Quote from: DrZoidberg on June 24, 2010, 02:05:27 PM
...
Is your aluminum coated with plastic?
BTW. You can increase the voltage to 1.4V by adding a tiny amount of NaOH (drain cleaner). But it will dissolve the aluminum. The more you put in, the higher the load can be before the voltage drops but the aluminum will dissolve more quickly.
Don't put a large amount of NaOH in. It will bubble like crazy and can get quite hot.

And it will be producing H₂ gas when it dissolves the Al. So, be careful with any flames if you get a lot of bubbles.


@conrad,
I like the cement idea. I found it worked for a while myself, and perhaps you have found the trick to keep it active.
the alkaline neture of the cement is what makes the H₂ gas form and it does this with magnesium too. I am wondering if this "air battery" that Lasersaber has described might not work for a longer time if cement is placed between the mag ribbon and the copper pipe or carbon rod.
I may mix up some cement soon and try this.

Once the cement is mostly dry and not so actively alkaline, it might be a great interface material, but before it dries it will not, IMO.

Quote from: knovos on June 23, 2010, 05:08:20 PM
I have been playing for a week with this stuff and what I see there is a oxidation going on by the water with some kitchen salt on the magnesium ribbon (see pictures down under)

BTW
Welcome and thanks for the pix
ugly!
You have inspired todays tests. 

I am testing a couple of electrolytes today.
I used epsom salt the other day and I am not seeing the kind of degradation that others who have used table salt have.
So, I will see what happens and let you all know.

jeanna

I have some preliminary pix of the difference between NaCl and MgSO₄ as electrolyte.

Just so you know what I did, I measured off equal amounts of mag ribbon and copper wire, made a spiral of each which I hung over the edge of the glass. I had to wrap the copper with something to prevent contact, so I used some gauze.
The solutions are approximate and they should both be saturated solutions which means there is a little undissolved salt in the bottom of the glass.
The refined sea salt = NaCl gave a voltage/amps reading of
1.49v
27mA

The epsom salts = MgSO₄ gave a reading of
1.58v
20mA

They started at very close to the same time, but as you can see, there are way more bubbles on the Mg ribbon in the NaCl than in the MgSO₄

They are big, but they pop the way H₂ pops but there is no orange color at the point of the flame.??

Have a look.
First is the NaCl second is the MgSO₄

jeanna

I just realized that it was dumb and risky to pop the bubbles with a flame so very close to the magnesium ribbon.
Please don't do this yourselves anybody...you may not be as lucky as I!!

Nice work everyone, I've been busy for a few days, it's nice to see everyone contributing and forging ahead.

@Conrad,
I really like the design of those aluminum and copper cells, really great job. I agree that something seems to be leaving the cell that diminishes the power, not sure if its the oxygen that's being depleted, it might also be the hydrogen also as it appears in Jeanna's test of different electrolytes. Keep up the good work Conrad we'll figure it out.

@Jeanna,
Nice job on the electrolyte tests. This is very useful information to know. Just one question, what's the time frame on those pictures?

@All,
I have also made a recent update on my air batteries to show they're all still alive and still performing well. Also it's my first video upload, so it's a test on that as well. It's broken into two parts, my camera was giving me some difficulties so it cut off towards the end of the first video.
Part 1 http://www.youtube.com/watch?v=1Hc-xyTFFGk
Part 2 http://www.youtube.com/watch?v=eLry46yKcmI

Hopefully I'll finish the new ones I'm working on this weekend, I'll be sure to keep you guys(and gal ) posted. Once again keep up the good work to everyone and thanks for sharing the info.

-Pete

@DrZoidberg

QuoteStrange. Even a small copper coin and a small piece of aluminum foil give 2ma, so your initial current should be a lot higher then that.
Is your aluminum coated with plastic?

When I fill the tube with "fresh" saltwater (the concentration of salt does not matter, equal or more than seawater concentration which is 3.5%) I get a very high current (up to 20 mA) for a short time (some minutes), for up to one hours I get up to 2 mA and then it drops to 0.04 mA. (Aluminium - salt water - copper in the test tube, as in the photos I posted above).

The aluminum sheet from the soft drink cans has been scrapped on both sides with sand paper (with a hand held machine) till only raw aluminum is visible.

Greetings, Conrad

@ Pete (PeteIdl4), Jeanna and all

Great videos, Pete! Carbon and magnesium seem to be the best; also in combination with copper, and carbon - magnesium seems to be top. The little carbon - magnesium cell is surprising.

Because adding water (as Pete shows in his video) helps and as Jeanna shows in here water containers, magnesium and copper also work great in a "wet cell".

I wounder what keeps aluminum in my test tube cells from reacting long term (not only for a short time after filling the tubes with fresh salt water)? It can not be the copper, because Jeanna uses copper in her wet experiment with magnesium ribbon.

May be aluminum is just not as active as magnesium. Magnesium is almost as fast as sodium (Natrium), therefore it deteriorates rather fast (pieces breaking off).


Bagdad Battery

I also did some tests with a Baghdad Battery (see http://en.wikipedia.org/wiki/Baghdad_Battery ) which simply means I used citric acid instead of salt in my test tubes.

With aluminium and copper (in the test tubes) citric acid gives about the same results as salt (impressive for a few minutes, pretty good for an hour, but then amperage drops like in salt water to less than 0.1 mA). Different concentrations of citric acid did not help.

I plan to make a real Baghdad Battery with iron and copper (and citric acid). May be iron reacts better than aluminum (although it will give a lower voltage).

When I think about it, steel or iron rusts (corrodes) much faster in seawater than aluminum, or am I mistaken?


Tile cement cell

I did not give up the tile cement and will build more and bigger tile cement cells after my excursion into wet cells comes to an end. The aluminum - tile cement - copper cell serves as a reference (which I could not yet beat with a wet cell).

I know that magnesium and carbon beats everything, but I want to exploit readily available materials (like aluminum, steel and copper) first. And only when that becomes hopeless I switch to the super stuff (which will not be available in an crisis situation). Salt and citric acid are rather easy to get (seawater and many fruits).


Seawater

I really like seawater (saltwater), if one can use that, it would become simple. Even with a bulky set up, it would be great as an emergency battery.

O.k., I make a steel - saltwater - copper thing right now, stay tuned. I will wrap one metal in a cloth as Jeanna did, then the build stays simple.


Greetings, Conrad