Test of aluplate<->sand-graphite-tablesalt battery cell

[gast]

Stefan, thank you for the links.

>> Do you think it should be pulsed DC or just only DC current ?

If you have the possibilities try both. I would test plain DC first. Good success!

Regards Gast

[hartiberlin]

Well I had a curious thing happening today.

As I came back to the plate this morning, there was some black
slurry gasing out of a few holes in the graphite paste mix
and some black surry water droplets formed on the surface.

The black surry had a NEGATIVE voltage ( about - 0.1 Volt) versus the alu plate)
compared to the rest of the
black mix, which still had around 0.4 Volts versus the aluplate? !

Hmm, I then heated the plate again on the oven? until all
water was gone and evapourated.
The gasing out of the holes was then
accelerating... so there must have been some
kind of chemical reaction been going on...

Pretty strange that it just started only 2 days after I made the
plate with the mix on the top... Hmm...

Then there was no voltage left and also no current
( still in a heated temperature)

Then when the temperature had dropped 30 minutes later to
room temperature, there is again about 0.3 Volts and 2.5 mA available.

Maybe the mix sucks in water from the air and thus can again
generate a galvanic? process ?

Regards, Stefan.

[Walter Hofmann]

Hi gast,
yes I did try prety much al kind of external power AC up to 40Khz and DC also current up to 6 Amp, what is happening is that the cells then work like a capacitor and you can use the amount charged but no more comes out and the cell does not generate the same amount of power then without the charging. On the contrary if the cells are short circuit at the start up in specific intervalls the cell will perform a much higher and longer lasting output. The most importand part is that the alu or alloy is insulated from the graphite in order to get the most current out the insulation increases the current up to 100%. to insulate alu you can use a chemical version where on the alu plate is a kind of honey comb oxide created what insulates the plate totally but the graphit will go in to alle the tiny cave's.
greetings
walt

Sorry Stefan, but what is "zamak alloy"? Alloy = "legierung", but zamak... I don't know.

>> When I applied the heat from the oven and shortcircuited the cell
>> during heating, the current did rise and afterwards had a bigger value,
Hm, shortcutting the cell will result in a current with an max amount which the cell is able to produce at this moment.
So if the cell is low on power it will result in an lower current for the forming-process.
Did Walter Hofmann (or you) test the forming process using a higher current provide by an external power source?

Regards Gast

[Walter Hofmann]

Hi stefan,
yes I did have the phenomen with the black slurry droplets to, it is a combination of chemical reaction, the electrical short build by direct applying the graphit on to the surface of the alu plate and the air. I have seen this only if the hole setup is not enclosed the same thing happening if the graphite is to moist then the water will be drawn to the surface and build sometimes even a hole layer of water what is then dangerous to the contact material.
further it is importand the use a cantact plate for the connection to the graphite bedcause without you only pick up what the leadtip surface can take what is not much thats why you only get the smale amount of current. with your setup size you should get at least 0.8V open circuit and 80 to 100 mA short circuit.
That the process startet only 2 days after the initial setup is common if you remeber my first couple tests because thats the initial priming process sometimes it takes up to 5 days and this is what you can shorten with the intervall short and after this the hole cell will settle to the final output value.
The accelerating of the gases comes from the direct connection of the graphite and is a mix of hydrogen and chlor gases pretty much the same thing what you can experience with the setup in a glas with saltsolution a alu or alloy rod and a graphite rod and applying external charge.
Further depends the graphit sand mixture on the kind of sand what you are using because there are many diffferent typ's of sand the simplest test is to take some put it on a moist sponge and polish a piece of alu if you got deep scratches the sand is hard ( its called sharp sand) and will not work as well as soft sand ( like beach sand) and then there is the question what impurities in what amount the sand holds.
greetings
walt

Well I had a curious thing happening today.

As I came back to the plate this morning, there was some black
slurry gasing out of a few holes in the graphite paste mix
and some black surry water droplets formed on the surface.

The black surry had a NEGATIVE voltage ( about - 0.1 Volt) versus the alu plate)
compared to the rest of the
black mix, which still had around 0.4 Volts versus the aluplate? !

Hmm, I then heated the plate again on the oven? until all
water was gone and evapourated.
The gasing out of the holes was then
accelerating... so there must have been some
kind of chemical reaction been going on...

Pretty strange that it just started only 2 days after I made the
plate with the mix on the top... Hmm...

Then there was no voltage left and also no current
( still in a heated temperature)

Then when the temperature had dropped 30 minutes later to
room temperature, there is again about 0.3 Volts and 2.5 mA available.

Maybe the mix sucks in water from the air and thus can again
generate a galvanic? process ?

Regards, Stefan.

[hartiberlin]

Have a look here.
Directly uploaded via mobile phone via MMS.
When we will have the mail2SMF function, I could
post directly over here the pics via mobile phone,
but the mail2SMF function is not yet ready, so go here:

http://phlog.net/user/harti