Solar4Africa: Forever Battery

PCB Design and Supply Chain Analysis
Project Overview
Solar4Africa is small social enterprise that seeks various solar electricity technologies to provide low-cost solar electricity to low income Malawian villages in Southeast Africa. My task was to research the Lithium Titanite (LTO) battery chemistry and design a PCB that would provide "forever battery" to Malawian villagers' rice cookers.
My Contributions
First, I performed system testing given a battery management system (BMS) and found problems with the original design. Using the BMS on the PCB, I learned to assemble different parts (charger and load) and understand how the system works on a high level.

Then, I worked on designing the next design of the system that sought widespread use and mass production of boards. I designed the schematic, laid out components and wires that would connect on an actual PCB using CAD. Using Eagle, a PCB design software, I finished simple tasks such as designing a PCB trace shunt resistor and layout for power transistors with a heat sink.

I also explored the supply chain management sector for specific parts that go into the PCB and presented my analysis to the team on a weekly basis.
Figure 1. Sample of a Soldered PCB
System testing is important as it allows us to emulate tasks as Malawian villagers would such as using and charging the battery. With other members, I instructed and guided peers to understand the system, run cycles of charge/discharge and record the battery voltage on the microSD card. That way, we were all aware of the basic electronics and more advanced technical details such as transistors, digital circuit design, and PCB layout. For our deliverabe, I created a testing report that included all of voltage log files, error reports and improvements to better the system on a high level.

PCB layout in Eagle CAD helped me analyze the circuit schematic and demonstrate my understanding in electric thermal management and circuit. In the future, I hope to further explore the thermal simulation in FEA and analyze the structure/behavior of the system.
Solar4Africa: Forever Battery
Project Lead
Jan 2023 — Nov 2023
Figure 2. System Testing Setup
Figure 3. Crystal Oscillators Schematic
Figure 4. System Log File Sample Values
Jun (Hyunjun) Kim
Linkedin
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