DIY Power: Battery Modules for Emergencies

Materials and Preparation:

• 4 – Zinc Strips per student
• 4 – Copper Strips per student
• 4 – Aluminum Strips per student
• 2 lemon cut in half or 4 whole per student
• 2 potato cut in half or 4 whole per student
• ½ cup of vinegar and saltwater per student
• 4 – Alligator Clips w/ Electrical Wires per student
• 2 – each color LED light bulbs per student
• 1 – Multimeter per group of 2 students
• Data Collection Chart
• Student worksheets

Testing Materials & Process:

• Digital Multimeter
• Alligator Clips w/ Electrical Wires
• Battery Modules
• LED light

Process: Teams will use a multimeter to conduct a load test on their simple cell battery. They will connect the battery module to the LED light (a known resistive load) and measure the voltage drop when the light is on. A healthy battery should maintain a stable voltage under load. If the voltage drops significantly, the battery module may be weak or defective.

Teacher Preparation Tips:

• Review Background Concepts
• Review Teacher Tips in the Activity Instructions and Procedures Section
• Gather, Prepare, and Sort Materials
• Create Small Groups and Distribute Materials
• Demonstrate each activity for students prior to allowing students to complete the activity

Teacher Tip: Each electrolyte variable in this experiment represents a single battery cell. By testing different variables, students can explore a broader range of outcomes and optimize their battery cell design for various scenarios. Specifically, by using different metals and adjusting the distance between them with additional alligator clips, students can experiment with connecting multiple cells into a battery module to generate a higher voltage and stronger battery.

• Battery Module: A group of battery cells connected together to provide more power.
• Battery Pack: A larger unit made up of multiple battery modules.
• Series Connection: Connecting battery cells end-to-end to increase the voltage.
• Parallel Connection: Connecting battery cells side-by-side to increase the capacity.

Title: Emergency Battery Cell for LED Lighting

Scenario: Severe weather has left several counties in your state without power. Your team of electrical engineers is challenged with designing a reliable and efficient emergency battery cell system that produces a measurable electrical current sufficient for LED lighting. Therefore, the team needs to understand how batteries generate electrical flow.

Research and Brainstorm: Instruct students to research the problem. Then, have them brainstorm possible solutions and explore potential real-world applications for emergency power solutions.

Design Criteria: The Battery cell system should produce a measurable electrical current sufficient to power LED lights. It must be designed using readily available materials and should be efficient, cost-effective, and safe.

Design: Have students create a detailed design plan/diagram of a reliable and efficient battery cell system that can serve as the power source for LED lighting.

Build Prototype: Instruct students to build a prototype of their design to test and confirm its functionality.

Test: Ask students to evaluate their initial design by measuring the voltage and current generated by the battery cell. They should document the voltage and current readings in the data collection chart. Then check if the LED lights up, noting any problems and suggesting improvements. Data Collection Chart

Iteration and Refinement: Next, instruct them to experiment with different combinations of the listed variables to find the most efficient, cost-effective, and safe configuration. They should measure and document the voltage and current generated by each battery cell comparing the performance of various battery cell configurations. They should then identify which variables had the most significant impact on the battery cell’s ability to power the LED, noting any issues and proposing improvements. Based on the feedback from iterative testing, they should refine the design to enhance its performance and resolve any identified problems.

Variables:
1. Type of Electrolyte:

• Lemon
• Saltwater
• Vinegar
• Potato

2. Temperature of the Electrolyte:

• Room Temperature
• Heated
• Cooled

3. Type of Metals Used:

• Copper and zinc
• Copper and aluminum
• Zinc and aluminum

4. Distance Between Metal:

• Close proximity
• Medium distance
• Far distance

5. Color of LED Light

• Different Colors (which may have different voltage requirements)
  

Presentation: Summarize the findings from the testing and iteration phases. Develop a presentation that highlights the most effective battery cell configuration and explores potential real-world applications for emergency power solutions.

Step 1 | Introduce Scenario
*Teacher Tip: Present the following scenario to the students.
Severe weather has left several counties in your state without power. Your team of electrical engineers is challenged with designing a reliable and efficient emergency battery cell system that produces a measurable electrical current sufficient for LED lighting. Therefore, the team needs to understand how batteries generate electrical flow.

