off topic but questions about battery plates materials

[werowance]

so not long ago i found the reminants from an old science project i did with my grand kids. making a battery from potatoes using an iron nail and a galvanized nail and it got me to thinking about using a little more profesional looking plates and such, maybe experiment with lemon juice, viniger and other less dangerous acids to see what results could be obtained. but then the question hit me, what about plate materials.

i do have some galvanized coated material but once cut and machined into nice plates i would lose alot of that material. iron is readily available.

but what about a mix of copper and lead (lead would be less child friendly but this is an adult science project) or iron and copper etc... what would be a good combination of materials for the plates that might be found in a home shop? i have lead, copper, 360 brass, aluminum of different alloys, cast iron, steel and stainless steel are pretty much my readily available things.

i am aware of the gasseous dangers of most acid batteries and ignighting the hydrogen coming off from them. i will treat any testing i do as poisonous to breathe and explosive as i experiment. i have had a lawn mower battery explode in my face many years ago as i was boosting it and i will never forget that experience.

 

[wgpeters]

Look at the table of standard electrode potentials. This will give you an idea of what voltages to expect from different metals. For example:
A copper (Cu) electrode has a potential of about +.52 volts.
A zinc (Zn) electrode has a potential of about -.76 volts.
Together, with an appropriate electrolyte should give a voltage near 1.28 volts with the zinc electrode being negative.

 

[werowance]

Thank you wgpeters, that just opened a whole lot of information for me.

i did a little testing last night, and it appears copper and galvanized sheet metal were the best combination giving .9 volts but it had the greatest reaction and the galvanized (i guess zinc) was copper plated very quickly. copper/lead gave the least amount of fizz or reaction and gave .6 volts, copper/aluminum gave .6 volts with some fizzing and .45 volts from Lead/Aluminum. so looks like copper/zinc is the winner from what materials i have. i might try copper/iron tonight

 

[werowance]

so now my next question is this, im thinking it would still be 1 volt from what im reading (using 1 volt just as an easy math. i really only got .9 volts) or would the bottom example produce more volts? im thinking not and i would have to run seperate batteries in series to get higher volts right?

 

[wgpeters]

Current capacity depends on surface area of electrodes.

Voltage depends on electrode materials, and choice of electrolyte(s).

In operation, the zinc will oxidize creating a zinc salt which dissolves into the electrolyte.
EG: if using sulfuric acid as the electrolyte, zinc sulfate will be produced.
If table salt were used as electrolyte, the zinc would produce zinc chloride.

A better choice of electrolyte might be copper sulfate.
As the cell is used, copper would plate onto the copper electrode for a while. But production of zinc sulfate will replace the copper sulfate eventually killing the cell.

If you separate the two halves of the cell with a porous separator and use zinc sulfate on the zinc side and copper sulfate on the copper side, the separator will keep the zinc sulfate from mixing with the copper sulfate on the copper side and plating zinc on the copper. This will give the cell a much longer life.

BTW, the standard electrode potentials were measured using a 1 molar solution of electrolyte.
To calculate the 1 molar solutions, you have to look up the atomic weights for the components of the molecule, add them together, and use that many grams to make a liter of solution.

EX: Copper sulfate = CuSO4 is about 160 grams.
Zinc sulfate = ZnSO4 is about 161 grams.

 

[werowance]

ok, copper sulfate isnt something i would have in the shop (unless its labled and sold as something else like epson salt or something).. i do have regular battery acid (sulfuric acid)for filling tractor batteries and such, i read about bleach water as well as salt water for a more safe solution.

i may just go the easy route, copper and aluminum with a bleach water electrolyte, what do you think? or any suggestions on a decent combination that one might have available in the shop? id kinda like to hit the 6 volt area or near that as i have a pack of 6 volt head light bulbs for my old farmall tractor in the tool box that ill use with the battery.

started modeling a case for it that ill use my 3d printer to make. im using free cad, and learning as i go on that

 

[wgpeters]

Be careful, and test your combinations outdoors until you are sure that you are not going to produce any dangerous fumes.

 

[nel2lar]

It is always good to work in a ventilated area. Some fumes produced in mixing products making unknown toxic fumes.
Be very careful.
Nelson

 

[RM-MN]

ok, copper sulfate isnt something i would have in the shop (unless its labled and sold as something else like epson salt or something).. i do have regular battery acid (sulfuric acid)for filling tractor batteries and such, i read about bleach water as well as salt water for a more safe solution.

i may just go the easy route, copper and aluminum with a bleach water electrolyte, what do you think? or any suggestions on a decent combination that one might have available in the shop? id kinda like to hit the 6 volt area or near that as i have a pack of 6 volt head light bulbs for my old farmall tractor in the tool box that ill use with the battery.

started modeling a case for it that ill use my 3d printer to make. im using free cad, and learning as i go on that
View attachment 103883

Copper sulphate used to go by the name, "blue vitriol".

 

[werowance]

yep I have been testing out doors, and with face shield, full sleeves, welding apron and gloves. I to was concerned about fumes, especially on the galvanized test because I know of the dangers of welding it so I figure its possible for it to make cyanide gas when its getting oxidized by the electrolyte or something. and then the thought of bleach water making chlorine gas as well. so yes outside and the kitty cats secured inside the house and all so no accidental animal or human harm. and then we all know what hydrogen or browns gas does....go boom.. when introduced to a spark so no smokeing for me while working on it as well. and on the case, the lid will be vented as well. really not looking to store the electrolyte in the battery for long term on a shelf or anything. just long enough to say that I did it then drain it out and clean with water before putting up on the shelf and forgotten.

what is blue vitriol? or what was it used for?

 

[Chris Murphy]

yep I have been testing out doors, and with face shield, full sleeves, welding apron and gloves. I to was concerned about fumes, especially on the galvanized test because I know of the dangers of welding it so I figure its possible for it to make cyanide gas when its getting oxidized by the electrolyte or something. and then the thought of bleach water making chlorine gas as well. so yes outside and the kitty cats secured inside the house and all so no accidental animal or human harm. and then we all know what hydrogen or browns gas does....go boom.. when introduced to a spark so no smokeing for me while working on it as well. and on the case, the lid will be vented as well. really not looking to store the electrolyte in the battery for long term on a shelf or anything. just long enough to say that I did it then drain it out and clean with water before putting up on the shelf and forgotten.

what is blue vitriol? or what was it used for?

Wearing my chemist's hat this time-'oil of vitriol' is an old fashioned name for sulphuric acid-so some common salts of suphuric acid were knwn as 'xyz vitriol' or by the colour-in this casev copper sulphate is a bright blue-so 'blue vitriol'. There are all sorts of quaint names out there still in occasional or regional use for various chemic. als-including such oddities as 'sugar of lead' [aka 'salt of Saturn' !] which is lead acetate. Copper sulphate can quite often be found at plant shops-in the fertiliser section-along with quite a few other common chemicals in 'pure' form....by 'pure' in this context I mean as the single compound, not a mixture of chemicals. It is probably the lowest grade of purity in terms of chemical purity by analytical assay-but perfectly usable for this sort of work-or for home copper plating-which is probably the major use for it industrially.

 

[RM-MN]

About 60 some years ago I believe the copper sulphate was used on our farm to dip the sheep to clean the skin of bacteria and/or fungus. It was mixed in water and the sheep were forced to jump into the solution, then helped out at the other end of the tank.