Motion powered battery

Overview

How often have you been going about your day, and your phone suddenly dies when you aren’t near an accessible outlet? You have to drop whatever you’re doing and completely change your schedule to get your phone to charge. This dilemma stems from our society’s constant reliance on electronic devices and the inconvenience of finding a consistent power source. This is what inspired the idea for our engineering design project.
For our engineering design project, we will be creating a motion powered battery. While there are some of these on the market with various designs, our motion powered battery will utilize the model of a shake flashlight. Ideally, we will be able to generate enough stored power to charge an electronic device (i.e. a phone) for a substantial amount of time.
Our three person team will design and build a magnet charging device that uses magnetic forces to generate an electrical current through a wire. We will be using an Arduino to measure the power output and determine if there is a need for a capacitor/resistor. Once the battery is charged, we hope to build power output terminals from the battery so that we can use it to power other things. We will put the entire design into a case to protect the external pieces from breaking.

Weekly Log

Team Members

• Katherine Laue
• Steven Schlau
• Henry Roberts
• John Fordice(TA)
• Denise Mell(Instructor)

Objectives

• Generate voltage using changing magnetic fields from the movement of neodymium magnets
• Connect the generator to a rechargeable battery that would store power to be outputted later to a wide range of devices
• Encapsulate design using 3D printed pieces for more efficient power generation

Barring Major Set-Backs:

• For presentation purposes, create LED visual to represent the storage of power in battery

Design

The visual design of our project will mainly consist of a tubular apparatus made of a PVC pipe section with a Teflon lined interior and a neodymium magnet that slides through the inside. Outside, there will be a copper wire coil wrapped around the tube which will be connected to the rechargeable battery, potentially with a resistor and/or capacitor between them. The battery will then have output terminals itself so it can change other devices in addition to being charged. Ideally, the battery will not have to be disconnected from our model to be able to charge other devices. This entire tubular design will be held in a more attractive encasing so as to look more desirable to a potential consumer.

Single Pipe Diagram

Electrically, our design will generate power as the magnet runs through the copper coil. Electrons will flow through the coil and then run into the battery where they will be created into chemical energy. In order to encase our pipes and wires, we will create a wooden box that will have 4 rectangular holes on both widths in order to slide shelves in. We will also have a wooden rectangular top that will be connected to the box by tape or a lever. In order to keep the pipes stable in the box, we will 3D print 4 shelves with 6 holes to slide pipes in. 3D printing the shelves will allow for more accurate holes which will make the ability to create and store power more precise.

• Initial Presentation: https://docs.google.com/presentation/d/1kpignFUBYeWpITa3DcwuG8xqo7b4M8Ykv34dZw7oDcM/edit?ts=5a84f158#slide=id.p

Challenges

Initial Assessment

Our main challenge is more of a potential issue with the overall motion powered set up. Most motion powered devices only require small power outputs such as crank or shake flashlights. Existing motion powered devices such as AMPY's Move need vigorous movements such as running to generate power in a reasonable time span. Our device may need to be shaken very hard or for a long period of time to generate enough current and electrical energy to
a) charge the battery even a little
b) generate enough charge in the battery to use it to power other devices.
Once we have built our design, we hope to refine it to make it smaller. This could be a potential challenge as we will want to still generate a similar power output but have a smaller design that could be more attractive to a consumer.
We will need to experiment with different types of Teflon (sheets, spray, tape) to find the material that allows the magnet to slide through the tube with the most ease.

Updates as of 4/20/2018

Our initial design was one large tube wrapped 250 times with wire. When we shook this design, it outputted 0.5 volts. We were pleasantly surprised that our original design worked but the design itself was too rigid. One of our primary goals was to take our original idea and make it smaller (easier to store). We ordered the smallest pipes and magnets we could find and planned on putting 12 pipes into our new design. What we didn't anticipate for was the fact that magnets are attracted to each other. The smaller our design got, the closer the magnets were to each other and the charges interfered with each other.

Box with 6 pipes

There are ways to block attraction of magnets but the cost alone does not make sense in the case of our project. In order to have the magnets be less attracted to one another, we used 6 pipes instead of the original 12 pipes. We were still able to get a reasonable amount of power but not as much as we originally hoped for.
Another problem we encountered was converting from AC to DC. When we were doing our original calculations we were measuring in AC which is useless if you want to charge an electronic device like a cellphone. When we converted from an AC current to a DC current, some of the current was lost which is common. We did not have as much voltage as we initially anticipated.
Lastly, when we were creating our presentation, we realized that our project did not have a way to demonstrate what was occurring internally. After talking to Professor Mell, we decided to use an LED light connected to an Arduino to give a visual of power being created and stored. Even though the LED did not have to do with out project and would not be on the finished product, it showed the people we presented in front of that our project was doing exactly what we said it was.

Gantt Chart

Ethical Concerns

In terms of ethical concerns, our project does not have any pressing issues but there is the possibility of a safety hazard. Our project deals with wires and electricity. The box we created to encapsulate our design is not waterproof. If someone was using our product outside or in a backpack and it was raining, there is the possibility of electrocution. Our product does not generate a huge amount of power but this possibility brings to light some concern.
In addition, our design right now is impractical. It is very bulky and could cause problems if someone is trying to hold it while exercising. Also, if someone has it in their backpack they could have some back pain arise from the weight. Our next goal is to concise our project using smaller pipes and magnets thus making the shelves and overall design smaller. This would mean there is less weight and less likelihood of a customer having a problem.

In the end, my partners and I believe that the benefit of this device far outweighs the potential problems. The Motion Powered Battery allows people to charge their phone even without an outlet. If someone's phone died on a hiking trip and a problem arose, they would be able to call for help after using our design. In the future, we want to create an even smaller design but also a container that is water proof to fix these ethical concerns. For now however, our project is functional and allows customers to charge their phone just by shaking the box. This provides safety as described above and time. 

Budget

• PVC pipe - [link] - $14.54

• Wire [link] - $8.66

• Teflon (Different Types)- [link] - $9.09

• Neodymium magnet [link] - $17.66

• Rechargeable battery [link] - $9.99

• Box Container(Wood)- $4.99

• Capacitor [link] - $0.99

• Electrical tape [link] - $4.50

• 3D printed shelves - provided by Systems Laboratory

• Arduino - $24.20

Total: $94.92

Final Design and Solutions

3D Printed Shelves

Shelf top view

Shelf bottom view

We 3D printed two sets of 2 shelves, each with 6 holes to put the PVC pipes between. Each shelf was 3.5 inches long, 2.5 inches wide and 0.3 inches in height. In order to have the shelves hold the pipes, we created holes that did not go all the way through. Each hole had a radius of 0.34 inches and a depth of 0.25 inches (0.05 inches left of solid depth). As we talked about in our updated challenges, we did not account for the attraction between magnets. Instead of using all 6 holes and pipes, we ended up only using three pipes in each set of plates. On the left side of our box, we had our pipes be in the top-left hole, the bottom-middle hole, and the top-right hole. In order to further prevent attraction through the shelves, we placed the right side pipes on the bottom-left hole, the top-middle hole, and the bottom-right hole. The shelves slid into the four slits in our box making it secure without any adhesive reinforcement. Our box design also allowed the easy removal of the pipes by sliding the shelves up and out after taking the lid of the box off. This design, especially with the 3D printed shelves, makes it very easy if any maintenance is required on the tubes because nothing is glued/taped down.

Bridge Rectifier Circuit

The shaking motion with the changing magnetic field outputted a raw AC current which needed to be converted to DC to power a battery. We built a bridge rectifier circuit to facilitate this conversion. The bridge rectifier is made up for four diodes which process the positive and negative currents, switching the negative to positive. We the added a capacitor to smooth out the voltage into a more linear fit, rather than the absolute value of a sine graph.

Neodymium Magnet

We used neodymium magnets to facilitate the change in magnetic field. The magnets slid side to side in the PVC tubes, causing a current to flow through the wires wrapped around the tubes. We experimented with different lengths on magnets in the tube, with a goal of generating the most consistently high voltage.

Results

Project Recap

We created a motion powered battery, that although requires reasonably vigorous shaking, will output voltage over 1.25 volts. We met all of our primary goals and most of our secondary goals, the main one of which that we did not meet was actually connecting the box to a battery to charge. We ended up connecting our box to an Arduino to measure voltage, and illuminate an LED accordingly. However, this proved better for demonstration purposes.

Future Considerations

• what would we change

With further refinements to our design, we should be able to achieve a higher output voltage with less vigorous shaking. Updates would include springs at the ends of each tube, a different set up to incorporate more tubes with less attraction between the neodymium magnets, smoother PVC pipe lining to lower friction, and magnets that fit better with the tubes. Also, we would like to invest in copper coated neodymium magnets, so as to prevent deterioration of the magnets. Also, we have realized other potential uses of our product, beyond just normal human movements. Our box could be mounted to a car wheel or the bars connected to a train’s wheels, thus, creating constant and vigorous movement for the box.

Final Poster