Activities
Additional research
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Concept Generation
Brainstormed many different solutions for major components of the PURE LiFe generator and evaluated the solutions utilizing decision matrices, and strengths and weakness tables.
Budgeting
Created preliminary budget listing items already purchased and to be purchased in the future.
Scheduling
Created tentative schedule narrative and Gantt chart for future tasks and milestones.
Milestones
- Initial website design completed
- Completed the Project Proposal document
- Completed the Proposal presentation
Tools
- Android Studio – For creating the Android application
- Arduino IDE – For writing code for the Arduino MEGA
- EAGLE – PCB design software used to design PCB to integrate LT3652 charge controller
- LTspice IV – Circuit simulation software for simulating the LT3652 charge controller
Design Decisions
Initial Design Decisions:
- Battery Selection – Selected LiFePO4 batteries. We made the decision using a decision matrix based on research performed on LiFePO4 versus lead-acid batteries.
- Charging Board Configuration – Selected Arduino Shield configuration. We used a strengths/weaknesses comparison table against single board configuration to make the decision.
- Wireless Connection Scheme – Selected Bluetooth. We used a strengths/weaknesses comparison table against Wi-Fi and cellular modem schemes to make the decision.
- Battery capacity: 40 Ah 4-Cell, Inverter: 12V 300W, Solar Panel: 30W. We selected these values based on the IEE/WERC competition requirements of a portable system.
Revised Design Decisions:
Team PURE LiFe acquired a sponsor, Bioenno Power, after the start of the Spring 2017 semester. Bioenno Power offered to donate batteries, a solar charge controller, and solar panel of our choosing. Based on this new development we have made the following changes to our design.
- Charging Board Configuration – Selected off-the-shelf solar charge controller made by Bioenno Power.
- Battery Capacity: 50 Ah, 4-Cell, LiFePO4
- Solar Panel: 80W Foldable Panel
Design Work
Prototype 1:
Single-cell LiPo solar charging circuit with Bluetooth connection to Android app.
Prototype 2:
4-cell lead-acid solar charging circuit with Bluetooth connection to Android app.
Simulations:
LT3652 solar charging circuit design and simulation in LTspice IV.
Final Design Parts List:
Testing
Prototype 1:
Working charging circuit with basic monitoring via the Android app.
Prototype 2:
Working charging circuit with detailed monitoring via the Android app.
Working charging circuit with basic monitoring via the Android app.
Prototype 2:
Working charging circuit with detailed monitoring via the Android app.
Challenges
Initially we wanted to design a custom charging circuit around the LT3652 solar charge controller. The amount of work required to design the circuit and the time required to have the circuit board manufactured were both more than we had anticipated. A solution presented itself when we reached out to Bioenno Power. Bioenno Power sells their own lithium battery and solar power solutions. They agreed to become our sponsor and donate parts of our choosing to us. Bioenno Power also sells complete solar charge controllers and so we decided to use one of theirs and forgo designing a custom circuit to solve our problem.