Alternative Energy Bicycle System Choluteca, Honduras 17 March 2012 24 March 2012 Service Learning Engineering College of Engineering The Ohio State University 20 April 2012 Students: Stephanie Tsavaris Elizabeth Schweizer Nirupa Manohar Brandon King Trip Resident Directors: Dr. Roger Dzwonczyk (Clinical Associate Professor, Dept. of Anesthesiology) Miriam Simon (PhD Candidate in Engineering Education) (Not shown in picture) 1
Index Introduction... 3 Location Information... 3 Project Participants... 3 Project Details... 3 Project Background... 3 Scope of Work... 4 List of Deliverables... 4 Brainstorming ideas... 4 Research Performed... 4 Results of Initial Calculations... 6 Concept Designs... 6 Prototypes and Testing... 7 Prototype... 7 Testing Summary... 7 Final Design... 8 Photos, Calculations and Models... 8 Cost Analysis... 9 Materials... 9 Sustainability and Maintainability... 10 Project Schedule... 11 Pre-Trip Timeline... 11 In-Country (Honduras) Timeline... 12 Gantt Chart... 12 Project Details While In Honduras... 13 Bicycle Stand Details... 13 First Alternator and Associated Components... 15 Second Alternator and Associated Components... 22 Conclusions and Future Recommends... 23 References... 27 Appendix A: Tables... 28 Appendix B: Figures... 30 Appendix C: Sample Calculations... 32 Appendix D: Instruction Manual... 37 2
Introduction Location Information Our team traveled to Choluteca, Honduras as part of a Humanitarian and Service Learning Engineering effort through a course taken at The Ohio State University. Choluteca is in the southern region of Honduras between El Salvador and Nicaragua. During the trip we implemented our Alternative Energy Bike Stand project, which we spent the past 10 weeks researching and designing. We departed for Honduras on Saturday, March 17 th and returned to the United States on Saturday, March 24 th. Project Participants Brandon King, Civil Engineering Historian Nirupa Manohar, Chemical Engineering Team Recorder Elizabeth Schweizer, Industrial Systems Engineering Schedule Coordinator Stephanie Tsavaris, Mechanical Engineering Team Leader Project Details Project Background A means of alternative energy was sought out for use in Choluteca, Honduras. The way our team planned on harnessing energy was by using a bicycle. Our bicycle system was to serve not only as an alternative energy source, but also to encourage the students and community in Choluteca to exercise, which is something that is not in their usual routine. A stand and attachment were designed to hook up to a standard bike. The system is portable so that it can easily be moved to the location where it is needed. It is also able to fit the standard bike model 3
found in Choluteca so that anybody s bike can be attached to the stand. The bike will be used to power any object or service that requires a quick and easy energy source. Scope of Work The bike will be used to provide a quick energy source. It will primarily be used to charge a battery, which will then be able to charge small electronics such as cell phones, tools, etc. We have also ensured that the design of the stand and attachment is not too complicated. The simplicity allowed us to build the device easily, and also allow for the students and citizens in the city to replicate it. List of Deliverables The overall purpose of our bicycle system was to design and setup a stand, which can be hooked up to a bike. The energy created from riding the bike can then be used to charge batteries. Not only does it serve as an alternative energy source, but it also serves a dual purpose of encouraging exercise and physical health. Documentation and instructions have been provided for continued use since we departed. The bike can also be used as a teaching tool for the students at the vocational school. Brainstorming ideas Research Performed Once the Scope of Work (SOW) was defined, we held a brainstorming session about the bike stand that would have to be fabricated and what components were necessary to charge a battery. We first started with a brief literature review, mostly utilizing online websites such as scienceshareware.com and YouTube. We then looked at pre-existing bike stands, and talked with 4
people who have had previous experience in working with the power components. Because our project needed to be easily replicable, we also talked with a member of the Honduras community to learn what materials are common to the area. From our brainstorming and researching efforts, we learned that the community has access to scrap metal and some members of the community are skilled in welding. This fact guided us to choose metal as the primary material and welding as the fastening mechanism for the bike stand. Figure 1 is an example of the typical designs we encountered in our research. Figure 1: Common design for a bike stand For the power components, our main decision was choosing whether to use a car alternator or permanent magnet for the generator. The car alternator was selected because the community would have easier access to the part even though the alternator requires about 1800 revolutions per minute (rpm) before it will start working (Scienceshareware). Another reason was alternators have internal regulators which automatically regulate the voltage at 14.8V DC regardless how fast an individual pedals. 5
