Graphite-Paper - Aluminium-Foil galvanic cell with 1.7 to 1.92 Volts

[stephenafreter]

Hello,
A quick update on my aluminium battery.
I put two silver electrodes with 2 pieces of aluminium foil in water with salt and NaOH to see what it does. So it's 2 cells in series.
This first trial gives less power than 1 silver/magnesium ribbon cell.
So I have many things to modify after this first trial.
I want to reproduce the experiment by the Hong Kong student in the file given by Mk1.
NaOH is eating the aluminium slowly, hydrogen bubbles evolve in the liquid.
After just a few minutes the light goes down, and if I shake a bit the cells, light comes back for a few seconds. I am really far from the results in the Hong Kong experiment 
I will keep you informed. I am waiting for graphite pencils to make electrodes as in the pdf.
Now I am using a bifilar from a Bedini setup to make a more efficient Joule Thief. I still don't have a toroid.

[hartiberlin]

Hi Stephen,
good experiments.

Well, does anyone have an idea how to
best press graphite powder directly onto stainlesss steel mesh ?

What press could I use to do this easily ?

I would need to press about 10 x 10 cm area
graphite powder directly onto a stainlesss steel mesh,
that is also around 10 x 10 cm big in surface area.

This way using no binder, you will have the best and lowest resistance
and the stainless steel mesh will push up the amps from your battery
and lower the electrode resistance.

So I need to find a good solution to this,
so that I could do this at home with some easy
obtainable tools.
I would need to have about 1 mm height below and above
the stainless steel mesh of pressed graphite powder ( Lampblack for instance).

Any good ideas to do this ?
Maybe also just 2 x 50 cm size will work, so I would only
need a pressing width of 2 cm ? ( and then do several compression pressing steps to
achive the 50 cm length ? 2 cm x 50 cm would also be 100 square cm )

Of course it depends how good the graphite will stay on the stainless steel
mesh after several usages and does not come loose from it, when you wash
the electrodes after several usage cycles.. so maybe the acryllic binder
method is stll the preferred method for longer usage cycles ?


Regards, Stefan.

[stephenafreter]

Hello Stefan,
I read on wikipedia that they use to bake the graphite/clay mix to make the pencils.
http://en.wikipedia.org/wiki/Pencil
Extracts:
- Most pencil cores are made of graphite mixed with a clay binder.
- Residual graphite from a pencil stick is not poisonous, and graphite is harmless if consumed.
- mixing powdered graphite with clay and forming the mixture into rods that were then fired in a kiln. By varying the ratio of graphite to clay, the hardness of the graphite rod could also be varied.

I thought they were just pressing the powder into forms, but it needs to be fired to get the best material ... making things more difficult.

[hartiberlin]

Well,
it might be good for pencils,
but as the clay is nonconductive, it will have  more ohmical resistance probably.

Maybe you can measure the ohmical resistance with these pencils and let us know ?

Many thanks.


Regards, Stefan.

[stephenafreter]

Hi Stefan,
Resistance on my graphite pencils are around 20 Ohms.
While the best I could get with graphite powder + binder, was around 10 to 15 kilo Ohms !
That's 1,000 folds the resistance of the industrial pencils (those that are baked with clay).
Hope this helps.