Wednesday, December 11, 2013

Bring On The Next Semester!

It's the middle of December and the semester is winding down. Next week, final exams will be over and the shop will be more or less quiet for a few weeks. That's when preparation begins for the spring semester. Our Hybrid Electric Vehicle class is held then, so now is the time for reviewing last year's curriculum and looking for ways to improve on last year's lessons. One addition for the next crew of recruits will be the "hands on" experience of re-purposing lithium ion batteries that were used in diesel hybrid buses. We will be working with Grand Valley State University in the development of curriculum as it pertains to reconditioning and reusing these batteries. The class will disassemble the battery packs and, after the fore mentioned testing and reconditioning, reassemble the cells into battery packs that will be mounted in our Small Shock mini bike project (and possibly the AntiPrius project, too!). Another activity that I would like to include would be the construction of permanent magnet electric motors. There are a few science kits out there that include all of the needed parts for this endeavor. This would deepen the students' understanding of both motors and generators. Class starts on January 13. Stay tuned!

 

Monday, May 6, 2013

Almost Finished

Small Shock has been through the shake down phase, disassembled, sent out for powder coating and reassembled. The remaining work involves finishing details of the wiring and some more minor tweaks. The regenerative braking system is now controlled via a thumb switch on the handlebars; this week we will integrate it into the regular drum brake which is activated by a hand lever. The semester is over and classes have ended, but our students are eager to return and finish the project. The next post will include much more detailed information concerning our project. Stay tuned!

Haedlight has been converted to LED



LED rear tail/brake light



With big brother AntiPrius
 

Thursday, April 11, 2013

"Small Shock" Electric Mini Bike Project Update



"Current" news: it's alive! Our HEV class project "Small Shock" is up and running. Let's start with some information concerning what makes it go: five Werker 12 volt, 44ah batteries wired in series provide the 60 volts for power. Turn the key and listen for the contactor to close; now the current is flowing to the Sevcon Gen4 inverter/controller unit. Twist the throttle and this unit inverts the direct current of the batteries to alternating current and sends it to the 3 phase AC motor. This brushless permanent magnet motor is capable of putting out up to 19 horsepower. Clean, quiet horsepower. The sensation of driving the bike is quite different then a conventional mini bike; totally smooth and almost silent. The only noticeable noise is from the chain - and an almost imperceptible low whirring sound from the tires as they roll over the pavement. A Cycle Analyst digital dash provides data concerning battery voltage, energy usage, speed, distance and regenerated energy that has been directed back into the batteries.

A few notes about the work that remains to be finished before the end of the semester: final tweaks to the wiring - it is important to us that the wiring harness look as professional as possible. This should be finished soon. The DC to DC converter must be installed. That will convert the 60 volts from the battery pack to 12 volts. This will be needed to run the headlight, taillight and brake light. We may also need to add cooling fans to the heatsink for the inverter. Once these tasks have been finished, the students will disassemble everything and the frame will be shipped out to a local company for powder coating. The same bright green that adorns the AntiPrius project will be applied. The wheels and some of the accessories will be painted silver. We have only three weeks to finish and it will be close. If you are in the Northern Michigan area on May 19th, Small Shock may be seen at the NMC Barbeque, along with the AntiPrius and our hot rodded GEM electric car. More info about the Barbeque here




Thursday, March 21, 2013

Failure Analysis






The above image shows a failure of the highest degree when it comes to Hybrid Electric Vehicles. The dreaded P3009 (High Voltage Leak Detected) trouble code could be attributed to several problems. Battery modules leaking small amounts of electrolyte, problems within the air conditioning compressor and a few others come to mind. Burned out stator windings in a 2001-2003 Toyota Prius drive unit are a distinct possibility as the miles roll up. A Prius model year 2004 or newer uses a boost converter to increase voltage to MG2, which is the main drive motor within the transaxle. Higher voltage means that less amperage is needed to drive the wheels. Less amperage means less heat is generated within the motor, leading to longer life. Click on the picture for a closer view; you will see that the windings were hot enough to burn off the insulating coating that prevents the individual wires from conducting current amongst each other. This condition seems to be less common to Prius owners who have regular maintenance performed at the recommended intervals. The transmission fluid that Toyota recommends has been improved since the original Gen 1 Prius was released. The newer fluid is better at providing some insulating qualities that the earlier fluid lacked. Repairs for this condition involve either new stator assembly from Toyota (figure on spending around $2500.00 parts & labor) or replacing the entire transaxle with a used unit ($1500.00 parts and labor). There is no way to predict whether a used unit is "near failure" without partial disassembly, and warranties on used parts are often very short and may not include labor.


Tuesday, March 5, 2013

Let's Get Rolling!


The Small Shock project is underway with help in the form of a grant from the NMC Foundation. Actually, I should state that it has been underway for a number of weeks! The Spring 2013 Hybrid Electric vehicle class has been in session since January and we are well into our studies. An update to our project is long overdue. Our plans to re-purpose the Heathkit mini bike frame were dashed when it was obvious that the poor condition of the frame (rust from the inside and a major crack at an important structural point) would not provide the necessary strength needed to support the batteries. A trip to Actron Steel yielded a bundle of 1" X .095 wall tubing and the game was on. We are fabricating a new frame from the ground up. It is our good fortune to have a few experienced fabricators in our class! The main structure has been bent up and welded together. This paves the way for some improvements on our original design. The engineers at ElectricMotorsport.com provided awesome support when it came to recommendations for our drive system. The new plan calls for 5 AGM style batteries. Our lab is now blessed with a Sevcon Gen 4 controller/inverter and Mars 19 horse power, 3 phase AC permanent magnet motor. 


Also in the mix is a DC-DC converter to drop the 60 volts down to 12 volts for the few accessories that are in the plans. Another feature will be the Cycle Analyst digital dashboard and battery monitor. This unit will calculate watts, amps and volts instantaneously as they are drawn from the battery. It will also allow us to check net values since the batteries were last charged as a sort of fuel gauge to determine remaining battery pack energy. Speed, distance and regenerative values will also be logged.

This first week of March should see our frame nearly complete with the motor brackets fabricated and installed. Once we have procured our batteries we can begin work on the framing in which the batteries will reside. Small Shock has generated a lot of interest in what goes on in the HEV lab here at NMC and has hopefully inspired some of our students to think about getting involved in the next generation of electric transportation.