CWU Engineering & Technology

Testing Methods:

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Resources:

• Exercise platform (either a bike in a bike stand or a spinning bike)

• The exercise bike generator

• Temporary charge controller/ volt, amp, watt meter circuit

• 5 Ohm power resistor

• A digital multi-meter capable of measuring the voltage potential of the battery

• A video recording device to record the readout of the Volt, Amp, Watt meter for the duration of the test.

• An assistant to pedal the bicycle or record the video the readout on the Volt, Amp, Watt meter for the duration of the test.

Documentation:

1. The voltage across the battery terminals was recorded with the digital multi-meter both before and after the 5 minute duration of the test. These figures were recorded on the accompanying data sheets.

2. Video record the readout of the Volt, Amp, Watt meter for the duration of the test. After the video is recorded record the volts, amps and watts in the attached datasheets.

3. Additionally the total amp hours that were generated by the generator during the test were recorded at the 5 minute mark.

 

Test Procedure Overview:

            To start this test it was necessary to wire the exercise generator to a different charge controller that only kept the battery from overcharging. This was necessary because the charge controller that was originally specified for this project was made to track the power point of a photovoltaic panned and was not suited to the fluctuating power production of the DC motor. Once that was accomplished the bicycle generator was then attached to a bicycle that had been locked in a bike stand and readied for testing. The voltage on the battery was recorded, the video camera was set up above the volt, amp, and watt meter. The battery was discharged sufficiently for the test by hooking it up to a power resistor, and the test was began. After the conclusion of the test the voltage across the batter terminals was measured again.

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Operational limitations:

The accuracy of the test of this generator are limited by the capacity of the battery. The charge controller in this generator system will prevent the battery from accumulating more than 13.6V so it is necessary to make sure that the battery is significantly discharged so that the battery does not reach 13.6 volts during the duration of the test. To ensure that this condition was met some of the electricity in the battery was discharged through a power resistor.

Another limitation to this test is that, in its current configuration with a borrowed charge controller, the test is challenging to perform with just one person.

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Precision and accuracy discussion:

All of the instruments that were used in this test procedure could ensure up to two decimal points of precision. Since the duration of this test continues for five minutes this amount of precision is more than enough. The accuracy of this test was also somewhat self-confirming in that the battery voltage that is recorded both before and after the test can be cross referenced with the last voltage reading on the video recording of the volt, amp, watt meter.

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Data Analysis:

The battery voltage before and after the operation of this generator is easily measured and transcribed onto the data sheets for this test. The more challenging part of documenting the data on this test occurred in transcribing the data from the video. Although the video quality was sufficient enough to accurately depict the figures that were displayed on the volt, amp, watt meter, those figures would be constantly changing for the duration of the test. This meant that while the figures were changing they were often blurry at the video frame that was nearest to the five second graduation during the test. This blurry image problem was solved by scrolling forward or backward up to .2 seconds in order to find the nearest measurement with a legible image. This method means that any of the data gathered with this method is only accurate to within .2 second of the listed time interval.

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Data Presentation:

The finding for this test are presented in three separate graphs that compare voltage over time, current over time and watts over time. Additionally the total amp hours accumulated during the course of the test will be listed as well as the voltage on the battery before and after the test. The range of motor rpms will be listed on the test sheet as well.

 

Test Procedure: Power production test.

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Summary:

The primary motivation for building this exercise bike generator was to generate power for the charging of small electronics using energy from human effort. A critical test will be to determine how much power a person is generating via the generator. In this initial test the generator will be attached to a standard “spinning bike” and the spinning bike will be operated for five minutes. It is presumed that the generator will meet power production goals within the first 5 minutes of operation and will continue to operate similarly over longer durations.  During this time, volts, amps and watts will be recorded every 5 seconds. The voltage potential of the 5ah battery will be measured both before and after the test to determine the increase in charge of the battery. This test may be performed on platforms other than the spinning bike. For this project this test may be repeated for a variety of different bikes and wheel diameters. It is estimated that a cyclists pedaling in the tour de France can produce from 250-500W.[i] Since the test of this generator will take place over a 5 minute period power output may be higher than 500W and drop as the endurance of whoever is pedaling starts to fade. 

 

Duration:

The duration of this test per pedaling platform will be 5 minutes.

 

Place:

The first test on the spinning bike will occur in Hogue Technology building in either the thermodynamics lab (Hogue 205). In the event that the thermodynamics lab is unavailable the spinning bike will be removed to a vacant location such as the senior project lab.

Additional tests may occur in the thermodynamics lab on the bicycle training stand or in the senior project lab as needed. In order to gain insight on how the generator will interact with the variety of bicycles that it was designed for it will be brought to a local bike shop and the test will be executed with no less than four different bicycle wheel diameters and thicknesses.

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Resources:

The equipment and items required for this test of the exercise bike generator are:

• Exercise platform (either a bike in a bike stand or a spinning bike)

• The exercise bike generator

• Temporary charge controller/ volt, amp, watt meter circuit

• 5 Ohm power resistor

• A digital multi-meter capable of measuring the voltage potential of the battery

• A video recording device to record the readout of the Volt, Amp, Watt meter for the duration of the test.

• An assistant to pedal the bicycle or record the video the readout on the Volt, Amp, Watt meter for the duration of the test.

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Steps for operation and testing:

1. Determine the platform to be used. Either a spinning bike or a bicycle and a training stand.

2. Loosen the cam handle clamps (Part 11, Figure 1) that secure each telescoping leg (Part 4, Figure 1) at the appropriate angle and length so that the large sprocket(Part 26, Figure 1)  is roughly parallel to the interfacing wheel on the exercise platform. An indication good parallelism will be if the exercise platform wheel is centered in the “V” groove on the large sprocket of the generator and touches both sides of the “V” groove.

3. Secure the cam handles so that the telescoping legs are secure.

4. Identify two fixed points on either side of the exercise platform with which to secure the adjustable straps, taking care not to interfere with any drive train components.

5. Loop each strap around the fixed point and secure the strap back on itself using the plastic buckle.

6. Tighten the adjustable straps until the attached springs deflect from their free length approximately 1.5 inches.

7. Set up a camera in position to photograph the volt/amp/watt meter every 5 seconds behind the generator once it is secured. If a multi-meter capable of tabulating electrical data is used it will have to be wired in series between the motor and the charge controller to collect the most accurate generation data.

8. Disconnect the wires from the battery (positive or red wire first) and use a volt meter to measure the voltage potential of the batter before the test begins. Record the initial voltage.

9. Reconnect the wires to the battery starting with the ground, or black wire.

10. With one party monitoring the either the camera or the digital multi-meter and one party operating the exercise platform, start a timer and begin the test.

11. If using a camera to log electrical data, take a picture every 5 seconds until the test concludes.

12. If using a digital multi-meter to tabulate data, start the test on the digital multi-meter and computer and the timer simultaneously.

13. At the conclusion of the test, disconnect the wires from the battery and measure the battery voltage as was done in step 8.

14. Repeat as needed for other exercise bike platforms.

 

[i] http://mapawatt.com/2009/07/19/bicycle-power-how-many-watts-can-you-produce, (4/5/2018)