Results of Initial Calculations Initial calculations were performed to determine what size battery was needed. From our SOW and Equation 1, we determined an 18 AH, 12V battery would be sufficient. where, Time is how long the wattage would be available P is the power or desired output wattage V is the voltage Further calculations were performed to determine what gearing ratio and cylinder dimension would be needed based on the 1800 rpm requirement from the alternator. Without the exact specifications of the alternator, assumptions were made to obtain a general idea. The pedaling speed values were taken from Erica Leigh s article on Livestrong.com (Leigh), and the diameter of the cylinder was determined given the bicycle wheel was 26 inches and the bike was a single speed. Table 1 summarizes the calculated results. Table 1: The necessary dimensions given the 1800 rpm requirement Pedaling Speed Gearing Ratio Cylinder Diameter 60 rpm (casual) 30:1 0.87 90 rpm (improves pedaling speed) 20:1 1.3 From Table 1, the ideal cylinder diameter would be 0.75 inches. It is a standard size and will include participants who may be new to cycling or those who desire to pedal at a casual rate. Concept Designs Our next step was focused on designing the bike stand. We used a rectangular base with two vertical posts to lift and support the rear bicycle tire. The vertical posts were reinforced with diagonal members to form a forty five degree triangle on each side. A classmate s bike was used 6
to collect the general dimensions of the stand. We wanted to lift the tire two inches off the ground to ensure there would be enough clearance for the wheel to rotate. The width of the stand was chosen to be wider than the width of the bicycle wheel for two reasons. The first was we wanted the added stability of having a wider base, and the second was we wanted to keep the dimensions as simple and uniform as possible. For the attachment mechanism, two threaded rods were used on each side to allow for varying widths of rear bike axles. A coupler, which will fit over the nut on the bicycle s rear wheel axle, was drilled out and attached on the medial end of each rod. The mechanism was locked in place by tightening two nuts back-to-back. Prototypes and Testing Prototype Figure 2 shows the prototype we built from our initial design. Because the purpose of the prototype was simply to confirm the dimensions, we used wood for the material instead of metal. Figure 2: Prototype of bicycle stand Testing Summary Using the prototype, we checked our initial height estimate by holding a bike at the location where it would sit in the stand. From this, we learned that the holes through the vertical 7
posts needed to be a little higher to lift the tire to the desired height of two inches. Figure 3 shows the solid model and the critical dimensions of our final stand design. Figure 3: Final bike stand design Final Design Photos, Calculations and Models The final set of initial calculations we performed were to confirm the structure would not fail when used. The two vertical posts and the triangle supports were checked for yielding and buckling. Since some members of the Honduran community would be building the frame before we arrived, we didn t know exactly what type of metal would be used for the frame. The failure analysis was performed for wood with the assumption that what they build out of scrap metal would be stronger. Sample Calculations for the failure analysis can be seen in Appendix C. The assumption that no one over 500 lbs. would be using the stand was also made. After the analysis, we determined that the stand would not fail in the vertical posts or the triangle supports. The calculated values can be found in Table 3, in Appendix A. 8
Additional and alternative views of the bike stand can be found in Figure 3 located in Appendix B. Figure 4, also in Appendix B, shows how a bike tire would be attached within the bike frame. Cost Analysis Two options were initially considered for the design of the stand; one with a car alternator and the other using a permanent magnet motor. As part of the decision-making process, cost spreadsheets were created for both options. Table 4 in Appendix A shows a price comparison between the two options. When summing up the electrical components necessary for each choice, the option of using an alternator resulted in a cost of $92.15 and the permanent magnet motor option yielded a cost of $156.70. The final design chosen utilizes the alternator. Table 5 in Appendix A shows the costs for all items purchased for the project. The total amount spent was $212.65, with $183.67 belonging to pre-trip expenses and $28.69 devoted to cost of items purchased in Choluteca. The expenses in Choluteca were shared between all projects taking place; therefore, the bike actually had $0.00 in project expenses in Choluteca. Without shared expenses, the bike project had a specific cost of $161.38. Materials The materials necessary to complete the project can be split into two categories: The first are items we brought with us to Honduras, and the second are items we used while in Honduras. Items Brought with Us Alternator Battery (20 Ah) Inverter 9
