H2 Fuel Cell Car

From a child's room to a small laboratory

How does a fuel cell work? How can you use it to generate hydrogen? The H2 Fuel Cell Car teaches students about this exciting topic. They can use the fuel cell and vehicle to investigate the properties of hydrogen. They can also build interesting additional models in conjunction with the Green Energy building set.

Please note the safety instructions at the end!

Functional principle behind the fuel cell

Fuel cells are used to convert the chemical energy in a fuel (such as hydrogen) into electrical current. A fuel cell, therefore, is not used to store energy, but rather to convert it.
Fuel cells are used, for instance, to drive vehicles and to heat and supply power to homes.
A fuel cell consists of two electrodes (anode and cathode), which are separated from one another by an electrolyte membrane.
The electrodes are generally made of metal or carbon. They are coated with a catalyst, such as platinum or palladium.
Hydrogen and oxygen react in the fuel cell to produce water. This reaction creates electrical voltage between the two electrodes, which can be used to drive an electric motor, for example.

Types of fuel cells

The fuel cell in the H2 Fuel Cell Car is what is called a reversible fuel cell. That means that the fuel cell has the following two functions:
- First, the reversible fuel cell can be used as a so-called electrolyzer, to produce hydrogen and oxygen from distilled water. This process is called electrolysis. The hydrogen and oxygen are stored in storage cylinders.
- Second, the reversible fuel cell can generate electrical energy from the reaction between the stored hydrogen and stored oxygen.

Operating the fuel cell

Description of the fuel cell:
1. Overflow chamber, hydrogen side 
2. Hydrogen storage cylinder 
3. Plugs for the vent ducts 
4. Oxygen storage cylinder
5. Negative connector (black)
6. Protective diode
7. Positive connector (red)
8. Overflow chamber, oxygen side
9. Fill level marking

Filling the fuel cell with distilled water

To do so, place the fuel cell on a flat plate.
Then remove the two plugs (3) from the vent ducts. Fill the two storage cylinders to the fill level marking (9) with distilled water. (See Fig. A)

Caution, possible material damage: Tap water or other liquids will cause permanent damage to the fuel cell membrane.
The air in the fuel cell will escape when water is added through the vent ducts. Knock the fuel cell lightly against the table to help the water flow better around the membrane and the current collector metal plates. 
Add a little more water, just until water escapes from the vent ducts, and the water in the overflow chambers reaches up to the fill level marking. 
Now, you can use the plugs to seal off the vent ducts once again. Ensure that no air is trapped in the storage cylinders. A small air bubble will not cause any problems, and can be ignored. 
If the fuel cell has not been in use for a long period of time, wait for around 10 minutes to ensure the membrane is sufficiently saturated.

Generating oxygen and hydrogen (electrolysis)

The fuel cell must be supplied with a direct current of between 1.8 and 3 volt. 
Caution, possible material damage: If the voltage is too high, the fuel cell membrane may be destroyed. The fuel cell may never be connected to a 9V fischertechnik power supply.

Connect the enclosed 3V power supply as shown in the wiring diagram to the fuel cell, which is already filled with distilled water, and plug the 3V power supply into the outlet. 
Once enough current is flowing, the production of hydrogen and oxygen will begin. The gases will be stored in their respective storage cylinders. The water will be pressed into the overflow chambers above.
The fuel cell is fully “charged” once all water has been pressed out of the hydrogen storage cylinder (2) into the overflow chamber above (1). This process will take around 2 – 3 minutes.
Now, you can unplug the fuel cell from the charging cable. This will stop the production of hydrogen and oxygen. 
Tip: To ensure optimal performance for your fuel cell, flush all air out of the fuel cell. To do so, continue generating hydrogen until all water has been pressed out of the oxygen storage cylinder and into the overflow chamber above.

Experiment 1:

Start generating hydrogen. Observe the amount of water pressed by the hydrogen and oxygen into the two overflow chambers. What do you observe?

Answer:

Twice as much hydrogen is produced as oxygen. 

Why is that?

Water (H2O) consists of compounds of hydrogen (H2) and oxygen (O2). These compounds are called water molecules. A water molecule consists of two hydrogen atoms and one oxygen atom. When the molecule is split during electrolysis, this produces twice as many hydrogen molecules as oxygen molecules.

Generating electrical energy

Once there is hydrogen and oxygen in the storage cylinders, they will react with one another and generate electrical voltage on the connectors between 0.5 and 0.9 V. The fuel cell delivers a current of 600 mA, and has a rated output of 300 mW.

Experiment 2:

Connect the included motor to the fuel cell connectors.

What do you observe?

The motor begins to turn. It is being driven by the electrical energy generated by the fuel cell.

Fuel cell vehicle

Fuel cell vehicles are means of transportation using electric motors, for which the required electrical energy is generated using a fuel cell from hydrogen or methanol. Research on this type of drive has been increasing greatly in the last few decades. Fuel cell vehicles are beginning to compete with battery-operated electric motors.
Due to problems with battery range and economic efficiency (price and service life), some automotive manufacturers currently favour fuel cells as the best technology for the future. However, as yet little infrastructure has been constructed for hydrogen production, storage, or for refilling vehicles.

Experiment 3:

Now, build the complete fuel cell vehicle. Allow the vehicle to drive straight ahead, and measure how long the vehicle can drive, or what distance it can drive with the fuel cells filled.

Repeat this experiment after adding a curve, and on different surfaces (rough, smooth, etc.). What do you observe?

Answer:

The less friction is present, the faster and farther the vehicle can drive on a single “tank”. 

