Content

• Method 2 of 3: Battery of three potatoes
• Method 3 of 3: Troubleshooting
• Warnings

1 Gather the required materials. Before you start assembling a watch on a potato battery, you should prepare everything you need.Most of the materials (with the exception of potatoes) are likely to be purchased successfully from a hardware store. For potatoes, you will need to go to the grocery store. Prepare:

• 2 potatoes;
• 2 copper rods (copper wire);
• 2 zinc rods (galvanized nails);
• 3 wires with crocodile connectors (each wire connects a pair of clips);
• simple electronic clock with low voltage requirements.

2 Remove the batteries from the electronic clock. This project will allow you to power the watch not from batteries, but from a potato battery, which you connect to the contacts (“+” and “-”) of the battery compartment of the watch. Set the battery cover temporarily aside so that you can easily reach the corresponding terminals with the wires.

• If the terminals in the battery compartment are not labeled with “+” and “-” signs, do it yourself based on the actual location of the batteries using a permanent marker.
• If the terminals are signed, then positive will be marked with a “+” and negative with a “-“.

3 Insert one nail and one small piece of copper wire into each potato. First, number the potatoes for yourself as 1st and 2nd. This will help you differentiate between them later in the experiment. Then insert one nail at one end into each potato to a depth of about 2.5 cm. After securing the nails, stick a piece of copper wire into the opposite ends of the potatoes at the maximum possible distance from the nails.

• Each potato should have a nail sticking out on one side, and a copper wire on the opposite side.
• Make sure the nail and wire are not touching inside the potato.

4 Connect the potatoes to the clock using the wires with crocodile clips. Using three wires with crocodile terminals, first connect two potatoes together, and then connect them to the clock. This will allow you to assemble a closed electrical circuit through which current will flow. Assemble the chain according to the instructions below.

• Connect the copper wire of the 1st potato to the positive (“+”) terminal of the watch's battery compartment using the first crocodile wire.
• Use the second wire to connect the nail of the 2nd potato to the negative terminal (“-”) of the battery compartment.
• Use the third crocodile wire to connect the nail of the 1st potato and the copper wire of the 2nd potato.

5 Check the connection and set the clock. As soon as you complete the circuit with the third crocodile wire, the clock should start working. If this does not happen, check the reliability of all connections so that the metal is firmly in contact with the metal everywhere.

• The resulting battery will not last very long, so it is wise to disconnect the battery after testing it if you want to showcase your watch at a science project fair or just show it to your class.

Method 2 of 3: Battery of three potatoes

1. 1 Start by preparing your materials. As with most experiments, you should start by preparing the materials you need to get started. Most of these can be purchased at the hardware store, and some of the materials may already be in your home. Prepare the following:
   • 3 potatoes;
   • 3 copper plates (you can use copper coins of the USSR);
   • 3 galvanized nails;
   • 5 wires with crocodile clips at the ends (10 clips in total);
   • 1 clock with low voltage requirements.
2. 2 Place a nail in each potato. As with the battery of two potatoes, one galvanized nail should be inserted into each tuber. Attach a nail to one end of the potato and press in about 1 inch (2.5 cm). Repeat this step for all the potatoes.
   • Make sure that the nail does not come out from the back of the potato.
   • Make sure that the stuck nail will not touch the copper plate or the coin you will insert next.
3. 3 Insert one copper plate or coin into each potato. Press a copper plate or coin into each potato from the opposite end of the nail. If you are using a coin, make sure half of the coin remains visible above the surface of the potato so that you can connect the alligator terminal to it in the following steps.
   • If you have taken copper strips, make sure that they do not get too deep in the potatoes and do not touch the nails because of this.
   • Try to place the galvanized nail and copper in each potato as far apart as possible.
4. 4 Collect the potatoes in a serial connection. Once each potato has a galvanized nail and a copper plate at different ends, they can be daisy-chained together to generate more electricity. Place the potatoes in a row in front of you and use the wires with alligator terminals to daisy chain them. Make sure all the potatoes are oriented the same way, that is, the nails point one way and the copper plates the other.
   • Attach the wire with one clamp to the copper contact of one potato, and with the second clamp, attach it to the nail of the next.
   • Repeat the action with the next potato to get three potatoes in a row, the two outermost of which will be connected with one wire to the central potato.
5. 5 Connect the potatoes to the clock. The two outermost potatoes will be connected to the center potato with only one of their wires. Now you need to connect the remaining two wires as follows: one to the free nail of one extreme potato, and the other to the free copper contact of the other extreme potato.
   • Connect the outermost wire that is connected to the nail to the negative terminal of the watch's battery compartment.
   • Connect the outermost wire that is connected to the copper terminal to the positive terminal of the battery compartment.
6. 6 Check all connection points and turn on the watch. As soon as the last two clips are on the positive and negative terminals of the battery compartment, the watch should turn on. If this does not happen, check the tightness of all connections to ensure good metal-to-metal contact.
   • The clock will start when the circuit is securely connected.
   • If you want to demonstrate your experiment at a school scientific conference or in class, it is wise to disconnect the clock from the potato battery after checking, so as not to waste its chemical energy ahead of time.