Loctite 5/8 Threaded Rod 5/8 Nut (x2) 5/8 Threaded Sleeve (x4) Multimeter Cylinder- Connection between the bicycle tire and alternator Tools for Wiring/Electrical Fasteners Metal Rails for the Sliding Mechanism Items Used in Honduras Wiring/Fasteners Bike Stand (Was prefabricated by the workers at the vocational school) Power Drill Materials for Power Components Layout o Flat plate, support structure, etc. Sustainability and Maintainability This system is sustainable due to the fact that there are plenty of bicycles in Honduras. It is a very common form of transportation in Choluteca, so it will be easy for people in the community to utilize the stand. The chosen design is also affordable and since we are using the cylinder design and not the belt design, it is easily replicable for the locals. This project also allows for a form of energy which is not dependent on fossil fuels, but powered by humans and is also environmentally friendly. 10
There are many important aspects to keep in mind with respect to the bike stand. First of all, the system should be able to acceptably perform its intended function. Safety is also very important for the system. The stand should be closed off and all electrical components should be protected so as not to harm others or the system itself. The stand should also be very stable and secure to ensure safety for those riding. The system will also be used as a learning tool for the vocational students and easy enough for them to understand all the components and connections. Project Schedule Pre-Trip Timeline January 4th - Introduction and initial project discussion 11th - Project management and form project teams 18th Presented and edited project proposal drafts 25th Worked in project teams to start design plans February 1st - Continued project work in teams 8th - Project design review - short team presentations 15th - Team projects continued 22nd - Team projects continued 29th - Project presentations March 7th - Final project wrap up 17th - Departed Columbus and arrived in Choluteca 11
In-Country (Honduras) Timeline March 18th - Beach day 19th - Inspected pre-made bike stand and began assembly 20th - Worked on alternator tray fabrication 21st - Continued fabrication and electrical set-up 22nd - Assembled for the last time, but ruined the alternator so began securing the 2nd alternator 23rd - Finished implementing 2nd alternator and electrical set-up and departed for Tegucigalpa 24th - Returned home Gantt Chart 12
Project Details While In Honduras Bicycle Stand Details The bike stand built for us was ready upon arrival with the exception of a few needed modifications. Figure 4 shows the original stand. Figure 4: The bike stand that was prefabricated The first problem that needed to be addressed was that the two holes in the vertical posts were drilled too small. The vocational school and the local hardware store did not have a one inch drill bit so instead of drilling, we used an arc welding machine to create a larger hole. Because the 5/8 coupler was going to be welded into the hole, the precision from a drill was not needed. The second problem that occurred was the line between the two vertical posts was not parallel to the crossbars on the bike frame. This meant the bike would have to be angled, which, in effect would make the couplers that fit over the nuts on the bike not line up. To align the two welded couplers, we moved one to the side of the vertical post. We also welded a support structure underneath to help hold the coupler in place. Figure 5 shows the modification. 13
Modified Post Figure 5: The modified vertical post The stand was finished by attaching metal rails onto the frame, adding handles and a locking mechanism onto the threaded rod, and securing a coupler on the end of the threaded rod. The handles provided an easy way to rotate the threaded rod. We detached the vertical handles from the bicycle and used them as handles for the rod. The clamp was lined with rubber due to a slight difference in diameters. When the threaded rods were positioned to hold the bicycle, they were held in place by two tightened couplers in a row. Originally a wrench was needed to tighten the second coupler, but we were concerned that finding the appropriate wrench would be an inconvenience. To avoid having to use a wrench, we decided to add a handle to the second coupler by welding a bolt with an unthreaded section at the top. This handle provided a quick and easy way to ensure the bike would be properly secured in place. The end coupler on each threaded rod slid over the nut on the rear axle of the bike to hold the bicycle in place. A nut was tightened behind the coupler and Loctite was used on the coupler threads to keep it from moving. All of these features are shown in Figure 6. 14