Step 2 | Research

Step 3 | Create a Simple Battery Cell

DEMO: The steps below and monitor students as they complete each task.

To create a simple battery cell, follow these instructions:

1. Prepare the Lemon: Roll the lemon on a table so the juices flow easily.
   
   Make 2 incisions in the lemon.
   
2. Prepare the Electrodes: Insert the copper strip into one side of the lemon.
   Insert the zinc strip into the opposite side of the lemon, making sure the two items do not touch each other.
   
3. Connect the wires: Attach one end of a wire with an alligator clip to the copper strip.
   
   Attach one end of a wire with an alligator clip to the zinc strip.
   
4. Test if current, is flowing using the Multimeter:
   • Turn on the multimeter.
   • Set it to measure DC voltage (usually indicated by a “V” with a straight line and dashed line beneath it).
     
5. Connect the Probes:
   • Insert the black probe into the common (COM) port.
   • Insert the red probe into the port labeled for measuring voltage (often marked as “VΩmA” or similar).
     
     
6. Measure the Voltage of the Lemon Battery:
   • Touch the black probe to the zinc strip (negative electrode) and the red probe to the copper strip (positive electrode).
   • Read the voltage displayed on the multimeter and record it in the provided data collection chart.*It should show a small voltage, typically between 0.5 to 1.5 volts, depending on the electrolyte and the condition of the electrodes.
     

Optional Kahoot: Lemon Battery Science Quiz

Step 1 | Explore Key Concepts
*Teacher Tip: Before starting the hands-on activities, introduce these key concepts to students.

NOTE: When a copper and zinc strip is inserted into a lemon, a simple battery cell is created through a chemical reaction known as an electrochemical reaction. This process generates a small voltage, enough to power a small device like an LED light!

1. Electrodes: The copper and zinc strips act as electrodes. Copper is the positive electrode (cathode), and zinc is the negative electrode (anode).
2. Electrolyte: The lemon, potato, saltwater or vinegar serves as the electrolyte. These substances contain acids or salts that facilitate the flow of ions.
3. Oxidation at the Anode: At the zinc electrode (anode), zinc atoms lose electrons (oxidation) and become zinc ions (Zn→Zn2++2e−). These electrons are released into the external circuit.
4. Reduction at the Cathode: At the copper electrode (cathode), hydrogen ions (H+) from the electrolyte gain electrons (reduction) to form hydrogen gas (2H++2e−→H2).
5. Electron Flow: The electrons flow from the zinc strip through the external circuit to the copper strip, creating an electric current.
6. Ion Movement: The zinc ions (Zn2+) move into the electrolyte, while hydrogen ions (H+) in the electrolyte move towards the copper electrode to balance the charge.

Step 5 | Creating a Battery Module
*Teacher Tip: If steps 1-5 are completed on the same day, skip to step 3 below.

DEMO: The steps below and monitor students as they complete each task.

To create a battery module, follow these instructions:

1. Prepare the Lemon: Roll the lemon on a table so the juices flow easily.
   
   Make 2 incisions in the lemon.
   
2. Prepare the Electrodes: Insert the copper strip into one side of the lemon.
   
   Insert the zinc strip into the opposite side of the lemon, making sure the two items do not touch each other.
3. Connect the wires: Attach one end of a wire with an alligator clip to the copper strip.
   
4. Connect the Lemons in Series:
   • Using the alligator clip wires to connect the lemons in series.
   • Connect the copper strip of the first lemon to the zinc strip of the second lemon.
     
   • Continue this pattern: Connect the copper strip of the second lemon to the zinc strip of the third lemon, and so on. *You should have one zinc strip and one copper strip free at the ends of the series connection.
     
5.  Test if current, is flowing using the Multimeter:
   • Turn on the multimeter.
   • Set it to measure DC voltage (usually indicated by a “V” with a straight line and dashed line beneath it).
     
