P19463: Water Powered USB Charger

Subsystem Build & Test

Table of Contents

Team Vision for Subsystem Level Build & Test Phase

All subsystems being tested. The motor output as a generator and having the turbines spun. The magnetic couplings will be tested at various distances and various number of magnets. The underwater housing will be verified that it is waterproof.

The electrical connector is tested to verify that it is waterproof. The underwater housing is created, and a manufacture plan is set. The first iteration of the blade is 3D printed. The magnet test is planned.

Test Results Summary

Magnetic Coupling Test Document

DC Motors Test Plan Document

Magnetic Coupling Test

Four iterations of the coupling magnets are verified for functionality. The four iterations include 12, 10, 8, and 6 magnet couplings. The different amount of magnets and the different spacing values are tested to find the amount of torque required to separate the two plates to become out of sync. This value will be used to ensure that the couplings will reliably turn the motor.

Magnetic Coupling Test Setup

Magnetic Testing Fixture

Magnetic Testing Fixture

Magnetic Coupling Test Results

Distance [in] 12 Magnets Torque [Nm] 10 Magnets Torque [Nm] 8 Magnets Torque [Nm] 6 Magnets Torque [Nm]
0.039 10.462 6.823 2.426 1.603
0.057 9.097 4.928 2.123 1.403
0.065 7.733 4.549 1.819 1.336
0.076 7.733 4.170 1.819 1.102
0.087 6.823 3.791 1.213 1.002
0.093 5.913 3.412 1.213 1.002
0.123 4.549 3.032 1.213 1.002

DC Motor Testing Specification

Specification Number Importance Source Function Unit of Measure Marginal Value Ideal Value Comments/Status
DC1 9 Hankscraft DC Motor Generator Power [W] 2-5 [W] 4 [W] Voltage drop to zero with DC-DC
DC2 9 DC Servo Motor Generator Power [W] 2-5 [W] 4 [W] 1 Volt output when tested with the system
DC3 9 RIYIN DC Motor Generator Power [W] 2-5 [W] 4 [W] Greater than 300 RPM required [45% voltage drop with system]

Testing Flowchart

DC Motors Testing Flowchart

DC Motors Testing Flowchart

RIYIN DC Motor Testing Results

The DC3 meant engineering requirement, at a required RPM greater than 300 RPM. The Voltage of the DC3 motor can be determine using the following equations at a given RPM. V = 0.0268RPM - 0.2768. Please Note, with a 45% voltage drop when connected to the system.
RIYIN Voltage vs RPM Plot

RIYIN Voltage vs RPM Plot

RIYIN Voltage vs RPM Waveform

RIYIN Voltage vs RPM Waveform

Exterior Components


Many housing iterations were 3D printed to verify the spacing and to ensure all the components would fit as intended before machining the final housing. The final prototype housing is made of PVC and is shown on the left. PVC was chosen because it is waterproof, where the 3D prints are less reliably waterproof. PVC primer and cement is used to join the different PVC parts.
Progress of 3D printing the housing

Progress of 3D printing the housing

The inside of the housing will hold the motor and the electrical wires. The slot where the O-ring is also visible in this photo. The O-ring is used as a waterproofing measure.

Inside of the housing

Inside of the housing

A PVC cap is used to increase the diameter of the PVC pipe to be able to include the holes needed to secure the blades, exterior magnet, and water proof seal.
Current revision of housing

Current revision of housing


The blades for the prototype are going to be 3D printed. This is the first iteration. Three blades are used because that is proven to be most efficient (found during research). The magnets will be directly glued to the blades.
Current Blades

Current Blades

Risk and Problem Tracking

Risk Assessment

Plans for next phase

Updated Schedule

Updated Schedule

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