End Coupler Vertical Handles Locking Mechanism Figure 6: The mechanism used to hold the bike With the bicycle frame complete, the stand was first tested by holding a bike alone and then with a rider. The stand did not have any visual deflections when just the bike was being held or when the rider was stationary on the bicycle; however, when the rider pedaled, the modified vertical post rotated back and forth. Originally, the support underneath the couple was only welded on one of the three sides in contact with the vertical post. We welded the other two sides and the modified vertical post no longer moved. First Alternator and Associated Components In order to make a connection between the bike tire and the alternator, a tray that attaches to the stand was fabricated to hold the alternator. The tray was made out of c-channel scrap metal found at the vocational school on the first full day of working on our projects. We then cut the c- channel and, with the help of school staff, welded pieces to the ends so that the tray was now a box. Next, scrap pieces of metal were welded to the tray to serve as vertical posts that the alternator would be attached to. We then completed a few tests back at Larry and Angie s house that brought up an initial set of issues. First, we realized that the vertical posts were welded on backwards and had to be removed and re-welded. Second, the cylinder that attaches to the alternator shaft was wobbling too much. In order to fix the instability, we decided to add a 15
vertical post on the side of the cylinder opposite from the alternator, and then drill a hole so that a greased bolt could go through the post and into the cylinder. Another issue that came up was that the cylinder was coming loose from the alternator. We first tried wrapping duct tape around the shaft of the alternator in hopes that it would produce a snug fit with the cylinder. This method worked, but we believed there were better options. Next we tried wrapping a copper wire around the shaft and soldering it to even out the threads. When the copper wire was wrapped around the shaft twice, it was too thick and the cylinder would no longer fit on the shaft, so the first layer of wire was removed. With just one layer of copper wire it still was not an ideal fit. The cylinder was pushing against the wire too much and the wire was not staying in place so we removed the wire and went back to the tape. We thought that vinyl tape might have the thickness we needed, so we applied a layer to the shaft. The cylinder ended up cutting through the tape and ripping it apart. After these trials, we decided to just stick with the duct tape. The next day we used a hand drill to drill a new hole into the cylinder. We also took off the vertical posts that the alternator attaches to and welded them back on correctly. An L-shaped piece of scrap metal was cut out and welded to the tray to serve as a vertical support for the cylinder on the opposite side of the alternator. One hole was drilled into each of the vertical posts that the alternator attaches to and two holes were drilled into the post that stabilizes the cylinder. Figure 7 shows the fabricated tray with all three posts and drilled holes. 16
Vertical Post Hole #2 Hole #1 Support Posts Figure 7: Fabricated alternator tray The first hole in the vertical post, shown in Figure 7, was for a greased bolt to go through and into the newly drilled hole in the cylinder. The second hole was for another bolt to go through to keep the first bolt from sliding out. We also had to drill out the threads in one of the holes in the alternator so that the screw could fit through it. Holes were also drilled on the sides of the tray to attach to the stand. After struggling for a while with creating those holes, it was brought to our attention that the auto mechanic classroom at the school was equipped with a drill press. With the help of staff at the school, the drill press was used to drill four holes, two on each side, so that the tray could attach to the rails already installed on the bike stand. We also cut out rubber from a scrap inner tube and super glued it to the cylinder to increase friction. A stand made of scrap wood was completed as well to hold the battery and inverter. Next, we started to fasten the alternator to the tray and assemble all the parts. We found out that in order to make solid contact between the bike tire and cylinder we would have to drill new holes in the tray because the current holes did not line up with the railing. 17