6. Connect the Probes:
   • Insert the black probe into the common (COM) port.
   • Insert the red probe into the port labeled for measuring voltage (often marked as “VΩmA” or similar)
     
     
7. Measure the Voltage of the Battery Module:
   • Touch the black probe to the zinc strip (negative electrode).
   • Touch the red probe to the copper strip (positive electrode).
   • Read the voltage displayed on the multimeter and record it in the provided data collection chart.

Step 6 | Add an LED light to the circuit
DEMO: The steps below and monitor students as they complete each task.

To add an LED bulb to the circuit, follow these instructions:

Connect the free ends of the wires to the terminals of the LED bulb. The LED should light up if the circuit is complete.

*If the LED does not light up, try reversing its wires (LEDs have positive and negative terminals of their own that need to match to the same polarity of the battery).

Explanation:
How it works: The lemon juice acts as an electrolyte, allowing the flow of ions between the copper and zinc strips. This electrochemical reaction creates a flow of electrons, generating electricity.

Series Connection: By connecting the lemons in series, you add up the voltage of each lemon cell, making the battery module powerful enough to light up the LED or run the clock.

Step 4 | Explore Key Concepts
*Teacher Tip: Before starting the hands-on activities, introduce these key concepts to students.

NOTE: Now that students have successfully built a simple cell battery, we will take the next step in our exploration by constructing an advanced battery module. This battery module will be designed to generate a measurable electrical current capable of powering an LED light. Through this process, students will gain a deeper understanding of how multiple lemons (cells) can be connected to enhance voltage and current output. Additionally, you will discuss key concepts such as series and parallel configurations, energy storage and real-world applications of battery technology in sustainable energy solutions.

What is a Battery Module?
A battery module is like a team of small batteries working together to provide power. Imagine you have a bunch of small batteries, like the ones you use in toys or remote controls. When you connect these small batteries in a certain way, they can work together to create a bigger, more powerful battery. This bigger battery is called a battery module.

How Does It Work?

1. Battery Cells: Think of each small battery as a cell. A battery module is made up of many of these cells.
2. Connections: The cells can be connected in two main ways:
a. Series Connection: This adds up the voltage of each cell. For example, if you connect two 1.5V cells in series, you get 3V.
b. Parallel Connection: This adds up the capacity (how long the battery lasts) of each cell. For example, if you connect two cells with 1,000mAh each in parallel, you get 2,000mAh.
3. Protective Case: All the cells are put together in a protective case to keep them safe and organized.

Why is it Important?
Battery modules are used in many things you see every day:

• Electric Vehicles: Battery modules help power electric cars, buses, and bikes.
• Renewable Energy Storage: They store energy from solar panels and wind turbines so we can use it later.
• Portable Electronics: Devices like laptops, smartphones, and power tools use battery modules to run.
• Backup Power Systems: Battery modules provide power during outages, like in uninterruptible power supplies (UPS).

Fun Fact:
Just like how a team works better together, battery cells in a module work together to provide more power and last longer than a single cell on its own!

What is an Electric Vehicle?
An electric vehicle (EV) is a type of vehicle that runs on electricity instead of gasoline or diesel. It uses a battery to store electrical energy, which powers an electric motor to move the vehicle. The battery is a crucial component, providing the energy needed to drive the car. Over time, the battery’s capacity can degrade, reducing the vehicle’s range. Due to safety and performance concerns of the high power demanded by EVs these batteries are retired from use in EVs when their capacity reaches 70%-80% of the original capacity. Improperly discarding batteries can harm the environment, as they contain chemicals that can leach into the soil and water, causing pollution. To address this, second-life EV battery technology repurposes used batteries for other less power demanding applications, such as energy storage for homes and businesses or even charging stations, extending their useful life and reducing waste. The electric motor receives the electrical energy from the battery and converts it into mechanical energy to turn the wheels, operating efficiently and producing no emissions. The charging port is where you plug in the vehicle to recharge the battery, connecting to an external power source like a home charger or public charging station. Together, these components enable electric vehicles to operate cleanly and efficiently, making them an eco-friendly alternative to conventional vehicles.