Combination models H2 Fuel Cell Car and Green Energy

If you have the H2 Fuel Cell Car and the Green Energy building set as well, you can also try the following tasks:

Task 1:

Build the wind power plant with fuel cell for the following experiments, as described in the building instructions.
The fuel cell is installed parallel to the solar modules. This is charged at the same time as the wind power plant operates.

Experiment 1:

- Fill the fuel cell with distilled water and place the model in the sunshine, or illuminate the solar module with a suitable light source (such as a 100 W incandescent bulb at a distance of 30 m).

What do you observe?
The wind power plant moves, while hydrogen and oxygen are generated in the fuel cell at the same time. The motor and fuel cell are connected in parallel.

Experiment 2:

- Now, wait until a certain quantity of hydrogen has been generated, then cover the solar module or switch off the light source.

What do you observe now? Also watch the hydrogen storage cylinder.

The model will run more slowly, but it will not stop. The fuel cell is using hydrogen.
When the light intensity is reduced, the model is operated by the fuel cell. This will ensure the wind power plant can operate even after the sun goes down, or if the sun is covered by a cloud.
The reason the model is running more slowly is that the fuel cell delivers a lower voltage than the solar module. An electric motor turns more slowly when it is supplied with lower voltage.

Task 2:

Build the wind power plant with fuel cell, or the sky dancer with fuel cell. 

Experiment 1:

- Do not hold down the built-in button.

What do you observe?
The fuel cell is supplied with current by the solar module. Hydrogen and oxygen are being produced.

Experiment 2:

 - Now hold down the built-in button.

What do you observe now?
The motor is supplied with current by the fuel cell and begins to turn. This means that the oxygen and hydrogen produced are being used to produce current in the fuel cell.

Troubleshooting

Fault

Possible cause

Fault correction

Unusually high voltage when a load is connected to the fuel cell

Layer on the surface of the catalyst

The layer on the surface of the catalyst that increases the initial output voltage of the fuel cell will disappear after just a few seconds

No or very slow hydrogen production

Incorrect connection between the power supply and fuel cell

Check the connections and

correct as needed

Fuel cell membrane is too dry

Allow the fuel cell to stand for 30 minutes filled with distilled water

Low fuel cell performance

Fuel cell membrane is too wet

Pour water out of the fuel cell and allow the fuel cell to stand open for a day

Model (motor) does not move or only moves slowly

Components do not move smoothly.



Components not installed in accordance with the building instructions.

Check to make sure the movable components can move easily.

Compare the model setup with the building instructions.

 

Vehicle does not move, or drives backwards.

Motor not connected, or connected incorrectly to the fuel cell

Check the motor connection, see the wiring diagram.

 

Decommissioning / storing the fuel cell

The fuel cell should not be stored filled with water. 
Therefore, after each experiment remove the plugs from the fuel cell and pour out the water. Shake the fuel cell to ensure it is completely empty. Then allow it to dry thoroughly. 

Instructions for environmental protection

The electrical and electronic components in this building set (such as motors, lights, sensors) should not be placed with household rubbish. They must be delivered to a collection point for recycling electrical and electronic devices at the end of their service life. The symbol on the product, the packaging or the instructions indicates this.

Liability

fischertechnik GmbH shall accept no liability for damages resulting from the building set being used in a manner other than its intended use.

Fuel cell technical data
 

General information

 

Operation as an electrolyzer

 

Operation as a fuel cell

 

Operating temperature

10 – 40 °C

Operating voltage

2 – 3 V

Operating voltage

0.5 – 0.9 V

Storage temperature

5 – 40 °C

Operating current

400 – 1500 mA

Operating current

600 mA

Hydrogen storage capacity

20 ml

Maximum hydrogen production rate

8 ml / min

Rated power

300 mW


Important safety instructions in advance

WARNING!

For use by children over the age of 10 only. To be used only under the close supervision of adults, who have taken the necessary precautions described in the experiments kit. Read the instructions before use, follow them and keep them ready to hand.
They contain instructions for parents and these must be followed. Keep the packaging and instructions, as they contain important information. Hydrogen is produced during the experiment. Hydrogen can form an explosive mixture with atmospheric oxygen. Therefore, all ignition sources must be removed before carrying out the experiment.

Advice for supervising adults

  • This experiments kit is only intended for use by children over the age of 10 years.
  • The instructions should enable adults to assess the experiment's suitability for the child concerned.

Safety rules

  • Read these instructions before starting the experiment, follow them and keep them ready to hand.
  • Keep the experiments kit out of reach of small children.
  • Do not put wires into the electrical outlet.
  • Warning: Do not remove the protective diode between the connections of the fuel cell! It prevents irreparable damage to the fuel cell if a short circuit occurs between the positive pole (red) and the negative pole (black) or if cables get too hot.
  • Do not short circuit the fuel cell (explosion hazard)!
  • Warning: (Connection) errors or unauthorized changes can cause temperature increases on exposed surfaces that can exceed the allowable limits!
  • The fuel cell may only be operated with a direct voltage up to 3V. Never connect any other power supplies, e.g. 9 V fi schertechnik.
  • Do not short circuit the contact points of the fuel cell.
  • Too high voltage or a short circuit can destroy the fuel cell membrane.
  • Do not produce electricity or hydrogen for any purposes other than those given in the instruction manual.
  • Do not produce or store more hydrogen than fi ts in the storage cylinder of the fuel cell (around 20 ml).
  • Avoid continuous charging of the fuel cell.

Proper use

The Fuel Cell kit's fuel cell may only be used to operate fischertechnik models.

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