Author Topic: Salt Water Cells  (Read 6060 times)

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americanreman

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Salt Water Cells
« on: February 08, 2007, 10:43:33 PM »
Reading another post about making salt water cells (battery) I decided to try it myself since I have everything on hand to do it.


I used 1/2 copper pipe and 1/2 galvanized pipe and put them down through pvc pipe, water was about a tablespoon of salt for every 8 oz.


Length of pipe, volts, amps



  1. " = .5 volts - 5 ma
  2. " = .8 volts - 10 ma
  3. " = .8 volts - 15 ma
  4. feet = .8 volts - 30 ma


I'm a boater and eventually I'm sure to end up in Florida possibly living on my boat so this was of interest to me, running pathway lights and general low voltage, wattage lights for almost free from the water I'm floating in sounds good, but output is dismal.


Maybe if you slit the pipe on one side and opened it up there would be more surface area, it seems that the interior of the pipe is doing little for you but taking up valuable space and water (4 footer was pretty heavy).


I think if you wanted to invest money in the metals and pack as much as you could into a space there might be some logic to it and usable energy.


The other poster said something to the effect that long pieces of pipe could make very powerful batteries, I don't think so...but there are probably good uses for something like this.

« Last Edit: February 08, 2007, 10:43:33 PM by (unknown) »

americanreman

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Re: Salt Water Cells
« Reply #1 on: February 08, 2007, 03:50:47 PM »
Forgot to mention, as you can see the 2 inch sections could be more efficient and powerful than long pieces of several feet.


6 pairs of 2 inch pipe could give 30 ma, 1 foot gave me 15 ma ;0)

« Last Edit: February 08, 2007, 03:50:47 PM by americanreman »

asheets

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Re: Salt Water Cells
« Reply #2 on: February 08, 2007, 04:56:45 PM »
I thought the copper and the galvanized pipe were consumables in this reaction.  If so, then this might get pretty expensive to run.  If now, and it is the salt water that is consumable, then I'm moving to Israel and converting the Dead Sea into my own personal battery :)
« Last Edit: February 08, 2007, 04:56:45 PM by asheets »

wdyasq

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Re: Salt Water Cells
« Reply #3 on: February 08, 2007, 05:47:20 PM »
These things should not be called 'batteries'. - They should be called something like 'consumable power supplies'. I would be relcutant to have such a device on a boat except for emergency purposes. Galvonic action can play hell with a boat.


But, it's your cow. You can cook it any way you care.


Ron

« Last Edit: February 08, 2007, 05:47:20 PM by wdyasq »
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americanreman

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Re: Salt Water Cells
« Reply #4 on: February 08, 2007, 06:52:16 PM »
That reaction is bad for a boat, true, but using it as a power supply not part of the boats construction and isolated from other metals would cause no damage to the boat at all..where you run into problems is with outdrives, props, etc. because of the different types of metals used to make a propulsion unit, aluminum, steel for example...or a steel or aluminum boat, a system built into the boat, is filled on deck in a container or that hangs over the side and does not come in contact with these parts would do no harm at all.


I'm not sure but guess that copper and galvanized pipe can last for years submerged in salt water, another thing to consider is draining the system when not in use and filling from the water you are floating in or a storage tank when you need it would greatly extend the life of the metals.


I plan on taking 2 inch sections and hammering them flat or pinching them flat in a vice and filling a square tank to the max with them and see what I get, round pipe seems to be a waste of space having the water just sitting inside them.


2 inches seems to be about the most efficient size of pipe, I think you get loss through the longer sections of pipe as tests so far show that longer pipe is a waste of resource.

« Last Edit: February 08, 2007, 06:52:16 PM by americanreman »

Nothing40

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Re: Salt Water Cells
« Reply #5 on: February 08, 2007, 07:59:10 PM »
I finally found the original thread I was talking about on Google Groups:


http://groups.google.com/group/sci.chem.electrochem.battery/browse_thread/thread/ee8e310568d6360f/11
8cf19cc8549d27?lnk=st&q=saltwater+battery&rnum=17&hl=en#118cf19cc8549d27


Pretty interesting results,could be interesting to experiment with!

« Last Edit: February 08, 2007, 07:59:10 PM by Nothing40 »

RP

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Re: Salt Water Cells
« Reply #6 on: February 08, 2007, 08:27:41 PM »
A few thoughts:


Galvanized pipe will only be effective until the thin layer of zinc is consumed.  You'd do much better with plain zinc as opposed to zinc dipped iron.


On the effectiveness of pipe.  If you really want to use galvanized pipe then size your pipes to be concentric.  Consider a length of 1/2" galvanized inside 1" copper inside 1.5" galvanized.  You can use a few short scraps of appropriate sized PVC pipe to make spacers to keep them spaced off each other.  This will maximize the line of sight surface area.  


It will be better if you can circulate the salt water solution through the pipe to keep the salt solution replenished/flushed.  One simple way to do this is to stand the pipe vertically in the "tank" (completely submerged) and use a aquarium air pump to run bubbles up the gap between the pipes.