Method 3 of 3: Troubleshooting

1. 1 Check the wire pins. If your watch won't turn on, the problem might be a broken circuit between the potatoes or potatoes themselves and the clock. Make sure each connection is secure and no other material gets wedged between alligator clips and galvanized nails or copper plates. You should also check the correctness of the serial connection: all wires between the potatoes should connect the positive contacts to the negative ones. In other words, the nail of one potato should be connected to the copper pin of the next potato, and so on.
   • If you've used copper coins, try replacing them with copper plates to ensure a more reliable connection between the pins.
   • Make sure each clip is firmly in place and not touching the potato itself.
2. 2 Add another potato to the chain. If the circuit is assembled correctly and reliably, but the clock does not work, it is possible that the potatoes are giving out too low a voltage (voltage) to power the clock. To check the voltage of a potato battery, you can use a multimeter or voltmeter (if you have these), or you can simply try adding another potato to the battery to increase its power.
   • Add another potato to the battery in the same way as you connected all the other potatoes: connect the wire from the copper contact of one potato to the galvanized nail of the next, then another wire from the copper contact of the last potato to the clock or to the next potato.
   • If the extra potato doesn't make the clock work, then the problem is the connection or the clock itself.
3. 3 Soak potatoes in Gatorade Sports Drink. Soaking potatoes overnight in Gatorade will increase their electrical conductivity, which will help power your watch. Gatorade contains electrolytes that help electric current pass through the potatoes, but to do so, you will need to soak them in the drink overnight to soak the tubers with electrolytes right down to the center.
   • Gatorade also contains phosphoric acid, which also increases conductivity.
4. 4 Replace potatoes with other conductive fruits. If you still can't power your watch with a potato battery, you can try replacing the potatoes with other conductive fruits. Lemons and oranges are excellent substitutes for potatoes in this experiment. Stick nails and copper plates into them, as you did with potato tubers.
   • To increase the conductivity of the fruit, try rolling it across the table to disrupt the internal partitions, thereby facilitating the movement of internal juices and, as a result, increasing the electric current.
5. 5 Make sure to use the right materials. With the wrong materials, assembling a potato watch battery will be noticeably more difficult, if not impossible. Review your materials and the packaging in which you purchased them to make sure you are using what you need.
   • Make sure to purchase galvanized nails. Despite the fact that in most cases the nails are galvanized, it should be remembered that the experiment with simple nails will fail.
   • Make sure that the electronic watch is powered by a traditional "button cell" battery with a voltage of 1–2 V. You can find out information about the required voltage in the instructions for the watch or on its packaging.

Warnings

• Don't eat used potatoes.
• Young children should supervise this experiment. Nails and wires are sharp enough to cause injury if mishandled. The removal of batteries from the watch should also be done under supervision.