1. A controller (110) to determine battery drain in a vehicle, said controller
(110) adapted to:
detect engine OFF condition (104), characterized by
measure and compare voltage discharge rate of said battery (102)
with a threshold rate;
while said discharge rate exceeds said threshold rate,
compare at least one parameter with at least one reference map (108) stored in a memory element (106), and determine an incident of battery drain based on said comparison.
2. The controller (110) as claimed in claim 1, wherein said at least one parameter is selected from a group comprising current, voltage and power.
3. The controller (110) as claimed in claim 1, wherein said at least one reference map (108) comprises discharge pattern of said battery (102) with reference to said at least one parameter for at least one electrical load (114).
4. The controller (110) as claimed in claim 3, wherein said at least one electrical load (114) comprises a set of headlamps, a set of taillights, a set of blinkers, a set of fog lamps, a set of wipers, an infotainment unit, an ignition system, an air-conditioner, a set of power windows, a blower, a socket, a horn, sensors, a radio, a security system and other accessories.
5. The controller (110) as claimed in claim 1, wherein said incident is reported to user through an alert signal (112), said alert signal (112) is triggered on any one of a mobile phone through a telecommunication unit of said vehicle, and a buzzer in said vehicle.

6. A method for determining battery drain in a vehicle, said method
comprising the steps of:
measuring discharge rate of at least one battery (102) during engine
OFF condition (104), characterized by
while said discharge rate exceeds said threshold rate,
comparing at least one parameter with at least one reference
map (108) stored in a controller (110), and
determining an incident of battery drain based on said
comparison.
7. The method as claimed in claim 6, wherein said at least one parameter is selected from a group comprising current, voltage and power.
8. The method as claimed in claim 6, wherein said at least one reference map (108) comprises discharge pattern of said battery (102) with reference to said at least one parameter for at least one electrical load (114).
9. The method as claimed in claim 6, wherein said at least one electrical load (114) comprises a set of headlamps, a set of taillights, a set of blinkers, a set of fog lamps, a set of wipers, an infotainment unit, an ignition system, an air-conditioner, a set of power windows, a blower, a socket, a horn, sensors, a radio, a security system and other accessories.
10. The method as claimed in claim 6, wherein said incident is reported to user through an alert signal (112), said alert signal (112) is triggered on any one of a mobile phone through a telecommunication unit of said vehicle, and a buzzer in said vehicle.