[Cap-Couillon]

Theoretical discussion.... Although I am gonna have to try it just to find out.

Small sail-far cruiser. No room for genny so using all led lighting, no powered reefer, etc. Lead acid wet cells, solar panels, and 5A light coil on the kicker are primary power system.

What to do a gajillion miles from no where, and the batteries go flat, the kicker is out of gas, and we haven't seen the sun in 12 days...

Lets see, the potential difference between a piece of bronze, and an aluminum/zinc/iridium sacrificial anode is (theoretical) 0.8V in saltwater, so if we made up a single cell consisting of an aluminum "zinc" and say a bronze bolt, and hung it over the side it should generate 0.8V. A set of 15 in series would generate 12V... See where I am going with this? Not enough to fuss with normally, but in an emergency maybe enough to keep the LED nav lights and the non-plotting digital gps running till the normal system is back on line.

Just an interesting thought brought up while reading a non related article on a non-boating site. They were using thin copper and magnesium strips in fresh water to light a single led.

Comments? ideas? horse-laughs? Might be fun to try... now where did I stash those extra zincs for the kicker?

 

[Barquito]

Sounds like we need the professor from Gilligan's Island. Personally, I think electricity is over-rated.

 

[newhaul]

Problem is Russell Johnson died last January on Bainbridge island

Here's one of the projects I found when I googled how to make a saltwater battery
Air Battery or Saltwater battery

 

[DonScribner]

How about a Peltier generator sitting in the sun with a hose and a venturi valve sucking cold water thought the cold side as you're moving?

 

[newhaul]

There is something that will cost about the same and puts out more power http://www.usawindgen.com/50.html

 

[travellerw]

You may be able to generate some voltage, but the current you could draw would be very low.

There used to be a very cool show called "Rough Science" where scientists would use their skills in different survival situations...

Anyway, in one of the shows, they do a "Man overboard" scenario. They created a salt water battery using an ice cube tray, some sponges and 2 dissimilar metals (don't remember what the metals were), attached to a single LED. The device was then strapped to the person that was thrown overboard. Once dunked in the salt water, the battery became active. Although the LED did light, it was very DIM.

Personally.. You might be able to make a battery to provide a little light from a few LEDs, but that would be about it.

 

[Cap-Couillon]

There is something that will cost about the same and puts out more power

Looks like a fun toy, and the price is certainly reasonable... But with all plastic parts and the disclaimer of "Intermittent use Only" I don't think it would live long enough on the boat to be worth the cost? If I ever get 80 bucks with nothing better to do, I might get one just for the fool of it

You may be able to generate some voltage, but the current you could draw would be very low.

.
I do believe (but I have been wrong before) that increased draw (current) will just eat the anode faster. Twice the current draw will consume the "zinc" twice as fast. How fast that is remains to be seen.

The problem as I see it is creating enough "cells" to get up to the normal operating voltage of my nav lights (12V). They have built in ballast resistors to limit the current to 2.5mA / led at about 2V forward voltage. At 12V (nominal) they draw around 150mA (0.15A) each plus the GPS (Garmin 126) draws 80mA. So we need a total of 530mA (port, stbd, stern, nav lights plus GPS) to run the bare essentials.

Haven't found a good source to relate current to anode consumption. Most of my numbers have come from http://www.performancemetals.com/images/pdfs/Aluminum%20Anodes.pdf which tells me the aluminum anode will be consumed 30-50% faster than a zinc anode, but the higher voltage might make it a better choice. With a bronze cathode, we would need 16 cells with zinc anodes, and 15 cells with aluminum anodes. ???

Just gonna have to try it out

 

[Multihullgirl]

just stick your metals into lemons. Cure scurvy and get power.

 

[Cap-Couillon]

Need the limóns for the rum!

 

[newhaul]

They make bigger ones at costs of less than a buck a watt ( 250 watt for 225 includes USA shipping).

 

[hellosailor]

Wouldn't it be simpler, cheaper, faster, to just buy and stow some spare power source? A dedicated AGM battery in a locker? A hand crank set? A methanol power cell and a jug? If you are planning ahead, you know, just make the plans and buy the spare. Or consider, very little on a sailboat really REQUIRES electricity for any necessary function, does it?

 

[Cap-Couillon]

Oh there are many more practical solutions to the stated issue, I am sure.

I was just sort of intrigued with the idea of sticking a bunch of bronze bolts and pencil zincs in a piece of starboard, heaving it over the side and generating enough power for a few days (nights) of nav lights and gps.

Haul it out and rinse it off, let dry and use again till the zincs are gone.

Just my (slightly) twisted mind at work.

 

[TakeFive]

Oh there are many more practical solutions to the stated issue, I am sure.

I was just sort of intrigued with the idea of sticking a bunch of bronze bolts and pencil zincs in a piece of starboard, heaving it over the side and generating enough power for a few days (nights) of nav lights and gps.

Haul it out and rinse it off, let dry and use again till the zincs are gone.

Just my (slightly) twisted mind at work.

There are so many reasons that this wouldn't work, including the tiny current generated.

But forgetting all that, you could never just "heave it over the side." To get to 12v, you would need each cell to be insulated from the others, and then connect them in series. So you would need 15 separate plastic buckets of salt water, each one with an anode and cathode...just like the 6 separate cells in a normal lead acid battery.

 

[newhaul]

There are so many reasons that this wouldn't work, including the tiny current generated.

But forgetting all that, you could never just "heave it over the side." To get to 12v, you would need each cell to be insulated from the others, and then connect them in series. So you would need 15 separate plastic buckets of salt water, each one with an anode and cathode...just like the 6 separate cells in a normal lead acid battery.

Or plastic ice'trays

 

[WGEwald]

Problem is Russell Johnson died last January on Bainbridge island

Here's one of the projects I found when I googled how to make a saltwater battery
Air Battery or Saltwater battery

 

[davidpm]

Great entertainment but since you have to prepare in advance anyway just throw one of these in a locker and be good to go.

Solar Brand SOLES5000 Car Battery Booster Jump Box 1500 Peak Amps | Battery Jump Boxes / Jumper Cables

When I do deliveries and I have a car ride both directions and have any doubts about the boat batteries I usually bring my booster just in case.

 

[hellosailor]

First, you net some minnows

First, you net some minnows. Then you use them as baitfish to catch some larger fish. And some larger fish. And then you go to the rocks where the electric eels have their lair.

Voila, coupla thousand volts all day all night until you run out of fish to feed them.

Who needs to mess around with metalware and scrap parts to make electricity?

 

[wristwister]

Sounds like you basically described a battery minus the plastic case. Wouldn't it be simpler to just carry ... a battery?

Besides, I've got a much better solution for you. I just plug my charger into the inverter to keep the batteries topped up.