Electrical Report
Submitted to:
Metropolitan Water District
Solar Cup Challenge 2020
February 13th, 2020
Lennox Academy, Solar Cup Team
Lennox Math Science and Technology Academy
110306 Hawthorne Blvd
Lennox, CA 90304
(310) 680-5600 Table of Contents
Team Roster…………………………………………………………… 2
Introduction …………………………………………………………… 3
Wiring …………………………………………………………………. 3-5
Block Diagrams…………………………………………………………5-7
Solar Panels……………………………………………………………. 7-10
Solar Panel Schematics…………………………………………………10-12
Solar Panel Installation…………………………………………………12-13
Emergency Stop………………………………………………………. 13-14
Bilge Pump……………………………………………………………. 14-16
Schematic Diagram …………………………………………………….16-20
Battery …………………………………………………………………20-21
Battery Mounts ………………………………………………………..21-23
Motor Selection………………………………………………………..23-24
Electronic Speed Controller…………………………………………...25-26
Telemetry and Instrumentation………………………………………..27-30
Conclusion…………………………………………………………….30
References……………………………………………………………..31
1 Team Roster:
Name Role Email
Omar Vazquez President, Team Captain [email protected]
Abel Castaneda Vice President, Team Captain [email protected]
Kary Cabrera Secretary, Team Captain [email protected]
Brandon Colo Treasurer, Team Captain [email protected]
Giovanna Medina Design Team member [email protected]
Cristian Gonzalez Mechanical Team Member [email protected]
Ricardo Miranda Electrical Team Member [email protected]
Jessica Porras Electrical Team Member [email protected]
Citlaly Chavez Mechanical Team Member [email protected]
Edgar Ruiz Mechanical Team Member [email protected]
Antonio Garcia Mechanical Team Member [email protected]
Maya Alfaro Mechanical Team Member [email protected]
Andrew Vasquez Mechanical Team Member [email protected]
Luis Galvez Electrical Team Member [email protected]
Yaired Carmona Design Team Member [email protected]
Guadalupe Garcia Design Team Member [email protected]
Mariana Lopez Design Team Member [email protected]
Kevin Hernandez Electrical Team Member [email protected]
Kate Steeper Mentor [email protected]
Bryan Monroy Mentor [email protected]
James Braslow Mentor [email protected]
Jose Rivas Mentor [email protected]
2 Introduction
Lennox Mathematics Science and Technology Academy has focused on improving the design and performance of the solar boat every year. The current design for the boat is the culmination of 4 years worth of design. The main focus this time around for the electrical team has been to continue improving the telemetry, motor, and battery system.
Last year’s telemetry system did not live up to the expectations of the electrical team. The system was very cumbersome and did not provide accurate information to the ground team. This year's system was inspired by how drone pilots use cameras and monitors to watch where and how a drone is flying. In addition to the improvement of the telemetry system, the electrical team is switching back to an older motor that was used during the first Solar Cup our school entered in
2015; the ME-0909. This is due to a malfunction that occurred during the endurance race last year with the Agni 95R motor and realizing through comparing the two motors that the ME-909 is more reliable and more efficient than the 95R. Finally, we will be focusing on battery efficiency and how to get the most out of our batteries to ensure success in both the sprint and endurance race.
This electrical report will discuss in detail the various changes to the boat discussed above and explain how these changes will improve our boat for the 2020 Solar Cup.
Wiring
This year’s boat will be using the same wiring that was used by last year’s team, which is the Matheon Select Bulk Welding wire cable and UL1007 CSA TR-64 Hook-up and Lead wire.
The team selected the Matheon wire because of its ability to conduct 600 volts and tolerate up to
3 221 degrees Fahrenheit. As can be seen in Figure 1, the Matheon wire is a highly flexible annealed 4/0 gauge bare copper conductor with a 1950 stranding insulated by an EPDM
(extremely durable synthetic rubber) jacket.
Figure 1: Matheon Select Bulk Welding wire cable
These wire characteristics, which ensure the flexibility and water/temperature resistivity, make the wire perfect for the boat’s electrical system. This wire will be used for the high current sections of the boat which include the batteries, motor, and speed controller.
The next type of wire that is going to be used on the boat’s system is UL1007 CSA
TR-64 wire made of 20 AWG wire gauge with a 7/28 stranding of prefused tinned copper wires shown in Figure 2.