How do electric vehicles differ from gas-powered cars?
Electric vehicles (EVs) and gas-powered cars have some key differences. EVs run on electricity stored in batteries, while gas-powered cars use gasoline or diesel fuel and rely on an internal combustion engine to transform thermal to mechanical energy.1 This means that EVs don’t have a traditional engine; instead, they have an electric motor that is quieter and more efficient. EVs produce no tailpipe emissions, making them better for the environment, whereas gas-powered cars directly release pollutants and greenhouse gases that contribute to air pollution and climate change. Charging an EV involves plugging it into a charging station, similar to how you charge a phone, while gas-powered cars need to be refueled at gas stations. Additionally, EVs often have fewer moving parts, which can lead to lower maintenance costs compared to gas-powered cars. These differences make EVs a cleaner and often more cost-effective option for transportation. Gas-powered cars also have batteries, but these are not a direct source of energy for movement.

Common Barriers to Owning Electric Vehicles
Owning an electric vehicle (EV) can be challenging for several reasons. First, electric cars can be more expensive to buy than regular gas cars, making them less affordable for many people. Additionally, there aren’t as many charging stations as there are gas stations, which can make it difficult to find a place to recharge, especially on long trips. Charging an electric car also takes longer than filling up a gas tank, which can be inconvenient. Electric cars usually can’t travel as far on a single charge as gas cars can on a full tank, which can be a problem for long-distance driving. Over time, the battery in an electric car can wear out and hold less charge, reducing the car’s range. There are also fewer models of electric cars to choose from compared to gas cars, so people might not find one that fits their needs. Lastly, some people don’t know much about electric cars or have misconceptions about them, which can make them hesitant to buy one. Understanding these barriers can help us find ways to make electric cars more accessible and popular!

Battery Basics
Battery energy sources. For example, logs and oxygen both store energy in their chemical bonds until burning converts some of that chemical energy to heat… Similarly, for batteries to work, electricity must be converted into a chemical potential form before it can be readily stored. Batteries consist of two electrical terminals called the cathode and the anode, separated by a chemical material called an electrolyte. To accept and release energy, a battery is coupled to an external circuit. Electrons move through the circuit, while simultaneously ions (atoms or molecules with an electric charge) move through the electrolyte. “In a rechargeable battery, electrons and ions can move either direction through the circuit and electrolyte. When the electrons move from the cathode to the anode, they increase the chemical potential energy, thus charging the battery; when they move the other direction, they convert this chemical potential energy to electricity in the circuit and discharge the battery. During charging or discharging, the oppositely charged ions move inside the battery through the electrolyte to balance the charge of the electrons moving through the external circuit and produce a sustainable, rechargeable system. Once charged, the battery can be disconnected from the circuit to store the chemical potential energy for later use as electricity.”

Combining Battery Cells to Create Battery Modules
A single battery cell is often not enough to power model electronics. For example, our TV remotes usually require 2-3 single-cell batteries. Car batteries need to store and release a lot of energy. To provide for this demand, battery cells are connected together into battery modules to provide more power. Even a battery module may not provide the power needed for a device, so battery modules can be combined into a Battery Pack.

Batteries can be connected in two ways, series and parallel. Series and parallel connections are fundamental for designing and comprehending electrical circuits across various applications. Each connection type influences the performance and efficiency of electrical systems. Grasping these differences is vital for optimizing electrical systems, from basic household electronics to intricate industrial machinery. By mastering series and parallel connections, engineers and technicians can create circuits that meet specific voltage and capacity needs, ensuring optimal functionality and reliability. A series connection is where batteries are connected end-to-end to increase the voltage. Voltage is a measure of electrical potential difference between two points in the battery and reflects how much “push” a battery can generate. Battery cells can also be in parallel connections where the cells are side-by-side. This increased the capacity of the battery. Capacity is the amount of energy a battery cell can store, usually measured in milliamp-hours (mAh).

Battery Safety
Anytime a battery is used, there are safety considerations. Combining cells into modules and packs can increase these risks further. Lithium-ion batteries have their own special considerations. Engineers are working on Battery Management Systems (BMS): that monitor and manage the performance of the battery pack and can help detect issues before they become dangerous. One potential issue is heat when many batteries are combined together. Thermal Management is the process of controlling the temperature of the battery pack to ensure safe operation. Battery safety systems include protections to prevent overheating, overcharging, and short circuits in battery modules.

