Maybe, but PLEASE, don't let this get to be a habit. There's as awful lot of potential in a battery bank, and it'll bite your butt if you aren't careful.
Best Regards,
Vance
-----Original Message-----
From: Brent Hartwig <brenthartwig@hotmail.com>
To: personal_submersibles@psubs.org
Sent: Tue, 7 Aug 2007 2:54 pm
Subject: RE: [PSUBS-MAILIST] Real Live Submerge Testing on a 12 Volt Lawnmower Battery
Ron,
When the battery was in seawater, the water slowly turned yellow. I'm not sure why. I don't have a way to test for Chlorine gas at the moment. Is there a cheap test, can you smell it? I'm not sure I want to smell it. When I make colloidal silver by electrolysis of pure silver electrodes, the distilled water becomes a light yellow. Perhaps the lead post are sluffing off lead into the water.
Regards,Brent Hartwig
=
Date: Tue, 7 Aug 2007 10:23:07 -0700
From: ronleonard@shaw.ca
Subject: RE: [PSUBS-MAILIST] Real Live Submerge Testing on a 12 Volt Lawnmower Battery
To: personal_submersibles@psubs.org
Anyone heard that a battery submerged in salt water produces Chlorine gas? From those in the battery industry that I have asked it would appear to be true.If it is correct, that would be a much larger problem than getting shocked or splashed with acid.RonFrom: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent HartwigSent: Monday, August 06, 2007 10:28 PM
To: PSUBSorg
Subject: [PSUBS-MAILIST] Real Live Submerge Testing on a 12 Volt Lawnmower BatteryWell Boys and Girls, I did some testing.
Ya I know that usually means vacate the area with or without your shorts, to another county. But it's to late, I already did it. One can talk about it for only so long before they get off there arss and get dirty. It's more fun to.
So I removed a fully charged 12 volt lawn mower battery, I could do with out until next week, if it blow up anyways, and I did some testing. I then obtained a five gallon bucket, jumper cables, lots of protective clothing, and a full face shield, among other things. I then put the battery in an empty bucket and then put the end of the hose into it. Then I remotely filled the bucket with slightly hard freshwater, I don't remember what the PH of my water is. Nothing happened, or at least that's what I thought at first. I then removed the water and battery from the bucket and attached jumper cables to it in the normal fashion. When striking the ends of the cables together I got the normal sparks. When I put them underwater there was some weak hydrogen production from the negative lead. Then when I touched the leads together underwater, I got the same basic spark as I did out of the water.
Then I went and found my old stash of aquarium stuff, and pulled out some Instant Ocean brand sea salt and mixed it in freshwater, until I got a specific gravity of 1.21, like most sea water. I then removed the freshwater from the bucket and added the saltwater for some more testing. I tested the leads in the same way and got the same result, but with a bit more hydrogen production from the negative lead.
Next I added enough salt into the one gallon in the bucket to make three gallons of sea water, so I could completely submerge the battery. But before I added the water I mixed in the salt and tested the leads again. Now when I put the leads into the water on either side of the inside of the bucket, the negative lead produced allot more hydrogen. When I then touched the two leads under water there was a larger spark on the tangent surfaces and they tried to stick together. They didn't try to stick together in freshwater and not much in normal sea water. Point is that if you take your sub to the Great Salt Lake in Utah be careful.
Now I added two more gallons of freshwater to the mix, to get a specific gravity of 1.21 again, and put in the battery remotely. Nothing much happened, just some hydrogen production from the negative pole. This was just a cheap normal battery, not a AGM sealed type. I then did some testing and then put my bare finger in the water. Nothing, not even a tingle. I then lowered the level of the water to about an inch over the top of the poles. Then did some more testing and then put my finger directly between the poles, nothing.
I then removed the salt water and refilled it with freshwater and did the same testing, nothing. I would say that the battery would of slowly discharged by producing hydrogen until spent. No explosion when submerged in this way. The hydrogen in an enclosed space would be real bad news. You'll be safer in freshwater then salt since you'll have more time to get out before the hydrogen levels get to high. Still you better get out ASAP unless you can route the hydrogen into your AIP unit quickly. ; )'
Finally I reinstalled the battery in the mower and started the mower with no trouble. I learned allot from doing this, how about you? Just remember I'm a submarine half full kind of guy.
Here are my pictures of the submerged battery testing.
http://www.frappr.com/?a=viewphoto&id=4001713&pid=7357670
Regards,Brent Hartwig
"Do or do not, There is no try"
~ Yoda
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