4 Figure 2: UL1007 CSA TR-64 wire
This wire can handle 300 volts and 176 degrees Fahrenheit which makes it ideal for the low voltage section of the electrical system. This wire is going to be used for the control circuit between the speed controller, contactor, throttle, emergency stop , and fuses.
Block Diagram
In order to better understand the electrical system, the 2017 team made a block diagram.
It's purpose was to quickly inform all members of the different electrical components on the boat and their function. It is a generalized flow diagram that illustrates the process of how the batteries and solar panels work to convert their potential energy to kinetic. Below in Figure 3 is the block diagram made by the 2017 team.
5 Figure 3: 2017 Block Diagram
The diagram demonstrates the six main components of the boat to generate movement.
This has been a very useful diagram that has been used for multiple teams. This year to perform better in the competition we have again specialized groups to focus on the different responsibilities of the boat. The electrical team has taken multiple measures to not only gain knowledge on understanding the wire schematics, but to also to gain practical hands on experience with the electrical system. As seen in Figure 4, team members were trained to understand how the electrical system works and is wired. This is to ensure that if there is trouble during the competition all members will be able to troubleshoot the system.
6 Figure 4: Electrical Team exploring the boat
Solar Panels
A solar panel, also known as a PV model, is taking the sun's light and converting it into energy. The rays of the sun are composed of “photons” and these are turned into electricity by the solar panels. On the boat, solar panels are used as a secondary source of energy. Solar panels generate electricity by allowing photons to direct electrons away from atoms (How Do Solar
Panels Work?, LiveScience). Furthermore, solar panels are comprised of smaller units known as photovoltaic cells. Photovoltaic cells consist of semiconductors such as silicon, and metals.
While one silicon is positive (P-type), the other is negative (N-type). Moreover, an electric field is formed when electrons from the N-type silicon reach the P-type silicon after light strikes the cell. Metals conductors are attached to both ends of the cell to create current.
7 Combined with the silicone, the metal contacts generate an electric field and transfer electrons to wires. Figure 5 shows a visual representation of how solar cells generate electricity.
Figure 5. Visual on how Solar Panels work (How Solar Cells Work, HowStuffWorks)
One of the goals of the Solar Cup competition is to show how renewable sources of energy can be utilized to supply power; the solar panels component demonstrate the viability of solar energy. They are used in the competition as another source of power, and actually present during the endurance race. The 2019 solar panels where the Renogy 160W Flexible Solar Panels as shown in Figure 6 will be used for this year's boat as well.
8 Figure 6: Renogy 160W Flexible Solar Panel
The Renogy 160W Flexible Solar Panel was chosen over 2017’s choice of the GSP 80 Q Flexible
Solar Panel as shown in Figure 7.
Figure 7: GSP 80 Q Flexible Solar Panel
9 The 2017 team had 4 GSP 80 Q Flexible Solar Panels each giving 80 watts for a total of
320 watts. That will allow the system to have a reserved capacity of 7.87 amps on a sunny day, allowing the system to run at about 18 amps. This year the Renogy 160W Flexible Solar Panel will allow us to run the system on a sunny day at 17 amps because the 2 solar panels will give a
160 watts each, giving the system a reserved capacity of 8.37 amps.
Solar Panel Schematics
For the endurance race the goal is for the batteries to last 90 minutes while providing a reasonable amount of power. In order to accomplish that the solar panels must supply energy to the batteries. This year we will be utilizing the Renogy 160W Flexible Solar Panels
As per Solar Cup guidelines the voltage supplied by the batteries is limited to 24 volts; therefore, the charge controller will be wired in a parallel circuit with respect to the batteries.
This will prevent the voltage from passing 24 volts and instead increase the power by increasing the current. Figure 8 shows how the switch is connected to the panels through the charge controller. Wire A7 carries current generated from the panels to the circuit.
10 Figure 8: 2017’s wiring schematic
To wire the panels to the battery, Figure 9, provided by the product’s website, instructs how the panels will be connected with the battery and eventually the entire electrical circuit.
Figure 10 is a parts list, provided by the product’s website, that tells us what components were included with the solar panel kit.
Figure 9: Wiring of charge controller to battery
11 Figure10: Parts lists for Renogy solar panels
Solar Panel Installation
The placement and installation of the panels will be the same as last year. Custom fitted aluminum “L” brackets were used to attach the solar panels with rivets, as shown in Figure 11.
Figure 11: Aluminum L brackets
12 The Solar Cup guidelines state that the solar panels can not be more than 36 cm from the hull and be mechanically attached to the boat; to avoid solar panels coming loose and falling mid-race. To meet these guidelines placement of “L” brackets is key. Last years arrangement only had two solar panels as seen in Figure 12, demonstrating a side view of our installation.
