Introduction: The original objective of the SunDragon data acquisition team was to design and implement a data acquisition for SunDragon V and VI. However, due to the bleak outlook of Drexel University’s solar car team, our team decided to redefine the goal of our Senior Design project. The new objectives is to first correctly re-wiring the electrical systems of the schools Electric Vehicle and second to incorporate a small data acquisition system including the use of Cruising Equipments e-meter to gather battery pack; voltage, current, and current-hours and dump the data onto a laptop in the car. Someone outside the University acquired the electric vehicle, a converted 1984 Honda CRX, as an incomplete project car donated to the Drexel electric Vehicle team. The car was about ninety percent complete with the low voltage electrical system requiring the most work, along with some mechanical re-design. Our primary goal is to make sure that all the wiring in the high and low voltage systems are correctly wired with the proper documentation of schematics and manuals. When the wiring is correct we will be able to attempt to charge the batteries and test drive the car to make sure everything if functioning properly. We also need to test the batteries to ensure they will hold a charge. After the car is working we will mount the e-meter in the center of the dash to display battery status. The changing goal of the team defines a logical overall financial decision and the ever-changing world on engineering. After reassessment of the initial problem it was found that this would be a reasonable change with the time remaining in the term. Thus making it feasible to complete the re-wiring and implementation of a small data acquisition system. Work on the Electric Vehicle After obtaining working space in the basement of the Hess labs we were able to bring the car to Drexel to begin our assessment of the Electrical systems. Both the High and the Low voltage system were already installed from the original conversion project. However, these systems were not finished and not correctly installed in the car. As a result we needed to document and trace all wiring previously installed. Using this information we were able to decide the best approach fixing the electrical systems. We first started the high voltage system. The High Voltage Electrical System The High Voltage system contains the following parts: o 10 12-Volt batteries; 4 up front and 6 behind the drivers seat. o DC-Motor with Curtis PWM Motor Controller o Potbox to control speed via the original gas pedal. o 30A Breaker Box o K&W B-20 Charger for 120-volt, 20-amp line o Contactor o E-meter for voltage, amp and current readings o Shunt to measure current across the battery pack. The first objective of our work on the EV car was to ensure the proper setup of the high voltage system. Tracing each of the high voltage cables throughout the car we were able to determine that the system with the motor, motor controller, contactor, and battery pack was properly setup. A Honda CRX requires the motor run in a clockwise direction and from the motor documentation we determined that the motor was correctly wired (See Appendix?). Another issue that needs to be resolved with the system is the placement of the two batteries, which are currently located directly behind the front bumper. The current location for these batteries is not safe and poses a great safety risk if there was a collision involving the front end. There for a good position would be in the trunk with the six other batteries once the heavy duty springs are installed. However, the battery placement will be left to the to the mechanical design team, who will determine the best battery positions based on weight distribution throughout the car to ensure a safe vehicle. The battery charger is also not hooked up to the batteries, but the wiring in place in the engine compartment. There are four wires that need to be attached to the battery pack once the low voltage system is complete. The final issue is the ten batteries in the car have been sitting outside without having maintained a charge for several years. As a result many of the batteries individual voltages are around 6-8 volts each, which might result in not being able to be re-charged. If that is the case we are going to have to either purchase new batteries or use the batteries donate by Lockheed Martin. Low Voltage Electrical System The low voltage electrical system contains: o DC-to-DC converter o 12-Volt auxiliary battery o Vacuum pump o Vacuum pump switch o Original electrical system (Lights, horn, turn signals, stereo, etc…) o Ignition Switch o 2 relays to control the contactor and potbox o Light indicators One look at the low voltage system and one can see that there were many components improperly wired. Initially, we did not have a good low voltage-wiring diagram to use as a reference, so we decided to trace the existing system starting at the dc-to-dc converter. Tracing wires off the converter we quickly released that the inputs from the battery pack to the converter were improperly wired, both going to the positive terminal of the contactor. Next we moved to the contactor, which was only wired to a switch located on the center console, not the key switch and no power source. At this point in the tracing process we decided that we should just rewire the entire low voltage system using a wiring diagram from Michael Brown’s Convert It for reference. We started rewiring the low voltage system in the 7th week of classes by start with the key switch relay and the poxbox relay as seen in the diagram in appendix? The potbox relay controls the contactor by allowing the contactor to close only when the gas pedal is pushed down. The use of this relay is a safety measure that allows the flow of current to the motor only when the pedal is used and not just by turning the key. The key switch relay activates the low voltage system when turned to either position one or two allowing for the potbox relay be triggered when the gas pedal is pressed. We mounted the two relays on the firewall close to the divider panel for easy access to all the components. We were able to test out the key switch and the potbox relays by attaching a 12-volt battery to the low current system and a 12-volt battery to the high voltage terminals of the contactor. We turned the key causing only the low voltage system to work, but not closing the contactor. Next, stepping on the gas pedal caused the micro switch in the potbox to close causing contactor to close, thus completing the circuit. The original person to do the conversion removed the connection in to the original 12-volt system in the engine compartment. Therefore we need to figure out the correct lines off the OEM fuse box, which will allow us to supply power to the headlights, turn signals, brake lights, horn, etc… Once the OEM 12-volt system is working we will be able to connect it into the low voltage system through the dc-to-dc converter outputs and a chassis ground. E-meter The E-meter is being used to take measurements of the High Voltage system in the electric car. With the use of a 500-volt prescaler we will be able to monitor the voltage, amp, and amp-hours via a LCD panel mounted in the center of the car’s dashboard. We are going to use an existing hole in the center of the dashboard, which is wide and deep enough to mount the e-meter in a smoked Plexiglas top to cover the hole. Also, there is a serial port located on the back that can be used to download data to a computer or other storage devices. Currently we have the E-meter running with the 100V prescaler on a test bed with a 12-volt battery is being used to power the E-meter. It is measuring a total of 50V from a battery pack wired in series and with a shunt to measure the current. The output of the prescaler is 10-volts on the e-meter without setting up the e-meter to multiply by a factor of two. We do not have enough batteries currently at a high enough charge to measure something that the e-meter without the prescaler cannot handle. The 500-volt prescaler was tested to ensure that it is functioning as designed. The e-meter measures the total voltage across the entire battery pack by hooking it up in series with the High Voltage circuit. It also measures the current using a shunt, which installed on the firewall and attached in series to the high voltage circuit. Since the e-meter is going to be installed in the dash we will need to run a serial line cable from the back of the e-meter to a port on the dash in order to hook up a laptop at anytime. Budget The following is the budget from last years EV senior design team with the addition of the costs incurred this year. Item 1984 Honda CRX chassis 9” Advanced DC Motor CurtisPMC Motor Controller CurtisPMC Potbox Albright Contactor Current Shunt Cruising Equipment E-meter w/ 500V prescaler Sevcon DC/DC Converter K&W Battery Charger K&W Battery Charger Booster Power Brake Vacuum Pump 50mV Shunt 10-12 Volt Batteries Car relocation Miscellaneous Total Cost Cost $1150.00 $1623.00 $906.00 $77.00 $165.00 $22.75 $300.00 $580.00 $675.00 $195.00 $285.00 $30.00 $1500.00 $155.00 $300.00