What if the alternator was only putting out 12.8 volts because the battery was close to fully charged? The next experiment is to use a battery that is almost fully discharged and see if the alternator output increases.
Friday 8/29/14 - Today I purchased fishing weights and attached them to 2 out of 3 spokes on the rear wheel of the bicycle. We hoped this would create a sort of flywheel effect and make the pedaling easier to sustain. A close-up of the weights is shown in a picture below the video. We packed up the bicycle generator and took it to an empty lot - the site of an outdoor concert. We hoped to test a larger sound system with the battery. My husband, Matt, tried pedaling the bicycle generator. As you can see in the video, around the 30 second mark, when the switch is flipped to the "on" position to give current to the alternator, the resistance increases significantly and the bicycle becomes very difficult to pedal. Around the 38 second mark, Matt shifted to a lower gear. This made the pedaling a little easier. Still, the voltage output by the alternator was about 12.8-12.9 volts. Matt was able to get 13.00 volts with a short burst of intense pedaling, but it was not sustainable for more than a few seconds. Thus, we are about 2 volts short of being able to charge the battery. I am not sure what to try next - We can now generate voltage from the alternator; however the bicycle is extremely difficult to pedal (even in a low gear) when the battery is being charged. Thus, the highest voltage we have been able to generate is 12.88 volts. So now the question is: what modifications can be made that will increase the RPM's and/or increase "pedalability"? One suggestion was to add weight to the rear wheel of the bicycle to create a flywheel effect. We have made progress on the stand, but are stuck at the wiring phase. We are learning a lot about how alternators work and how other people have used them for bicycle generators, but still have some obstacles. Hopefully we can overcome those in the next few days so that we can try to charge the battery during a 1-hour outdoor concert on Friday. Today my husband and I built the stand for the bicycle that will be connected to an alternator. We spent time watching YouTube videos on different alternator scenarios. Tomorrow we hope to obtain an alternator, a switch, and a belt. How much does the amplifier volume affect the amount of power required? Does the volume needed for an outdoor concert, such as the one on October 19, draw significantly more power? These questions will be answered through the use of a kill a watt meter. This tool measures the amount of watts used by a device. I will measure the watts used by the sound system at different volume settings.
I borrowed a 100 amp hour battery and inverter from Interstate Battery so I could test out the sound system to see how long the battery would last. For the off-the-grid concert, I will need 5-6 hours of power. This first test went well. Since I was using the sound system in my house, I did not turn up the volume as loud as will be necessary for the concert. However, I am optimistic that a solar panel or bicycle generator will be able to charge the battery sufficiently to maintain power for the enire length of the concert. During the battery test, I measured and recorded the voltage of the battery every 30 minutes.
Start: 12.83 v 30 min: 12.73 v 1 hour: 12.72 v 1.5 hour: 12.71 v 2 hours: 12.70 v 2.5 hours: 12.69 v 3 hours: 12.67 v 3.5 hours: 12.65 v 4 hours: 12.63 v 4.5 hours: 12.62 v 5 hours: 12.60 v 5.5 hours: 12.58 v 6 hours: 12.56 v The battery would be considered to be 75% charged at 12.65 volts and 50% charged at 12.45 volts. Thus, after 6 hours, the battery was still over 50% charged. For two reasons we are going to power our sound system with a battery. The first reason is the reliability and consistency of a battery. Since one of our goals of the event is to provide high quality entertainment, we want to make sure that the power will not immediately fail even if one of the alternative energy generating sources fails. Also, I feel that by experimenting with a battery, I am modeling how one might use alternative energy in a home. A person may want to use electricity when it is not sunny or windy, or when they are not pedaling a bicycle generator. Therefore, energy storage is an issue. I want to demonstrate that net metering is a way to use the power grid for storage, while disconnecting from the power grid will require a battery for energy storage.
The purposes of this event are to entertain and to educate. We intend to raise awareness about alternative energy sources and to educate people about ways in which they are impacting the environment and how they can reduce that impact.
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