Figure 12: Solar panel installation
Also, with the wide panels, which are 59 by 26 inches, the weight is distributed more evenly across the boat; not stressing just one side of the boat.
Emergency Stop
To begin, the function of the emergency stop is to help promote the safety of the boat once the skipper has fallen into the water. The emergency stop is a crucial device that keeps the boat safe and prevents it from bumping into an unforeseen obstacle on the lake. In order to have a functioning emergency stop, a red lanyard is connected to a button that is momentarily pressed down. The other end of the lanyard is attached to the person on board with a clip. The lanyard is clipped onto the skipper’s clothes and if this person happens to fall off the boat, the lanyard will pull the button and cut the circuit that was originally held by the pressed down button. The
13 disconnected circuit will cut the power off the motor since it no longer has a connection to the throttle, motor control, and solenoid. To add on, since this emergency stop design was previously used in 2019 by the Lennox Academy team and had found no motive to find an ulterior design, the emergency stop will be used again this year in the boat. This design, which was gifted by
Occidental College, has characteristics that allow it to function at its best, including it being water resistant due to its use of rubber and plastic on its exterior. The emergency stop that will be reused from the 2019 team can be seen below in Figure 13.
Figure 13: Emergency Stop
Bilge Pump
There are many factors that can cause water to build up inside the boat. As the boat glides through the lake, water can splash into the boat or a small leak can occur. The bilge pump is important to prevent too much water from building up in the boat. The bilge pump is the same
14 one used by 2019’s team. It has a sensor that can tell once the water levels in the boat become too high, the bilge pump starts to pump in the water and through a hose that extends outside the boat. The bilge pump is a Seaflo Automatic Submersible Boat 12V Bilge Water Pump, as shown below in Figure 14.
Figure 14: Seaflo Bilge pump
The Bilge pumps run on its own circuit, separate from the boat's electrical system. The Pump runs on a 12 volt Rayovac general purpose battery, as shown in Figure 15.
15 Figure 15: Rayovac general purpose battery
The Bilge pump and the battery are connected on their own circuit as shown in Figure 16.
Figure 16: Bilge Pump Wire Schematic
Schematic Diagram
A wiring schematic diagram is a map that shows the different paths of current, load, and paths to ground. To construct an electrical circuit, a schematic diagram is key as it shows where
16 wires are connected and which components go where. Provided by Solar Cup, the schematic diagram is seen below in Figure 17 and 18.
Figure 17: Solar Cup 2020 electrical schematic
Figure 18: Part 2 of 2017’s electrical schematic
17 As seen, certain components are clearly emphasized and leads labeled to aid in better identifying sections of the circuit.
The 2019 team also created their own electrical schematic. Their diagram is the one this year's team has focused on the most as it was the best of both worlds. Not only does it contain clear direction and component identification, it also contains information that pertains to our setup, such as wire numbering. Below in Figure 19 is the electrical schematic from the 2019 team.
Figure 19: 2019’s industrial electrical schematic
In the electrical diagram the circuit is separated into three systems: voltage sources, high current, and the motor controller system. The separation of systems happens because of the nature of the circuit which is a parallel circuit.
18 The first system, voltage sources, starts with the batteries which are in series and are connected to the A/B switch. This switch controls what source of voltage the circuit will use.
While the switch is on off the circuit will be incomplete not allowing any voltage to be drawn from the batteries. When it is turned to setting 1, the circuit draws voltage straight from the 24
DC volt batteries. When it is turned to setting 2, the circuit can only draw voltage from the solar panel controller which is generated from the solar panels. When it is turned to setting 1 + 2, the circuit draws voltage from both sources previously mentioned.
The second system, high current, begins right after the voltage source system with the
150 amp fuze; the function of this system is mainly for safety. The fuse is in place to prevent the overheating of wires and parts being damaged if supplied with too much current. Then the power contactor is connected in series with the high current fuze. The power contactor, or solenoid, is an electromagnetically controlled switch that breaks the circuit when it receives power from the emergency stop. Then, the power contactor is connected to the positive battery terminal of the speed controller. Through the speed controller, the system continues to the motor where voltage is supplied and converted to kinetic energy. Also, in this system there is an added shut resistor that is meant to be a measuring point to determine the voltage of the circuit.