Using the drill press, we were able to drill a new set of holes into the tray. This new set, shown in Figure 8, finally made it possible for the tray to line up with the railing system and attach properly. Figure 8: Alternator tray with drilled side holes to connect to rails To help increase the snug fit the cylinder had with the alternator, we removed the fan from the shaft of the alternator. We also cut half of the bolt heads off for both bolts that connect the alternator to the tray. This cut allowed the bolt to lie flush since the diameter of the head was forcing the screw to be inserted at an angle. To help resolve the issue of the cylinder coming loose from the alternator shaft due to vibrations, we applied Loctite to the setscrews. However, mechanically there was still too much vibration in the system and the rubber around the cylinder also started coming off. We worked on setting up the electrical components and saved the vibration issue for the following day. For the electrical system, we first determined what each wire controlled on the alternator. Figure 9 shows that the alternator we used had two wires: one to control the internal regulator and one to transfer the current being produced from the alternator to the positive terminal on the battery. 18
Switch Internal Regulator Ground Wire Hot Wire Figure 9: Alternator Wiring A switch was installed so that when the bike is not in use, the alternator s internal regulator would not drain the battery. To ground the system, we added the ground wire from the alternator casing to the negative side of the battery. From the battery, an inverter was used to go from direct to alternating current. With everything wired and the alternator and tray attached, we completed another round of testing. The gear ratio achieved was 22 to 1, which means one full rotation of the pedals causes the cylinder to rotate 22 times. We found out that electronically everything was working and using an ammeter we determined a net current of half an amp was being produced. Based on the equation below, it would take 40 hours to fully charge the battery. The following day we did several things to eliminate the vibrations. First, we welded two small, scrap pieces of metal to the vertical post to help support and stabilize it, as shown in Figure 10. 19
Figure 10: Welded pieces to stabilize post Also, we added washers to serve as spacers in multiple areas that contained gaps, as demonstrated in Figures 11 and 12. Figures 11 and 12: Spacers After reapplying super glue to the rubber and attaching it back on to the cylinder, we also zip tied it as an additional precaution, as seen in Figure 13. Figure 13: Cylinder with rubber super glued and zip-tied 20
We were then ready to re-hook everything up. First, the two bolts were inserted to attach the alternator to the tray. Figure 14 shows one of the attachments. Figure 14: One of two bolts that attach the alternator to the tray A greased bolt on the opposite side of the cylinder went through the vertical support and into the cylinder. Another bolt went through the other side of that support to lock the greased bolt in place, as indicated by Figures 15 and 16. Figures 15 and 16: Greased bolt locked in place Four total screws then attached the tray to the railing. While waiting to get the wiring connected again we tested for vibrations and finally had success. Everything mechanically was working smoothly with little to no vibration. Due to limited wire available at the hardware store in Choluteca, ideal color wiring could not be used. During the final assembly, the hot and ground wires were switch on the battery 21
terminals and a spark ensued. Since we installed a switch, normally this should not be an issue; however, at some point in the few minutes prior, the switch had accidently been bumped or turned to the on position. This caused the regulator to short circuit our alternator rendering it useless. After talking with Larry, head of the vocational school, we decided to try and implement the second alternator we brought. We were concerned with having limited time because a new tray to hold the new alternator would have to be built in one day. Second Alternator and Associated Components Since the second alternator we brought with us was slightly smaller in width than the first alternator we had to create a new tray to house it. We followed the same relative design and instructions that we used to build the first tray. One quality we were able to improve upon was the width of the tray. The first tray left gaps between the ends and the railings. We measured the length of our new tray accurately so as to negate any unnecessary spaces in the assembly. We used new pieces of scrap c-channel at the vocational school as the primary material, and support posts were again welded to align with the alternator. Before leaving the school for the day we were able to weld the sides of the tray on and also get the two vertical supports welded. With only a half-day to finish working on Friday we had a lot of work to do. We found another piece of scrap metal to serve as the vertical piece to stabilize the cylinder and welded it to the tray. Using the drill press and the help of workers at the vocational school, holes were drilled in the sides of the tray (2 on each side) and through each of the two of the three vertical posts. We were unable to access the third support post with the drill press or hand drill because of the shape of the tray. After considering our options, we quickly decided to use the arc welder to melt a hole just large enough for the bolt to fit through. The new tray is shown in Figure 17. 22