Electric Vehicle/Car:

• Electric Vehicle/Car: A vehicle/car that runs on electricity instead of gasoline.
• Battery: An electrochemical device that stores energy and can be used to power electrical devices and equipment such as electric cars.
• Charging Station: A place where you can plug in your electric car to recharge its battery.
• Range: The distance an electric car can travel on a full battery charge (e.g. 200 miles).
• Regenerative Braking: A system that captures energy when the car slows down and uses it to recharge the battery.
• Hybrid Car: A car that uses both an electric motor and a gasoline engine.
• Plug-in Hybrid: A hybrid car that can be recharged by plugging it into an electrical outlet.
• Kilowatt-hour (kWh): A unit of energy that measures how much electric energy is used.
• Zero Emissions: Producing no harmful gases or pollutants.
• Eco-friendly: Good for the environment.

Simple Battery Cells

• Voltage: The measure of electrical potential difference between the two terminals of the battery (electric force). It is defined as the energy per one Coulomb (C) of charges. It is measured in unit of Volt (V). For example, 5 V indicates 5 Jouls (J) of energy per one Coulomb (C).
• Current: The speed at which the charges flow in or out of the battery. It is measured in unit of Ampere (A). For example, 5 A indicates 1 Coulomb (C) of charges flows every one second. Every 1 C is approximately equivalent to 6.25 x 10^18 electrons.
• Battery Cell: The basic unit of a battery that stores and releases electrical energy.
• Electrode: A conductor through which electricity enters or leaves the battery cell.
• Anode: The negative electrode where electrons flow out of the battery during discharging and into the battery when charging. Note that the direction of the electric current is opposite to the direction of electrons.
• Cathode: The positive electrode where electrons flow into the battery during discharging and out of the battery during charging.
• Electrolyte: A liquid or gel that conducts electricity inside the battery cell.
• Capacity: The amount of energy a battery cell can store, usually measured in amp-hours (Ah). • Discharge: The process of using the stored energy in the battery cell.
• Recharge: The process of restoring energy to the battery cell.

Battery Modules

• Battery Module: A group of battery cells connected together to provide more power, energy, and higher voltage (in series connection) and/or current (in parallel connection).
• Series Connection: Connecting/staking battery cells end-to-end (positive with negative) to increase the voltage (which will also increase capacity).
• Parallel Connection: Connecting battery cells side-by-side (positive to positive and negative to negative) to increase the current capability (which will also increase capacity).
• Battery Pack: A larger battery unit made up of multiple battery modules.
• BMS (Battery Management System): A system that monitors and manages the performance of the battery pack to ensure longer life and safer operation.
• Thermal Management: The process of controlling the temperature of the battery pack to ensure safe operation.
• Cycle Life: The number of charge and discharge cycles a battery can go through before its capacity reaches a value when it cannot or should not be used anymore in a given application.
• Energy Density: The amount of energy stored in a battery relative to its size or weight.
• Lithium-ion Battery: A type of rechargeable battery commonly used in electronics and electric vehicles.
• Safety Features: Built-in protections to prevent conditions that can cause failure or performance degradation such as overheating, overcharging, and short circuits in battery modules.

History
One of the earliest scientists working on electric batteries was Alessandro Volta around 1800 (note that his name gave us the term “voltage” and measurement units of “volt”). By the mid-1800s, scientists developed early rechargeable batteries.

https://batteryuniversity.com/article/bu-101-when-was-the-battery-invented
https://nationalmaglab.org/magnet-academy/history-of-electricity-magnetism/museum/plante-battery-1859/

Resources
How batteries work – Adam Jacobson (TED-Ed) 
https://www.acs.org/content/dam/acsorg/education/outreach/kidszone/kids-zone-build-a-lemon-battery.pdf
https://www.energy.gov/science/doe-explainsbatteries
https://www.energy.gov/eere/water/electrical-engineer-0

Energy Storage
https://tryengineering.org/news/energy-storage-tryengineering-tuesday/

Global functional alignment