The third system, motor controller system, begins with the 5 amp fuze and higher gauge wire; a diode is included to prevent backload. This leads to a variable resistor which changes in resistivity to allow for either greater or lower voltages to adjust the boat’s velocity. The variable resistor feeds voltage to the speed controller which in turn determines how to provide voltage to our motor, ranging from 0 to 24 volts.
19 Battery
The battery acts as the boat's energy source and is a crucial element to ensure the boat’s overall performance and capabilities. All teams must have a lead-acid battery due to the fact that this battery type is optimized for the boat’s electric circuit. This gives each team a better chance at performing well in both of the races. This year, the team decided to continue using the same battery as the years prior, the Odyssey PC 1100 12T battery. An example of an Odyssey PC 1100
12T battery can be seen below in Figure 20.
Figure 20: Odyssey PC1100 battery
One of the challenges with working with the boat’s batteries is maintaining equal voltage and performance. If both batteries don’t have equal voltage they will start to work at the voltage of the lowest battery. This leads to lower performance and a higher power drain. If the team wants to perform well the batteries must be tested and paired. Last year's team also hoped to test
20 the batteries but due to scheduling conflicts their plans did not come to fruition. This year the team once again plans on testing the batteries and battery testing has become one of the highest priorities. To test the batteries the team plans to take full advantage of boat outing days, days in which the team takes the boat from 2019 out for testing, by testing each battery on the water. By testing the batteries directly from the boat it ensures having more accurate predictions for which batteries will ensure the best results for both the endurance and sprint races.
This year the team once again decided to use the improved battery terminals made last, shown in Figure 21, to avoid the issues faced by the 2016 team. Without the terminals it was found that there were many problems with tightening the bolts to the battery which led to poor connections and random spasms from the motor controller.
Figure 21: Last years improved battery terminals
Battery Mounts
As per the Solar Cup guidelines, the batteries must be enclosed in a casing which is also attached to the hull. This is a safety precaution meant to prevent the batteries from falling off the
21 boat, in a worst case scenario. There have been many ideas to improve the battery casing for our boat like 3-D printing a custom case, as seen in Figure 22; however, the team last year did a phenomenal job creating a practical case.
Figure 22: Battery case concept
We want a lightweight case that doubles as a battery lifter because switching batteries is a laborious task and also dangerous when considering it's weight. The 2019 team reused an old battery case and split it into two; using orange cords to wrap around the battery, the team could mechanically secure the batteries onto the boat and lift them more easily, as seen in Figure 23.
22 Figure 23: Battery casing and lifter
Motor Selection
The ME-0909 has been selected for this year’s boat. The mechanical issues with the Angi
95R motor, last year included the motor overheating and smoking causing it to fail during the endurance race. The mechanical issues were the main cause of switching to the ME-0909 motor.
The efficiency curves of the motor being used this year are shown in Figure 24 and 25.
Figure 24: ME-0909 Power Curve
23 The efficiency curve of the Agni 95r motor used in the 2019 competition.
Figure 25: Graph displaying the efficiency curve of the Agni 95r
The endurance and the sprint race require the motore to be optimized at different currents.
For the endurance race the motore needs to be optimized at 25 amps for the 90 minute race. The
ME - 0909 at 25 amps has an efficiency of .17, at 700 watts, with 7 volts and about 600 RPMS.
While the Agni 95r at 25 Amps has 1700 RPMS, with an output of 100 Kilowatts.
The sprint race requires the Systeme to run at 150 Amps. The ME 0909 at 150 amps has an watt output of about 3750 watts and also 3750 RPMS. The Agni 95r has a watt output of 9 kilowatts and 1600 RPMS. Although the tests suggest the Agni will serve the est for both races,
2019 team had mechanical issues with the motor meaning for 2020s team. The Agni will not be used in favor of the ME 0909.
24 Electronic Speed controller
The electronic speed controller that our team agreed upon was none other than the
AllTrax SPM series programmable DC motor controller as shown in Figure 26
Figure 26: AllTrax SPM series programmable DC motor controller
Our reasoning for using this specific model would be because of the benefits that it provides and overall is the best fit for our team. One of said benefits would be how light this mechanism is compared to the rest. Not to mention how extremely compatible our chosen electronic speed controller is with our motor due to the fact that our motor draws about 140 amps while this controller can draw up to 210 continuous amps. Since the amps in our controller greatly outnumbers that of the motor it allows us to test and make sure that the motor is running at its potential while at the same time allowing us to check for amperage spikes. The reason why this SPM is extremely appealing would be because of it’s programmability meaning that we can use multiple performance curves throughout the race. This will enable us to become more
25 competitive to the people around us during the sprint and endurance race since we will have the ability to alter our performance curves with our SPM.
