User:Criveros0248/enes100/Electric Cars

Link to project ekart team page.

Give instructor top 3 project choice list
At the beginning of class on Wednesday 10/12/2011, I decided I did not want to continue working on the Engines project. Therefore, I switched to the Electric_Cars project.
 * 1. Engines
 * 2. Art Parade
 * 3. Escher

Write problem statement
How can I build an electric go kart that illustrates the basic guidelines needed for possible intercollegiate competition?

Assign Task1
Take the electric motors out of the forklifts.

Wash the old lead-acid batteries and the motors.

Wait for parking space approval.

Transport the motors, batteries, and battery chargers in pickup truck to HCC.

Research "DIY Go Kart Forums."

Work on a design for the go kart on 123D.

Research go kart frame prices on Craigslist or eBay.

Compare actual work done to Task1
I was able to do tons of research, but little hands-on work. I still need a fully charged 12V battery to test one of the forklift motors, and a multimeter to figure out the specs of both motors.

Week1 Narrative
This week I was able to retrieve the two forklift motors out of their respective cases to test them. I also washed and cleaned the old car batteries that were donated to our project. Additionally, I researched ways on how to sell the idea of an electric go-kart to the college. I started by looking at different types of intercollegiate go-kart racing competitions. I came across numerous competitions found around the country, including the Baja SAE and Formula SAE series. These two events are the biggest intercollegiate competitions of the nation where college teams design, build, and race their exceptional creations. The problem that I found with these two competitions is that none of them include electric powered vehicles. At HCC, we might try to do a competition against other community colleges in Maryland using electric go-karts.

The basic rules/guidelines (mostly based on SAE standards) would be:
 * A vehicle with four wheels not in a straight line.
 * The vehicle must be all electrically powered.
 * It must not use more than 50V.
 * It may not achieve speeds greater than 50MPH.
 * Specs: width: 64 in., length: 96 in.
 * It must be capable of safe operation on concrete and cement.
 * It must have adequate ground clearance and traction.
 * Adjustable seating area to accommodate for multiple body types of possible drivers.
 * Batteries must be mounted and secured properly in case of a roll over.
 * Vehicle must have adequate racing lighting. (headlights, brake lights, turn signals, etc.)
 * It must have a seat belt and a kill switch.
 * It must have an adequate braking and suspension system.
 * Drivers must wear adequate safety gear (helmet, neck support, gloves, etc.)
 * It must meet all SAE construction standards (welding, machining, painting, etc.)

Along with following these guidelines, teams must also have numerous written reports outlining their design and construction processes. Along with the documentation being checked before the official competition, teams will be judged on their e-karts' design and performance on the track.

These are just some of the basic rules that a competition I have in mind must have. It is a work in progress and we would have to get appropiate authorization to continue working on a handbook with the proper rules and guidelines of this competition.

Week1 Peer Review
Peer review week 1

Assign Task2
Finish testing motors and record test run. Revive at least four batteries and record results. Continue working on selling the idea of a go-kart design and racing competition to the college.

Week2 Activities
I passed on DC motor to Jeffreycarllloyd for testing and mounting design. I manage to get 2 old car batteries partially desulfated. I also designed and welded a frame for the e-kart prototype, which could later be used to showcase to HCC to get further funding for this project.

Week2 Narrative
Motor Specifications: With these specifications, I focused on finding the speed controller, potentiometer, drivetrain. and axles for the ekart.
 * Made by GE
 * DC wound series motor
 * Current: 46A
 * Volts: 24V
 * RPM: 2000 max
 * Dimensions: 8" diameter x 14" high

Additional research during this week led me to further theoretical conclusions. In order to get the right speed controller, I needed to figure out the maximum power output of the DC motor.

Power = Current x Voltage ===> 24V x46A = 1104 watts.

Also, 1HP = 746 watts, therefore the power in HP for the motor is 1104/746 = 1.48HP.

With these results, I found an inexpensive 50A speed controller rated at 2kW that would work with the donated DC motor.

I also needed to find the torque of the DC motor to determine the gear ratio for the ekart.

Torque = [HP x 5250(constant)]/RPM ===> [1.5HP x 5250]/2000RPM = 3.88 lb/ft.

This is a decent amount of torque and should be able to produce 20MPH in the ekart with the right gearing.

I also determined the gear ratio of the ekart if I want it to achieve a minimum speed of 20MPH.

With a 10" (diameter) tire, I found its circumference ===> 10" x pi (3.14) = 31.4"

Then, I found out that a DC motor is "most" efficient at half its max RPM value.

Then, I divided the number of inches in a mile (63,360") by the circumference of my wheel (31.4"); I got 2,017.8, which is the number of inches my wheel is going to cover in a mile.

Later, to find the RPMs needed for the motor to cover this distance in a mile, I multiplied 2017.8 in/mi by (20mph/60rpm) = 672.6 RPM at the wheel.

Finally, this means that for the ekart to travel at 20mph, the wheels must spin at about 673RPM, while the motor is spinning at 1000RPM (half its max RPM value).

Therefore, the gear ratio has to be equal to (1000RPM/ 673RPM) = 1.5 ~ 3:2. This means that the gear in the shaft of the motor must be 1.5 times bigger than the gear connected to the rear live axle.

These figures are all theoretical and will only be tested once we get our experimental data from the finished ekart prototype.

During this week I also worked on reviving 2 dead car batteries. They were two 6V car batteries. I had two battery chargers laying around the house and managed to get decent results after the desulfation process outlined by Jeffreycarllloyd.

This battery had an initial voltage reading of 2.5V and I managed to increase it overnight to 4.7V.

