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The Trip
Our trip was scheduled to be from Friday, August 7 to Tuesday, August 11. On Friday, though, we wanted to add lights to the front and back to make it safer. This meant rewiring the battery going to the controller so that power went both to the lights and the controller. We finished the bike that night and went to test ride it. When we went up a big hill, the power shut off. I smelled burnt wires and found that the Anderson Connectors in the controller melted and the power shut off. Even though the controller should have been able to handle 2000 W and we did not use that much power, we decided that the issue must have been that the controller was overtaxed. We had an extra controller, so we rewired that into the bike with better connections and used end caps to connect the wires instead of Anderson Connectors. The next day we set off for our first day of biking. Because summer was ending and my brother's birthday was in five days, we were running out of time to go on our trip. On Saturday, even though it would have been better to do more test runs with the bike, we rode off for our first day. After some time riding, we got to another hill where the wires once again melted (pictured left).
We called the distributor of the motor, Rafe Husain from Calibike.com. He said he would give us new controllers. These two were beefier and stronger. Rafe put new wires with better connections on the controller and commented that some of our connections were not ideal. He is an electrical engineer at a major company but distributes motors as a hobby. Rafe was super helpful and open to consulting with us about the project.
I found online that overheating can be caused by too much power or bad connections. We went home and soldered the wires that go from the solar panels to the MPPT, from the MPPt to the battery, and from the battery to the controller. This is done by melting metal between the connections to make them more solid and conducive.
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The bike wouldn't work. We thought that we soldered wrong so we cut out all the connections and put on new connections.
It still didn’t work. The next morning, we realized we didn't turn the key in the battery, so we did that and it was successful. This was frustrating because it was a simple mistake that led to hours of extra work.
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We drove out a little past where we broke down the day before into Santa Monica and took off. We went a little way, but once again it suddenly stopped working. We figured it was the controller, but the controller wasn’t hot, and nothing had burnt through. In retrospect, I think that it was because the motor and the battery we used that day - a 48 V rather than the 52 V we had used the day before - required different voltages. The distributor had said it didn’t matter that they were different. The next day we used the 52 V battery and it worked.
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The reason we had switched from the 52 V battery to the 48 V battery before was because the mppt was programmed to control power going into a 48 V battery and it was not charging the battery with the dc power from the solar panels until the charge in the battery dropped significantly.
To solve these two problems - the mppt and the controller - next time we plan to use a pmw (as explained in the mppt section) and a more powerful, heavy-duty controller.
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On the final day we took off around where we stopped the day before and biked all the way up to Big Sur. In Big Sur, the controller broke a final time. We had no spare controller and couldn't fix this one, so we stayed in a hotel on the side of the road and went home the next day.
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I am proud of how far we went and feel like I learned a ton about electricity, solar power, and using tools. I hope that with some changes (a new controller, using a pmw instead of an mppt, and utilizing the load to send power to both the motor and the battery) I can do the trip again and make it to San Francisco without breaking down. This is the greatest number of consecutive hours I can remember spending with my dad, and it was a super fun project to do with him. I learned a lot and I am glad that my dad went all in to do this project with me.
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