This SPM will be useful for both the endurance and sprint race because it helps divert a certain amount of voltage and amps to go into the motor. Due to the fact that the electronic speed controller is programmable, it was decided that we will arrange for the motor to receive a maximum of 140 amps with an rpm of 1600 meaning that the boat will run at 24 volts. Thus speed controller’s maximum amp output was adjusted using the program available from the
Alltrax. The program parameters are shown in Figure 27.
Figure 27: Program Parameters (Used from 2017’s electrical report)
26 Telemetry and Instrumentation:
Telemetry is the collection and transmission of measurements and data from one instrument to another. Using a telemetry system to transmit information to team members on the shore, our team can communicate with the skipper to reach optimal efficiency and match the graph generated from the battery load testing using a voltage versus time graph. Back in 2016, the Lennox team replied on the skipper to radio in telemetry data back to the crew. In 2017, the team attempted to use the Scooterputer™, shown in Figure 28 with a high gain antenna to provide wireless telemetry to the ground crew. However, the device was never implemented and instead the skipper would radio in the voltage of the battery using a multimeter mounted in an instrumentation panel.
Figure 28. Scooterputer™
Last year’s team proposed a new alternative for the telemetry system, which included using a first person perspective (FPV) drone camera. The FPV camera would transmit video footage of the data displayed. However, the camera could not transmit footage far enough to
27 reach a mile. Consequently, the video feed would crash once the skipper was far from range. As a result, major changes were made to last year’s telemetry system. These changes included changing the FPV camera, multimeter, and switching to the Spektrum FPV monitor.
Instead of using the previous multimeter, the camera would monitor data displayed on the
Eiechip LED Multimeter. The new multimeter, powered independently by a 9-volt battery, displays the boat’s battery voltage in red and the amperage of the resistors in blue. Figure 29 below shows the LED Multimeter.
Figure 29. Image of the LED Multimeter
The multimeter will be connected to the batteries and s the video camera will transmit the footage of the multimeter to the ground crew at a frequency of 5.806 Gigahertz. This year's telemetry system package is shown below in Figure 30.
28 Figure 30. Telemetry System Package
The telemetry system package will be placed above the motor and mechanically attached to the motor mount. The ground crew will monitor the footage from the camera using a
Spectrum FPV monitor that has an antenna attached to it. The monitor is shown in Figure 31
Figure 31. Spektrum FPV Video Monitor
29 The telemetry system was tested at Cabrillo Beach with last year's boat and had a range of 1 mile. This new system will relieve the skipper from distractions and the ground crew will be able to radio in real time how the skipper should adjust their performance during the endurance race.
Conclusion
To improve and adapt is to win. That is what Lennox Academy is striving for this year.
With the various improvements discussed in the report, our goal is to place high in the Solar Cup competition. The innovations in the telemetry system will allow better communication between the skipper and ground crew. Through our focus on battery efficiency and performance we also hope to improve the performance of our boat. Finally, previous years’ success with the ME909 motor and its better efficiency was the main drive for using it again. Although most of the electrical components of the boat are similar from other years, many of the innovations made have proved to be exceptional in allowing better function and will continue to be used this year.
We hope that with the new improvements done to our boat this year will improve the overall performance of the boat and allow us to be very competitive in the 2020 Solar Cup competition.
30 References:
Chris. (2018, January 4). Beginner – FPV System Setup Guide. Retrieved from https://dronebuildersblog.wordpress.com/2016/02/03/beginner-fpv-system-setup-guide/
How Do Solar Panels Work? (n.d.). Retrieved from https://www.livescience.com/41995-how-do-solar-panels-work.html
Toothman, J., & Aldous, S. (2020, January 27). How Solar Cells Work. Retrieved from https://science.howstuffworks.com/environmental/energy/solar-cell1.htm
SunPower. (2019, November 18). What is Solar Energy and How Do Solar Panels Work?
Retrieved from https://us.sunpower.com/what-solar-energy-and-how-do-solar-panels-work
160 Watt 12 Volt Monocrystalline Solar Panel. (n.d.). Retrieved from https://www.renogy.com/160-watt-12-volt-monocrystalline-solar-panel/
GSP 80 Q Flexible Solar Panel. (n.d.). Retrieved from http://www.giocosolutions.net/portfolio/pannello-fotovoltaico-flessibile-gsp-80-q/
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