Leon Papadopoulos

Prof. Hecht

Physics 114

Due: May 16^th, 2008

Research Paper: How Electric (Hybrid)Cars Work

An electric car is very beneficial for our environment and to our economy as well. Many people may ask how a hybrid car functions and works. A hybrid car is a vehicle that contains more then one power source, such as an electric power source and internal combustion engine or an electric motor with battery and fuel cells. Fuel cells act as energy storage. A fuel cell manufactures a continuous repeating electric current from the oxidation of gasoline. More and more people will begin to drive hybrid cars as time goes on because of the high prices of gas.

There are many similarities between an electric car and a gas powered cars. The average consumer would not notice many changes in the interior of the two cars; but under the hood is where the most noticeable manipulations are. Under the hood of an electric car is completely different then a gas motored car. The main thing that you see when you open the hood is the controller. The controller’s job is to send power from the batteries to the cars electric motor. When you push on the gas petal, there is no gas involved, the petal controls variable resistors, and they tell the controller what to do. In most cases with an electric car, LED acid batteries are placed under the floor. When you put the key in the ignition and turn it, you are connecting the batteries to the controller under the hood so that you can begin your drive. Also in electric cars, there is a small electric water heater for heat. A vacuum pump is used to charge the brakes. An electric car contains a lot of high voltage. The main controller under the hood can produce up to 50,000 volts of power.

Another interesting aspect of hybrid cars is the braking system. The braking system in these cars is known as regenerative braking, where the electric motor applies a resistance to the drive train which causes the wheels to slow down. The wheels then act as a generator. Here is where energy is stored in the battery until it is used by the motor. In gas motored cars energy is usually wasted and lost when braking. This is another reason in why electric cars are much more efficient then gas motored cars. Also in these cars is a device that automatically turns the car on or off while it is idling. This device shuts the car off if it is as rest for a certain period of time. It restarts and turns on when the petal is pressed again. This is also another great way that the electric car saves energy. Another advantage of these electric cars is that they also have decent acceleration. The electric motor helps the engine in speeding up. This is useful for going up hills or passing someone in a lane. This allows a smaller engine to be more efficient. Granted these cars aren’t built for speed and don’t have 300 horsepower, but they will do the job and most importantly get great mileage.

A DC controller is used to connect the battery to the motor. The voltage received by the motor from the battery depends on how far the pedal is pushed in. If the pedal is pushed all the way down, the motor will receive the full amount of voltage from the battery. If the drive released the pedal the voltage given to the motor would drop down to zero. The pedal is hooked up to potentiometers. A potentiometer is basically just another resistor in the car. These meters tell the controller how much power they are supposed to supply to the engine. The potentiometer can deliver any amount of power to the engine depending on how hard the pedal is pushed. It can range from full power to anywhere in between to absolutely nothing. Everything else in the car is powered by a regular 12 volt battery like in gas cars. They control radios, fans, and head lights. Most of these electric cars are equipped with automatic transmissions. The gear box contains a small switch which delivers a signal to the controller when you are switching gears. The gear box is very similar to that of a normal car, it still has a “Drive mode” and “Reverse mode” and various other gears such as neutral and park as well. There is also a charging system right where your gas tank would be on a gas motor car. This area basically does as it name says. It charges the battery so you travel further. Some electric powered cars are equipped with more then one charger. If there is more then one charger in a vehicle one charger is usually a normal 120 V charger, and the other would be a magna-charged inductive charging paddle.

<<120/240 Volt charging system

With all the positives of owning a electric car, there are still many draw backs. The battery of the car only last about three to four years. The battery alone for these types of vehicles weighs over one thousand pounds, which is almost one third the weight of a normal sedan. These batteries on average take about 12 kilowatt-hours of electricity for a short trip of about 50 miles. On average for electric cars, it takes over 12 seconds to reach about 60 miles per hour so it is definitely lacking some power.

Electric cars created much less pollution then gas powered cars. They are very environmentally friendly as well. During a summer season where gas prices sky rocket it is almost logical to sell your gas guzzling SUV and pick up an electrical car. It cost only around less than five cents per mile rather then paying around twenty cents per mile on a car that gets about 20 miles per gallon. It cost only about one dollar to fully recharge the car completely. –But another weak spot of recharging is that the battery will eventually die and run for a short period of time over time. Eventually you would have to change and replace your battery. A replacement battery for an electric vehicle cost around two thousand dollars. On average these batteries last between 20 and 30 thousand miles.

There are two primary types of motors used in electric cars, an AC and DC motor. The basic different between an AC and DC motor is the amount of volts that are fed to them. A DC motor works on any voltage from 96 to 192 volts. If it is an AC motor it is “most likely a 3 phase AC motor running at 240 volts AC with a 300 volt battery pack.” (Howthingswork.com) A DC type motor is usually more inexpensive to install rather than an AC motor. The good thing about a DC motor is that you could “over-drive” them. Basically what that means is that you can get more power out of them if you tune them. This will generate in greater acceleration. An example of this is if a motor normally accepts 20,000 volts it could be “over-driven” up to 5 times and would be able to accept 100,000 volts of power. This would increase the horsepower by 5 times. It would not be wise to always have your motor on over-drive because eventually it would fail from being over worked. It is a great feature to have though for short distances. On the other hand the positive side of having an AC motor in an electric car is that it has a “regan” feature. This feature basically means that it has a generator inside the motor which helps charge the battery over time. This feature only applies as you apply the breaks to slow down the car from any velocity.

>>Diagram of AC Motor

>>>Diagram of DC Motor

The main setback with electric cars has to do with their batteries. As listed previously there are many problems with batteries and their lifespan. There is an alternative battery that is available for sale known as the NiMH battery. This battery last for about ten years and you can travel double the distance with it as well. The one flaw with this battery is that it cost about 10 to 15 times greater then the LED-acid battery. These batteries range from twenty to thirty thousand dollars rather then the two-thousand it cost for the LED-acid battery. As time goes on the NiHM battery will go down in price and will be able to compete with the acid battery. Another huge problem with the standard acid batteries is the inconvenience of it. It takes around four hours to fully recharge it and weighs over one thousand pounds. If this was compared to a gas car, it takes around just around three minutes to fill up your tank and you are good to go for a much bigger range of miles.

Charging these types of vehicles is also a very interesting. In order to charge these cars you need a charging system. The main purpose of these charging systems is to pass electricity to the batteries at the fastest rate possible and to monitor the batteries during the process so that they are still functional after.