Figure 17: Fabricated tray for second alternator Bolts were then put through the holes to connect the tray to the rails and the alternator to the tray. Spacers were used in locations where there were unavoidable gaps in attachments. After all pieces were assembled, all the electrical units were connected, and testing began. An ammeter and voltmeter were connected to the circuit in order to determine the amount of current being generated. Several people rode the bike at varying speeds but there was no change in current and a reasonable voltage was not able to be generated. From the testing, we determined there was something wrong with the alternator which meant the battery could not be charged with it. Our next step would have been to purchase a used alternator in Honduras and implement it into the system, but we were out of time. Conclusions and Future Recommends The electric bike project we left with the vocational school is shown in Figure 18. 23
Figure 18: Electric bike system Unfortunately it was not fully completed. Because of the problems we had with the two alternators we brought down, they will need to purchase another alternator and wire it to the battery and switch. Instructions on how to wire the system and calculate the output power have been sent to the vocational school along with an operation manual. These documents can be found in Appendix D. Depending on the new alternator dimensions, they may also need to modify the tray that secures it to the stand. The rest of the system has been tested and is ready for use when the new alternator is installed. The system will work with the current design, but to charge the battery faster, the system can be converted to a belt-driven mechanism instead of the current drum-driven mechanism. Using a belt will increase the gear ratio because it will go from the 26 wheel to a pulley which has a smaller diameter than the current cylinder. A higher gear ratio means the alternator shaft will rotate faster, producing more current to the battery. Table 6 summarizes the increase of the alternator shaft rotation depending on the size of the pulley. 24
Table 6: Comparison between the cylinder and different pulley diameters Item Connected to Rpms of Alternator Shaft Percent Gear Ratio Alternator Shaft (Given an input of 60 rpms) Increase Current Cylinder (3 ) 22:1 1320 rpm -- 2.375 pulley diameter 27.8:1 1667 rpm 26.3% 2 pulley diameter 33:1 1980 rpm 50.0% It is noticeable from Table 6 that even the slightest decrease in diameter can have a large effect on the rotational speed of the alternator. The table only shows a couple of examples, but Equations 2 and 3 will determine the gear ratio and the rpms of the alternator shaft for any pulley diameter. where the 66 value is from the bike s gear system is the diameter of the pulley in inches where the Rpm user is how fast the user is pedaling the Gear Ratio is determined from Eq. 2 A downside to converting the system is the bicycle is no longer a portable system. Currently, any student with a 26 wheel is able to hook their bike up to the stand. If the school is willing to designate one bike for the system, then we would recommend improving the amount of power produced. Another thing the school would have to consider is finding or purchasing a belt and ensuring it has the appropriate tightness. To implement the belt-driven mechanism, the rear tire would be removed, and the belt would run along the wheel. The belt would connect to the pulley that is already on most alternators. The concept can be seen in Figure 19. 25
Belt Pulley (Generator.com) Figure 19: The belt-driven set-up with the pulley Our goal is to have the auto mechanics department work on this as a class project. It will be a great hands-on learning experience, and by having the students involved, there is a better chance that they will take ownership of the project. Ownership is essential to whether or not the project is a success and properly maintained. 26
References "Bicycle Powered Generator." MattShaver.com. W3C, n.d. Web. 5 Feb 2012. <http://www.mattshaver.com/bikegen/index.htm>. Ebenezer, Job. "STANDARD BICYCLE WITH PEDAL POWER ATTACHMENT." Technology For The Poor. Technology For The Poor, n.d. Web. 5 Feb 2012. "Free Plans." Scienceshareware.com. Scienceshareware, n.d. Web. 1 Feb 2012. <http://scienceshareware.com/pedal-power-build-your-own.htm>. Leigh, Erica. "The Limitless Potential of You."Livestrong.com. N.p., 14 Jun 2011. Web. 2 Mar 2012. <http://www.livestrong.com/article/268174-how-fast-should-i-ride-a-stationarybike/>. PedalPowerGenerator.com. Pedal Power Generator LLC, n.d. Web. 6 Feb 2012. <http://www.pedalpowergenerator.com/ 27
Appendix A: Tables 28
