P18463: Water Powered USB Charger

Integrated System Build & Test

Table of Contents

1 Team Vision for Integrated System Build & Test Phase
2 Design Changes
- 2.1 Turbine Blades
- 2.2 Housing & Waterproofing
3 Mechanical Test Results
- 3.1 Dynamic Waterproof Testing
- 3.2 RPM Motion Capture and Optimization
4 Electrical Test Results & Updates
- 4.1 Generator & Voltage Regulator Power Output
- 4.2 Soldering Results
5 Rod Anchor & Accessories
6 Bill of Materials
7 Risk Assessment and Problem Tracking
8 Updated Project Schedule & Milestones
9 Design Review & Demo Materials
- 9.1 Demo Videos
- 9.2 Review Outline

Team Vision for Integrated System Build & Test Phase

The goal for this phase was to integrate, assemble, and test the device as a full system. This was a full phase of iteration; the entire sealing system was redesigned using the principles of a boat housing box, an enclosure meant to house two lip seals, lubricant, and packing material. Additionally, we are now addressing weight distribution concerns that are being brought about by the larger blade design but have multiple ideas of making it happen during the final phase. Fortunately, the electrical equipment is still working as expected and we were able to perform a fully functional system test outside of the water.

Design Changes

Turbine Blades

The turbines blades were made much bigger. The pitch angle on the blades was also decreased to increase the RPM. The size was made bigger to deal with the extra torque required to rotate these blades at this angle. The rounded tips have also been removed to preserve the most power we can from the limited area we are allowed to expand the size to. During testing it was also found that the blade angle was the opposite of what it should have been. The issue has since been corrected.

New Turbine Blades

Housing & Waterproofing

As previous attempts to waterproof the system were unsuccessful, changes were made to the approach required to waterproof the system. Now, two lip seals are being used. There is also a narrow section with high tolerances and an enclosure built of aluminum is used to house all these things. The enclosure is filled with graphite grease that should help lubricate and waterproof the system. From initial testing this system seems to be waterproof and the motor will now be placed inside to run final tests.

Stuffing body with lip seals

Stuffing body only

Mechanical Test Results

Dynamic Waterproof Testing

Issues regarding buoyancy arose during testing. While the system does seem to be waterproof, more weight was needed hence steel will be machined and placed within the enclosure. The changes and lower part of the assembly has been shown below.

Steel Body

Steel body within enclosure

RPM Motion Capture and Optimization

This section is currently being tested.

Electrical Test Results & Updates

Generator & Voltage Regulator Power Output

Before having all components soldered and put inside the housing assembly permanently, we tested them outside on their own to see if we they gave good results. The results obtained show everything working just as expected and it was demo'd to our guide and customer. The USB power meter made obtaining power measurement results much easier since now we don't have to use a multimeter and have too many connections. Multimeters have high internal resistance which affect our reading and USB power meter simply plugs into our cable from one side and the power bank plugs in from the other side of our meter. The power meter gave us a good reading after the blades hit the rpm speed of around 480-500 rpm, but the power bank starts charging at around 430 rpm.

USB Meter Example

Electrical Testing Setup

Shown below in the table are the results obtained. As can be observed, voltage starts being measured around 450 RPM and increases steadily as the RPM rises. Around 650 RPM the voltage plateaus at just about 5V. This is due to our voltage regulator which will keep the voltage from going above 5V.

Voltage Vs. RPM Graph

Soldering Results

Soldering the USB ports into the cable and then covering the connection points with heat shrink wrap was the next step and it was completed successfully. The cable successfully transmits power from one end to the other with negligible losses. This was observed when the turbine and the whole device were packaged in housing and tested using a drill machine. The electrical components functioned just as expected and this proves that the cable connections are securely soldered.

Soldered Connections

Rod Anchor & Accessories

Most of the rod and anchoring materials should arrive either late this week or early next week. As soon as they do, we will begin assembling the rod as outlined in the procedure below. Most of the work is simply time consuming machining, but appears to be a simple assembly. We will also be taking a closer look at the anchoring mechanism on the tripod to see if we can minimize rotation in the other direction. Exact measurements for drill sizes and cutting will be taken once the items arrive.

The Rod Assembly Procedure can be found here: Rod Assembly Procedure

Bill of Materials

The updated Bill of Materials accounts for everything that is in or expected to be in our possession within a week. At this point, we do not see the need for any new items that are not on this list. This may be subject to change as we make last minute iterations on the device in the final phase before Imagine.

The current Bill of Materials can be found in the following link: Updated Bill of Materials

Risk Assessment and Problem Tracking

While this phase of iteration provided the team with a ton of knowledge and solved some of our major problems, we are still uncovering and managing more as the project moves forward. The important risks and problems we are managing and tackling are highlighted below.

Important Risks

The Risk Assessment Document can be found here: Risk Assessment

Problem Tracking

The Problem Tracking Document can be found here: Problem Tracking

Updated Project Schedule & Milestones

This is the final breakdown of what will need to take place before Imagine. Additional details are within each item on Teamweek. A snapshot of the schedule can be found below: