EGN 100 Introduction to Engineering
Battery Depletion Laboratory
Objectives:
1. To determine how long a nickel metal hydride AAA battery can supply power at a useful level.
2. To determine how the useful time is different for different power levels.
3. To determine how the extracted energy is related to power level.
Procedure:
You have been supplied with one of the following resistances in the form or one or more resistors: 0.5 ohm, 1.0 ohm, and 1.5 ohms. You have also been supplied with an AAA 1.2 volt battery, and a multimeter.
Accept the resistance value written on your resistance apparatus as accurate.
Before you start to collect data, set up a spreadsheet to record the load resistance as a constant in C7, open circuit voltage as a constant in C8, time at 30 second intervals, closed circuit voltage, and calculated current, power, and cumulative energy. Enter the data into the spreadsheet as you collect it.
A / B / C / D / E / F1 / EGN 100 Battery Depletion Laboratory
2 / Date .
3 / Team Members:
4
5 / Current = volts/ohms
6 / Power = volts x amperes
7 / Resistance, ohms / Energy = power x time interval, s
8 / Open-circuit voltage:
9
10 / Time, min / Voltage, V / Current, A / Power, P / Cumulative
Energy, J
11 / 0 / 0
12 / 0.5 / =e11+d11*30
13 / 1.0
14 / Etc.
15
Measure the voltage of the battery before connecting it to the resistor. This is the open-circuit voltage.
At t=0, push the battery into the holder. Measure the voltage immediately (t=0), then at 30 seconds, and at 30 second intervals thereafter. Calculate current, power and cumulative energy. Continue to record data until the battery is nearly depleted, i.e. when the voltage drops to about 0.5 volts.
Plot voltage, current, and power versus time on a single set of axes. We can consider the curve to be continuous, so do not plot data points as there are too many and so close together. Plot cumulative energy versus time on a separate set of axes.
Provide each member of the group an electronic copy of the spreadsheet.
Homework
Each person write a laboratory report following the Laboratory Report Guidelines found in the Laboratories section on the course home page.
When writing the report, imagine you are writing it for someone who is familiar with the subject but who is not familiar with the assignment and has not seen the results.
In the Procedure, describe what you did. Do not write instructions on how to do it. Include a schematic drawing of the circuit. You can also copy the photograph and the schematic diagram of the setup from these laboratory instructions (Laboratory 2 on the web page) and paste them into your report. See also the document having the link “Incorporating photos and tables in a lab report.”
Place your charts at appropriate places in the Results section, near where you describe them. How do the magnitudes of voltage, current and power change with time? If you want to have a reasonably constant power, after how many minutes does the power drop to a level so as to be no longer useful? What is the power at that time? What is the average power level for the entire useful power period? What happens to the cumulative energy curve as the battery becomes depleted? What is the useful energy extracted from the battery?
You will be provided with the useful power level, time of useful power, and energy extracted for a collection of experimental results. Place this chart in the Results section. Describe how the duration of useful power is related to the power level. Describe how the energy extracted is related to the power level.
Don’t forget to discuss the results, provide an interpretation of what they mean, comment on ways the experiment might be incomplete, how it might be improved, how the results can be used in the HexA challenge, etc.
Put your original spreadsheet columns of data in an Appendix. Do not put them in the body of the report.
Do your best. I will critique your report with an aim to improving it.
Submit the report as a file named XBatteryDepletion.doc to your portfolio in the Laboratories folder, where X is your last name. Create a link to it on your home page.