Table 3: Results from calculations versus the design limits Vertical Posts Triangle Supports Frame Model Design Limits Good/No Good Stress 31.25 psi 2901 psi Good Buckling Force 125 lbs. 285,000 lbs. Good Stress 22.1 psi 2901 psi Good Buckling Force 89.39 lbs. 285,000 lbs. Good Table 4: List of component costs for Permanent Magnet motor and alternator option Option Item Unit Cost Permanent Magnet Alternator Generator - Treadmill Permanent Manget -90 V, 1.25 Hp $40.00 X - Alternator-1993 Honda accord $23.45 - X Inverter - 400 W Cobra CPI $26.70 X X Battery- 12 V, 18Ah Battery $42.00 X X Blocking Diode- 10 Amp $5.00 X - Charge Conroller - 10 Amp $43.00 X - Total Cost $156.70 $92.15 Table 5: Costs for all items purchased 29
Appendix B: Figures 30
Figure 3: Alternate views for the final design of the bike stand Figure 4: Wheel and bike stand 31
Appendix C: Sample Calculations 32
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34
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Cylinder Gear Ratio and Alternator Shaft Output (rpm): 36
Appendix D: Manuals 37
Electric Bike Construction Manual 38
Mechanical Set-Up 1. Assemble stand according to design specifications. 2. Assemble bike connectors a. Weld couplings into holes on bike stand Coupler b. Drill out ½ of the threads on end couplings so it fits over the nut on the bike axle Drilled Threads 39
c. Assemble threaded rod Handle to Adjust the Rod Locks the Coupler in Place Locks the Handle in Place 3. Create Cylinder Figure 1: Coupler with a handle to lock the rod in place a. Drill out hole in cylinder to fit over alternator shaft Alternator Shaft Hole 40
b. Drill and tap 2 holes for side set screws Set Screws c. Drill hole opposite of alternator shaft i. Hole should be approximately 2 in. deep d. Apply rubber to cylinder surface with super glue 4. Alternator-Cylinder Assembly a. Slide cylinder over alternator shaft b. Apply Loctite to set screws and tighten keeping cylinder centered on shaft 41
5. Drill holes in bike stand to add side rails and attach side rails with bolts 6. Fabricate tray to hold alternator and cylinder a. Use scrap metal to build tray to fit between side rails b. Add supports to secure alternator c. Add 3 rd support opposite of alternator to stabilize cylinder i. Drill holes in support to: 1. Hold the screw going through cylinder 2. Keep cylinder screw in place Stabilizes Support 7. Alternator and tray assembly a. Place alternator-cylinder assembly in tray b. Insert bolts into alternator holes and corresponding supports 42
i. Insert washers if needed and tighten c. Insert bolt through 3 rd support and into cylinder d. Insert perpendicular bolt to secure cylinder bolt (Shown in Step 6) 8. Tray and rail assembly a. Drill holes in sides of tray to align with rail holes i. Attach bike to stand (Refer to bike attachment manual) ii. Align tray so cylinder and bike tire have firm contact iii. Mark 2 holes each side of the tray which line up with railing holes 43
b. Insert bolts for each hole i. Secure with 2 nuts ii. Use washers if gaps are present and tighten 9. Attach bicycle to stand a. Align bicycle in center of stand b. Extend threaded rods until end coupler just fits completely over rear axle nut c. Tighten coupler with handle to lock in place 44
Electrical Set-up 1. Wire switch to alternator a. Attach switch to bike b. Secure wires to bike 2. Wire alternator to battery From Switch Wire to Battery Positive Terminal Ground Wire to Battery Negative 3. Ground alternator 4. Connect inverter to battery 45
Operation Manual 46
1. Have one person hold the bike with the back wheel in the center of the cylinder. Figure 1: Bike Centered over cylinder 2. Have two additional people tighten each handle only until the rod is in contact with bike and couplers are secure over nuts on bicycle. Be careful as to not over tighten handles. Also worth noting is that Loctite was used on the couplers threads on each rod, and the couplers do not need to be adjusted any. Figure 2: Handle used to tighten rod 47
Figure 3: Coupler properly fitting over nut on bicycle Figure 4: Coupler properly fitting over nut on other side of bicycle 3. Tighten modified couplers with bolts welded on to lock rods in place. Figure 5: Modified coupler with welded bolt 48
4. Place a small, spare piece of wood under front wheel to help increase contact between back tire and cylinder. 5. Turn switch on. Figure 6: Front wheel with wood underneath it Figure 7: Switch 49
Figure 8: Coupler properly fitting over nut and modified coupler with welded bolt tightened and locked-in on the left Figure 9: Entire rod with all components (handle, modified coupler with welded bolt, and coupler that fits over bicycle nut) 50
Power Calculations 51
Calculation to Determine the Battery Size Needed: where, Time is how long the wattage would be available P is the total power (total wattage) V is the voltage of the battery Example: Calculation to Determine How Long it Takes to Charge the Battery: where, AmpHr is the battery rating Net Current is read from an Ammeter Example: How to Determine the Gear Ratio: *Gear Ratio: It s the ratio of output to input, and it s also known as the mechanical advantage. Example: A gear ratio of 15 means when the rear tire of the bicycle rotates one revolution, the alternator shaft rotates 15 revolutions. 52