This invention relates to a device for determining the reduced CO2
emission from an electric vehicle (hereinafter referred to as EV) as
against the CO2 emission from a standard petrol vehicle.
Although the term "petrol vehicle" is used in this specification, the said term means and includes other vehicles as well to which this invention is applicable, such as, diesel vehicles.
An object of this invention is to propose a device, which enables the user of an EV to read out on a display unit the estimated quantum of reduction in CO2 emission achieved by an EV in comparison to that of the standard petrol vehicle.
In other words this invention enables the user, and the prospective buyer of a motor vehicle,, to appreciate the benefits of the use of an EV as a replacement for the petrol vehicle, from the standpoint of environmental pollution as between an electric vehicle as against the petrol vehicle.
When a petrol vehicle is being used, every ml of petrol burnt accounts for approximately 2.36 grams of carbon dioxide released into the atmosphere. CO2 being one of the major greenhouse gases, reduction in C02 emissions is always desirable. When a person uses an EV, the consumption of petrol is avoided by utilizing energy stored in the battery of the EV to activate the motor for running the vehicle. Although the user requires electricity to charge the battery, the C02 emissions for the energy used during generation (even after considering transmission and distribution losses) is much less compared to the C02 emissions when using petrol for the same distance time and speed of travel using a petrol vehicle.
The EV vehicle accounts for much less carbon burnt for the same distance traveled as compared to a conventional petrol 2-stroke or 4-

stroke vehicle. When riding a petrol vehicle, the engine runs at some rpm and generates some torque available for traction. The rpm, torque of the engine at any point is called the operating point of the engine. The rider controls the engine by means of throttle position and operation of the engine also depends on the speed of the vehicle and the transmission ratio. The user's throttle input, therefore, substantially decides the operating point of the engine. At every operating point of the engine, the efficiency of the engine can theretbre be determined. The tbllowing reasons contribute to very high C02 emissions of petrol/diesel vehicles as against EV's
(a) fuel efficiency of small engines (even at the most efficient operating points) is much less as compared to large fossils fuel based generation units. Energy obtained from grid is also contributed by other sources. This implies higher losses.
(b) The engine operating point keeps on varying over large ranges depending on user inputs; it operates at low and high efficiency points of the engine hence increasing average fuel consumption per unit distance travelled.
(c) The engine has to be kept active while 'idling'' during which torque output is zero. This condition consumes fuel without any useful output.
In the case of a battery run EV, the vehicie does not emit any C02 during running. However, the battery has to he charged so as to provide energy to the motor. This charging is usually done from an AC grid power supply by means of a charger, The energy generated for this charging might be by means of thermal, hydro, nuclear, recyclable or a combination of these systems. This generated electricity is transmitted to a source point of consumption by means of a transmission and distribution network, the generators being run at, or near, their most efficient operating points unlike the engine of a conventional petrol vehicle. Also, their efficiency is much higher than the efficiency of the

small size petrol engine of a vehicle. In these circumstances, a user of an EV avoids a substantial quantity of fuel combustion gases and C02 being emitted into the atmosphere.
A display unit D is used for displaying the reduction in C02 by a particular EV user.
The device for determining the reduced CO2 emission from an EV as against C02 emission from a petrol vehicle, according to this invention, comprises means for determining the charging energy input to the battety of the EV; means for determining the distance run by the EV; a first base value datum storage means for CO2 emission data pertaining to a predetermined class of a petrol vehicle; a second base value datum storage means for CO2 emission data at the electric power generation source pertaining to a unit of energy consumed for charging; an electronic- controller for assessing the differenee between the CO2 emission for the EV at any given distance travelled and the CO2 emission for the petrol vehicle for the same distance travelled, and thus famishing the amount of CO2 reduction; a display unit for displaying the said amount of C02 reduction.
This invention will now be described with reference to the accompanying drawings which illustrate, by way of example,, and not by way of limitation, the layout diagram of one of possible embodiments of this invention.
Means for determining the charging energy input to the battery of the EV are provided. These means consist of means for aggregating the products of charger voltage, the charging current and the incremental time during charging which include a current sensing circuit H for detecting the beginning and end of a charging event.
The embodiment also consists of means for determining the distance run by the vehicle, which is exemplified by an odometer.

