This gonna be short and simple instruction for making a Galvanic cell and battery from some normal wood screws or Nails or any other similar material and copper wire and some tissues and stickies and using the battery to power an LED. the principle is simple and 1st time discovered in 1780 by Luigi Galvani in the famous Frog leg experiment :) if you like to know more about it check wiki: https://en.wikipedia.org/wiki/Galvanic_cell
Step 1: Ingredients!
You need this material:
- Some galvanized screws or nails each screw is one cell and each cell produce about 0.7 volts, so do your maths and calculate how many you need. for one red LED, you need at least 3 of them.
- 2-3 meters of fine uncoated copper wire. you can get some from stripping a power cord.
- some tissues finer is the better.
- sticky tape to keep the electrolyte (moisture) inside the cell.
- you need to wet the cells to start the chemical reaction at the end with some kind of electrolyte like Tap water, salt water, vinegar or wee-wee! just use your imagination!
Attach some copper wire to the end of screws or nails. this going to be your negative terminal! don't full by the end of Philips screws shape! its look like positive. but believe ,me it going to be the negative terminal.
roll the screw inside a thin layer of tissue. the tissues purpose is to separate Anode (The screw) from the cathode (Cooper wire) the finest and less layer is the better it give you more current and juice. but there is a very good chance of copper wires breaking through the very thin tissue and shorten the cell.
now start winding the fine wire on top of the tissue. don't press too hard to prevent puncturing tissue. remember they going to get wet! for more juice (current/ mAmp) you can add one more layer of tissue and copper and after that more layers don't change the maximum current anymore. remember the voltage is always around .7 volt but the current can differ from .5 mA to 13mA per 1 screw cell!
it is almost done. if you have a multimeter you can check the cell if it shorten internally or not. a dry cell should show a very large resistant (R = infinity Mohms) very low voltage and current (near zero)
if the resistance is zero or near zero, the cell is shorten and you have to start over.
now add your electrolyte. you can soak the cell in tap water. tap water is fine and it should be good enough for 1 LED. I tried many different electrolyte and the stronger the electrolyte the higher the maximum current, but it is shorten the life of your battery. so if you need higher current (my record is 12.5 mA per cell) use salt water. I found the salt water the best then vinegar is the second, and lemon juice third and tap water is last one.
basically the higher the current, faster the corrosion and faster you lose the zinc coating your battery dies faster.
in last picture you can compare a fresh screw(zinc coated anode) with a 2 days old anode.
at the end you need to put your cells in Series or in parallel for a desirable out voltage and maximum current.
there is an Instructable about how to wire batteries in series and parallel:
and if you like to know more about how to connect your battery to LED, you can check this one:
I don't know what is the limit of maximum voltage and/or current, but I'm wondering if you assemble enough of them to start your car!