« Last Edit: February 08, 2007, 08:27:41 PM by RP »

wdyasq

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Re: Salt Water Cells
« Reply #7 on: February 08, 2007, 08:49:21 PM »
Well, once you have had to replace all the brass, aluminum and stainless below the waterline in an old classic boat, maybe you will have a different opinion. I have done such.


If you think you can 'isolate' by keeping the 'consumable' in a box you think is electrically isolated you may find salt air and the condensation a bit more than you may think. I highly recommend a book or two on 'metal corrosion in boats'. I looked for my copy but it must have been one of those destroyed in the last flood I had.


I lived on a boat for years. I found a lot of 'exspurts' who could tell one just how to rig a sailboat for any conditions. They had expertiece in all kinds of things about boats. The largest majority of them did more sailing sitting on a barstool and in their dreams than anywhere else. Optimist racing sailors actually had more miles than many of these expurts.


Like I said, your cow. But, it you find yourself miles from shore and your propshaft shears or a through-hull fails remember how much money you saved in the build your own battery game and rest assured it was worthwhile. And don't call the Coast Guard. It is better some genes leave the pool rather than swim in another generation.


Ron

« Last Edit: February 08, 2007, 08:49:21 PM by wdyasq »
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maker of toys

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Re: Salt Water Cells
« Reply #8 on: February 08, 2007, 10:14:31 PM »
how to sink an ocean going aluminum boat:

(as told to me by a Coastie).


one:  pitch a handful of copper pennies into the bilge.


two: wait about a week.


'nuf said.


(though the gene-pool comment was a little over the top.)


-Dan

« Last Edit: February 08, 2007, 10:14:31 PM by maker of toys »

americanreman

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Re: Salt Water Cells
« Reply #9 on: February 09, 2007, 05:30:11 AM »
Tell me how an isolated electrical circuit is going to eat away at your boat, it would be perfectly safe and cause no corrosion to any part of the vessel if you had a isolated tank full of saltwater and copper, galvanized pipe with no path to the grey water you are floating in. No different than having a lead acid battery on board and safer, less toxic and no fumes that can kill or ignite.


My idea considers draining the tank after use (maybe 4 to 6 hours +) and require just a few gallons of water, reusing that water for long periods of time.


Every boat should have a sacrificial metal attached to the outdrive hardware or the boat itself in certain conditions if you intend to leave the outdrive in the water, outboard manufacturers build them into their units and they are replaceable. There are additional steps you should take to minimize these risks as well, like ground strapping any metal inlets and strainers.


I've been around boats a long time, scratch built large boats and completely restored old basket case chris crafts in the 42 to 50 foot range.


Your points are appreciated, but not applicable to this situation.

« Last Edit: February 09, 2007, 05:30:11 AM by americanreman »

wdyasq

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Re: Salt Water Cells
« Reply #10 on: February 09, 2007, 05:42:25 AM »
I guess you have it all figured out. Good luck,


Ron

« Last Edit: February 09, 2007, 05:42:25 AM by wdyasq »
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DanB

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Re: Salt Water Cells
« Reply #11 on: February 09, 2007, 08:37:53 AM »
Basically I think it could work, but it would be large, impractical and probably expensive.  You're talking of building a very primitive battery there, and the zinc will vanish pretty quickly if you actually draw signficant current from it.  You'd be much better off sticking to normal batteries and a solar panel or something.  It's not a cost effective solution.
« Last Edit: February 09, 2007, 08:37:53 AM by DanB »
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craig110

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Re: Salt Water Cells
« Reply #12 on: February 09, 2007, 08:43:01 AM »
I agree with you: I also don't see how a fully isolated / insulated reaction will cause the boat's hull to corrode.  Galvonic reaction is nothing more than electrical power causing metal to move.  No electrical flow = no galvonic reaction, so if the electrical flow is insulated within the box, there is no current flow to effect the hull.  (Besides, the BP didn't mention using this on a boat but rather for powering pathway lights.)


Now, is this a useful device?  I suspect no, since the output is, as you said, dismal.  Using the initial numbers, you'd need to connect 400 of the 2 inch pairs for each watt that you wanted to get!  It sure looks like fun to play with, though.

« Last Edit: February 09, 2007, 08:43:01 AM by craig110 »

americanreman

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Re: Salt Water Cells
« Reply #13 on: February 09, 2007, 09:54:12 AM »
The more I test different setups the more I see small cells giving the best results, big is expensive and a waste of metal to power ratio.


Honestly the best metal to power ratio I have so far is 1-1/4 deck screw down through the middle of a 1 inch length piece of copper pipe.


And for sure, saying that this could damage a boat is like saying if I park my car next to the boat and leave the radio on the antenna will errode the hull..silly at best.

« Last Edit: February 09, 2007, 09:54:12 AM by americanreman »

americanreman

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Re: Salt Water Cells
« Reply #14 on: February 09, 2007, 10:02:18 AM »
There is no way that doing this would have adverse effects on any part of the boat.
« Last Edit: February 09, 2007, 10:02:18 AM by americanreman »

craig110

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Re: Salt Water Cells
« Reply #15 on: February 09, 2007, 10:47:28 AM »
What??!!??  You actually leave the radio on when your car is parked by the boat?  You better start bailing now.  Sheeze, the next thing you know someone will be so careless as to actually put a radio on the boat.  Yikes.