A first base value datum storage means Bl are provided for CO2 emission data pertaining to a predetermined class of a petrol vehicle. So also a second base value datum storage means B2 are provided for CO2 emission data at the electric power generation source pertaining to a predetermined class of an EV. These storage means contain, respectively, prerecorded standard data of the quantum of C02 emissions in the case of a specific petrol vehicle and a specific EY, from which data a comparison can be made in respect of C02 emissions tor the two categories of vehicles for the same distance traveled.
The embodiment also consists of an electronic controller K for assessing the difference between the CO2 emission for the EY at any given distance traveled and the CO2 emission for the petrol vehicle for the same distance traveled, and thus furnishing the amount of CO2 reduction with respect to the EV for the said distance traveled.
This C02 reduction is continuously shown on a display unit D, as the EY travels.
The Controller will include an electronic programmable. device which is capable of computation.
The display unit D will include an electronic device which can display characters or graphics to the user and can be driven directly or through an external circuit by the Controller.
The current sensor will include a known device which can measure the value of AC or DC current by giving a voltage/digital output proportional to the current. It consists of the following known means, this list being illustrative and not exhaustive:
a. Voltage measurement across shunt resistor in the
required current path
b. Hall effect sensor which measures magnetic field
produced by the current

c. Current transformer
The odometer in the embodiment includes a device which can measure the distance travelled by the vehicle by any of the following known means (this list is not exhaustive):
d. Hall effect sensors/latches coupled to rotating part
of the vehicle
e. Mechanical gear odometer
f Variable reluctance, Reed sensor g. Light dependant resistors
h. Sonic measurement of engine speed and finding distance using gear ratio
The base value datum for CO2 emission for a petrol vehicle of a particular class will include baseline figures obtained fiom a standard source which tells the quantity of C02 emitted by a petrol vehicle in the class for every kilometer of distance travelled for a standard driving cycle.
The base value datum for C02 emission pertaining to an EV of a particular class will include baseline figures obtained from a standard source which tells how much C02 is emitted into the atmosphere at the generation source for every unit of electrical energy consumed at the end point of distribution.
Charger efficiency is the statistical averaged ratio of usable chemical energy added to the battery to the energy consumed by the battery charger from the electricity grid during a charging interval.
When the vehicle is connected to a charger for charging its battery the energy input to the battery is measured by means of continuously aggregating the products of charger voltage, the charging current and the incremental time under consideration. Charger voltage for a system is assumed to be a constant DC voltage. Charging current is measured by

current measuring means. The device may include a sensor H and/or a circuit system to detect the beginning and end of a charging event. For every unit of electric energy' consumed e.g. one kWh, the electricity generation baseline is used to decrement the C02 savings and the same is displayed to the user.
When the vehicle is running, the distance covered by the vehicle is obtained by distance measuring means e.g. odometer. For every unit of distance travelled by the vehicle under consideration i.e. the EV, the reduction in C02 is aggregated as per the vehicle emission baseline for that class of vehicles and the same is displayed to the user.
The display unit to be used for displaying the reduction in C02 emissions will include any display type ranging from simple dot-matrix type LCD display to graphic display.
The total carbon reduction will be taken as the quantity of C02 that would have been used by a base line vehicle for the distance travelled minus quantity of C02 emitted to charge the battery in the electric vehicle.
Units of C02 reduced are m measure of mass such as kg. pounds, tonne.

We Claim:
1. A device for determining the reduced CO2 emission from an EV as against CO2 emission from a petrol vehicle comprising means for determining the charging energy input to the battery of the EV; means for determining the distance run by the EY; a first data base storage means tor CO2 emission data pertainmg to a predetermined class of a petrol vehicle; a second data base storage means tor CO2 emission data at the electric power generation source pertaining to a predetermined class of an EV; an electronic controller for assessing the difference between the CO2 emission for the EV at any distance travelled and the CO2 emission for the petrol vehicle for the same distance travelled, and thus furnishing the amount of CO2 reduction; a display unit for continuously displaying the said amount of C02 reduction as the EV travels.
2. A device as claimed in Claim 1 wherein the means for determining the charging energy input to the battery of the EY consist of means for aggregating the products of charger voltage, the charging current and the incremental time during charging which include a current sensing circuit for detecting the beginning and end of a charging event.
3.A device as claimed in Claim 1 or Claim 2 wherein the means for detennining the distance run by the vehicle, consist of an odometer.
4. A device as claimed in any one of the preceding Claims wherein the lixst and second storage means contain, respectively, prerecorded standard data of the quantum of CO2 emissions in the case of a specific petrol vehicle and a specific EY.
5. A device as claimed in any one of the preceding Claims wherein the electronic controller incorporates electronic programmable computing means.

6. A de\dce as claimed in any one of the preceding Claims wherein the display \mit includes an electionic device tot displaying chaxacteis OT graphics, the said display unit being driven directly OT through an external circuit by the Controller
7. A device as claimed in any one of the preceding Claims wherein the current sensor measures the value of AC or DC current by giving a voltage/digital output proportionaL to the current.
8. A device for determining the reduced CO2 emission from an EV as
against CO2 emission from a petrol vehicle substantially as herein
described and illustrated with reference to the accompanying drawings.