Monday, December 7, 2015
Car Battery Saver
Car Battery Saver - Prevents the complete discharge of the battery when the door is left open accidentally
I recently forgot to close the door of my car after parking in the garage and I found the battery completely exhausted after the week-end, when I tried to start the engine on Monday morning. This inconvenience prompted me to design a simple circuit, capable of switching-off automatically after a few minutes the inside courtesy lamp, the real culprit for the damage.
Car Battery Saver circuit diagramParts:
R1______________10M 1/4W Resistor
R2______________10K 1/4W Resistor
C1______________47µF 25V Electrolytic Capacitor
IC1____________7555 or TS555CN CMos Timer IC
D1___________1N4148 75V 150mA Diode
Q1____________BD681 100V 4A NPN Darlington Transistor
LP1___________Existing Lamp Bulb, usually 12V 5W
SW1____________SPST Existing Door-Switch
SW2____________SPST Existing Bypass Switch
Circuit operation:
At the point when the entryway is opened, SW1 shuts, the circuit is fueled and the light is on. C1 begins charging gradually through R1 and when a voltage of 2/3 the supply is come to at pins #2 and #6 of IC1, the inward comparator changes the condition of the flip-slump, the voltage at pin #3 tumbles to zero and the light will switch-off. The light will stay in the off state as the entryway is shut and will enlighten just when the entryway will be opened once more. The last result is a three-terminal gadget in which two terminals are utilized to unite the circuit in arrangement to the light and the current entryway switch. The third terminal is associated with the 12V positive supply.
Notes:
With the qualities indicated for R1 and C1, the light will keep focused around 9 minutes and 30 seconds.
The time deferral can be changed by differing R1 and/or C1 values.
The circuit can be circumvent by the normally existing switch that permits the inside light to enlighten ceaselessly, notwithstanding when the entryway is shut: this association is appeared in dabbed lines.
Current drawing when the circuit is off: 150µA
I recently forgot to close the door of my car after parking in the garage and I found the battery completely exhausted after the week-end, when I tried to start the engine on Monday morning. This inconvenience prompted me to design a simple circuit, capable of switching-off automatically after a few minutes the inside courtesy lamp, the real culprit for the damage.
Car Battery Saver circuit diagramParts:
R1______________10M 1/4W Resistor
R2______________10K 1/4W Resistor
C1______________47µF 25V Electrolytic Capacitor
IC1____________7555 or TS555CN CMos Timer IC
D1___________1N4148 75V 150mA Diode
Q1____________BD681 100V 4A NPN Darlington Transistor
LP1___________Existing Lamp Bulb, usually 12V 5W
SW1____________SPST Existing Door-Switch
SW2____________SPST Existing Bypass Switch
Circuit operation:
At the point when the entryway is opened, SW1 shuts, the circuit is fueled and the light is on. C1 begins charging gradually through R1 and when a voltage of 2/3 the supply is come to at pins #2 and #6 of IC1, the inward comparator changes the condition of the flip-slump, the voltage at pin #3 tumbles to zero and the light will switch-off. The light will stay in the off state as the entryway is shut and will enlighten just when the entryway will be opened once more. The last result is a three-terminal gadget in which two terminals are utilized to unite the circuit in arrangement to the light and the current entryway switch. The third terminal is associated with the 12V positive supply.
Notes:
With the qualities indicated for R1 and C1, the light will keep focused around 9 minutes and 30 seconds.
The time deferral can be changed by differing R1 and/or C1 values.
The circuit can be circumvent by the normally existing switch that permits the inside light to enlighten ceaselessly, notwithstanding when the entryway is shut: this association is appeared in dabbed lines.
Current drawing when the circuit is off: 150µA
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