But, getting back on topic...  Your tests are essentially showing that maximizing the surface areas gives more power and so, of course, something with a large surface area to volume ratio (such as the nail) will give a lot of power per unit of metal.  The downside of this, though, is that the metal corrosion will deplete a highly-efficient configuration faster than one that had excess metal to begin with.  The most metal-efficient layout is sheets of thin metal in close proximity, but it will also corrode to no current the fastest.

« Last Edit: February 09, 2007, 10:47:28 AM by craig110 »

Drives

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Re: Salt Water Cells
« Reply #16 on: February 09, 2007, 10:50:04 AM »
This post is not intended towards anyone in particular, I liked the logic of the expression.


Thanks Ron!

« Last Edit: February 09, 2007, 10:50:04 AM by Drives »

Bruce S

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Re: Salt Water Cells
« Reply #17 on: February 09, 2007, 01:38:23 PM »
All;

  There is a company that makes these type of "generators" as they call them.

Based somewhere up in VA. At 130USD+ I don't have any saltwater close enough to give it a try , and of course they don't show the insides of the unit:--)


They also say to empty the saltwater once you're finished with it so as not to use up the metals.


just google for salt water batteries and they're right there.


IMHO: from what I know talking to my Father-in-law: who is a chemistry proff. he's say's : it is very possible to make one and the metals are indeed available ( he used to teach how to make them) but once cheap power became available it was taken off the course.


The ideas was ( take thin sheets of metal, thick is for long term power not high quick emergency power) pack as many in leaving room for the water to SOAK all of the metal, minus the last two connections let sit just long enough for the ION reaction to begin taking place ~2 - 5mins, depending on how tightly everything is and there you have it. They are not rechargable in the battery sense, but are reusable in that once you have been saved from the ravages of the deep blue, empty the water , check the metals, replace depleated ones, leave dry. And you'll be all set for next emergency.


Hope this helps

If a truely chemical answer from someone holding a PHD in this is needed let me know and I'll have him type it up, I couldn't correctly spell 1/2 the words he was using :-) but did understand the concept.


Cheers

Bruce S

« Last Edit: February 09, 2007, 01:38:23 PM by Bruce S »
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Mungo

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Re: Salt Water Cells
« Reply #18 on: March 20, 2014, 10:33:00 AM »
I was very excited to find this thread (no electrical pun intended) as this is a project in which we are actively engaged.  We're building a pontoon boat (poly, not aluminum pontoons, before anyone gets exercised) which will be electrically driven.  Short range manouvering using the 1 hp (about 755 watt/12v motor) will be via deep cycle cells charged by solar panels, but for longer trips we are trying to build a "big dumb battery" primary cell which could be staged down when not in use.  The battery is composed of 1/2 gal cell containers and uses bundles of copper and aluminum tubing as cathode and anode, respectively, the aluminum being sacrificial.  I'll try to attach some photos if I can, or you can go over to the forum on the grindlebone.org site and see them (please do).  There's also some over at overunity.com under "salt water battery" on the forums.

Before I go on, to get some things out of the way:  This is an experiment.  YES I know getting an outboard would be easier, yes I know I could just expand the deep cycles we have and add more solar panels, yes I know sulphuric acid is a better electrolyte than salt water, yes I know magnesium might be a better anode, yes I know adding sodium hydroxide or another alkaline would probably increase output.  We wanted to see if we could make THIS work, and I'd love the forum's help in doing so.

Thus far we built a single cell (and are collecting materials for the full 24 cell battery) which produced .54 volts up to a maximum of .74 volts using a wick with the cathode (copper) which I guess technically makes it an aluminum-air cell.  We did a month long corrosion test at no load and discovered no voltage variance over the period, which means the cells are relatively stable even in the salt solution when not under load.  In terms of earlier discussions here, agitation or bubbles help maintain the voltage, but I think most of the problem is the accumulation of hydrogen and oxygen bubbles from electrolysis on the electrodes which inhibits the chemical reaction.  Shaking them off restores voltage.  Certainly, cells on a boat would be subject to a degree of native agitation.

So here are my questions:  is there some formula for this to calculate current (amps) and the destruction of the anode?  I have no idea what the amp output of the cells are, but a discussion over on google (https://groups.google.com/forum/#!topic/sci.chem.electrochem.battery/7o4xBWjWNg8) seems to indicate a rather higher output than I'd considered. 

Would love to hear suggests, ideas, rants, vents, and brilliant solutions from the board

(btw the multiple leads coming off the cathode were an attempt to drive a tiny motor with the cell and have nothing to do with the voltage reading)
« Last Edit: March 20, 2014, 10:41:26 AM by Mungo »

Mungo

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Re: Salt Water Cells
« Reply #19 on: March 20, 2014, 05:22:15 PM »
As an interesting side note, this '60s patent battery uses steel wool and a magnesium core with salt water.  Fairly impressive current flow.

https://www.google.com/patents/US3401063