disadvantages are low specific energy, poor cold temperature performance, and a high intolerance to total discharge. Lithium-ion batteries come in various lithium chemical configurations with their apparent advantages and disadvantages. The advantages of lithium-ion are high specific energy, high specific power, high-energy efficiency, good high-temperature performance, and low self-discharge. Some of the disadvantages of lithium-ion is it has low shelf life, high internal resistance, more costly and they are not as durable as the alternatives. Nickel-metal hydride (NiMH) is advantageous because it has the second highest energy density of the other three batteries. NiMH also has the highest specific power. Unfortunately the disadvantages to NiMH batteries are that it is not as commercially available as lead-acid or lithium-ion and it has poor efficiency. The final battery option, the Zebra, meets the specifications to provide the necessary power to the electric vehicle motor, but the issue is that it must be heated up to operating temperature before it is of any use. Because it operates at such a high temperature, cold weather does not affect the performance of this particular battery. below shows different batteries and their respective energy and power properties. This table shows the most critical characteristics for all the batteries being considered for the project. This data is used in and for a more visual comparison. Table 1 - Battery Comparison Battery Specific Energy (Wh/kg) Energy Density (W-h/L) Specific (W/kg) Cost ($/kWh) Lithium-ion 100–250 250–360 ≈250–340 $400 Lead-Acid 30–40 60–75 180 $150 Nickel-Metal Hydride 30-80 140-300 250-1000 $250 NaNiCl (zebra) 90 160 155 $300 Nickel-Zinc 90 Nickel-Iron 60 Zinc-Chlorine 90 Sodium-Sulfur 150-300 Aluminum-Air 300 and are based off an average family car that is assumed to use 12kWh and obtain the range of 0-60 miles of distance traveled. The range is a function of power (kWh), so as the range increases the kWh required will increase proportionally as seen in . By comparing the traction from the charts, the two batteries that stand out are the lead-acid and the lithium-ion. In terms of weight as a function of range, as seen in , lithium-ion has a clear advantage by requiring
will recommend that the driver turn off the automobile completely and check the system for short circuits. Interlocks for safety The microcontroller will monitor the clutch switch, door interlock and the break switch to verify they are all SAT during the first initialization after the ignition key is turn on. If all are SAT condition, then the microcontroller will take inputs from the Voltage pedal and enable the motor drive electronics. There after the switch inputs are not active until a reset of the ignition switch. If the switches are UNSAT then the microcontroller keeps motor drive controls off until a SAT condition occurs. below is a sealed metal box that contains the sensor/motor electronics and the IGBT power switches attached to a heat sink with fans. A metal cover is located over the circuit card to help shield it from the EMI generated during the pulse width modulation motor switching. The fans will be controlled from the controller as mentioned above. Figure 44 – Controller Black Box Sensors & Thermal Control The design of the temperature monitoring and control is based upon the sensor selection. Whether the sensor is analog, digital or one-wire will determine the overall configuration and additional parts that might be required. shows a comparison between six temperature sensor devices. It can be easily decided that economically the TMP20 would be the best selection with the widest operating temperature range. Despite this factor the additional components for an analog to digital converter design would make up for its benefit. In terms of the best component to reduce the number of wires included in the wiring harness, from the rear of the vehicle to the controller in the front, would be the DS18S20/DS18B20. The only disadvantage of this component is that its relatively new technology that may not have a large number of application engineers that are able to assist in malfunctions. The final option is the TMP03 sensor which despite its high cost provides a reasonable temperature range and can be further interfaced due to its open collector output. This temperature sensor requires a 4.5 to 7 V input which can be regulated from the 12V battery. 16 - Temperature Sensor Comparison Part Number Type Temp. Input Voltage Output Cost LM335 Analog -40°C to +100°C 1.8V to 5.5V Voltage $1.35 TMP20 Analog -55°C to +130° 1.8V to 5.5V Voltage $0.87