This battery had an initial voltage reading of 1.9V and I managed to increase it overnight to 5.2V.

During the weekend of week 2, I also worked on the frame for the ekart. I wanted to make a robust frame in which I could fit inside comfortably, along with up to 4 car batteries and a 30lb. DC motor. I decided to use some spare steel tubes that I had in my garage. They were about 1.5" in diameter and would definitely give the frame the strength that it needs. I went with a 5' long and 4' wide frame to accommodate the numerous components that are to be included later. Then, I thought about the weight distribution for the ekart, and figured out that I would want the heavy motor and probably one car battery in the back. I would want the passenger and 2 more batteries kind of in the middle, and the speed controller and steering mechanism in the front. I also though about the center of gravity of the ekart. Due to its heavy weight, I went with a 2" ground clearance, which will later be tested once I weld the axles in their respective spots.

Later, because I had some free time on Thursday and Friday of this week, I practice welding some spare steel that I had. Because this was my first time welding, I figured out I could try to practice a lot. After some minor burns and long hours behind the welding mask, I was making some progress. My welding was decent enough to be used for this project. On Saturday, I cut out my metal tubes and made my welding marks and curves on some of the tubes. I used an inexpensive metal cutter/grinder to do this. I also used a drill to make the curves to facilitate the welding of perpendicular tubes.



On Sunday, I started my welding process using some clamps to hold the pieces together. One problem I soon found was that my flux wire was melting holes along the welding lines, after reading the owner's manual of the welder, I found out that my voltage and wire feeding speed were to high, I lowered this two knobs a little bit and it stopped making holes. Another problem that I found was that my curves for welding perpendicular tubes were not perfect, there were some gaps between the joining metal tubes, and these gaps caused the welder to make holes along the welding lines instead of welding the two tubes together. I had to fix this by hammering down the tubes at their point of intersection to close down the gaps and allow for better welding. Overall, it took me approximately 10 hours to complete the welding, some welding joints were horrible (those at the beginning), while others were surprisingly good (those at the end). I will later reinforce those weak spots by welding additional metal between the tubes.

Here's a picture of my frame. It's still a work in progress, that I hope to complete during week 3.



Week2 Peer Review
Peer review week 2

Assign Task3
Work on steering system design and incorporate it into go kart. Order speed controller, axles, and 3-way potentiometer. Find more batteries and continue desulfation process. Continue researching and learning more about the electronic components of the ekart.

Compare actual work done to Task3
I ordered a speed controller and a 3-way potentiometer (throttle pedal) for the ekart. I found an extra 12V battery that only needs to be charged. After researching axles and steering components for the ekart frame constructed during week 2, I became frustrated with the total cost of this project. After having spent over $100 on ESC and POT box, I decided I wasn't going to spend $200 more on steering and axle components for ekart. Therefore, I looked on Craigslist for go kart parts, and came across an inexpensive go kart frame that I simply had to buy. I made the deal on Friday and modified it during the weekend.

Week3 Narrative
After extensive research, I found out that I would need a speed controller capable of handling up to 400% of our motor's possible current (the physics behind a DC motor). The speed controller that I had found online on week 2 was not going to work. Therefore, I had to order a different one. I found this company that focuses on EV conversions called KELLY CONTROLS LLC,. I order a speed controller and a pedal potentiometer that should arrive by week 4.

I also researched the steering and axle components for our frame and was worried about the increasing cost of this project. If I were to buy the components that were needed for the frame, I would have to spend approximately $200 more. Because the goal of this project is to create an ekart prototype from inexpensive and recycled materials on a $250 budget, I decided to look online once again for go kart frames and parts. After a week of searching on sites like eBay and Craigslist, I found a private Craigslist vendor who was selling a go kart rolling chassis for $60. Because she lived close to my house, I bought the frame on Friday of week 3.

Here's a picture of the frame when I bought it:

Still, I had to make some modifications to the frame to accommodate to the project's needs. Therefore, on the weekend I welded the side compartments for the 12V batteries. I reinforced the compartments with steel sheet supplements so they can handle the heavy weight of the batteries. I also shortened the steering column and pulled the seat back to accommodate an adult sized driver. I lubricated bearings and moving connections and changed the front wheels for two that I had with ball bearings.

Here's a picture of the frame after modifications:

Week3 Peer Review
Peer review week 3

Assign Task4
Mount motor and batteries. Connect motor to axle using drive train. Work on ekart's circuitry.

Compare actual work done to Task4
I was able to get the ekart running using two 12V batteries connected in parallel to a 0.5HP DC fan motor. It was hard to connect the motor to the axle using the existing drive train on the frame, but I was able to do this using bike sprockets and chains. After more research on the ESC assembly, I ordered battery cables, fuses, and plugs.

Week4 Narrative
I was hoping to get the speed controller this week, but because it's coming from China, (I found this out after getting the tracking number a week after I ordered it!) it's going to get here by the 17th of November. Meanwhile, I researched the assembly for the ESC system on the ekart. I found out that I needed to get more parts, so I ordered online battery cables, fuses, and plugs for the circuit. Because I had some free time this week, I also decided to use a spare fan motor rated at 0.5HP and two 12V batteries connected in parallel to power the ekart. I used some bike sprockets and chains for the drive train and bolted the motor to a mount that was already on the frame. I recorded a short video of the 1st test run; it's obviously not fast because of the low power output of the motor, the low voltage source used, and the heavy weight of the passenger (ME) and the batteries. Here's a video of the ekart running at around 3MPH.

Week4 Peer Review
Peer review week 3

Start Next Project Week0 activities
Link to my 2nd project on ekart: ekart v.2