Protective monitoring circuit for a vehicle battery

Claim 2

A protective monitor for a vehicle battery wherein the vehicle has an electrically actuated component additional to electrical components required for driving the vehicle comprising: an indicator for warning the operator of said vehicle of an undesirably low battery voltage; a voltage sensing means coupled to said battery; a short term timer coupled between said voltage-sensing means and said indicator for activating said indicator after a first fixed-time interval has elapsed following a decrease of battery voltage to a predetermined level; a long term timer coupled between said short term timer and said electrically actuated additional component of said vehicle and operative to deactivate said additional component of said vehicle after a second fixed-time interval has elapsed following activation of said indicator, said second time interval being greater than said first time interval, said components for driving said vehicle being unaffected by said operation of said longterm timer; and a filter circuit having resistive and capacitive elements coupled to said voltage sensing means, said filter circuit resisting rapid voltage changes at said voltage sensing means whereby said voltage sensing means does not respond to transient voltage decreases.

Claim 3

A monitoring circuit for a vehicle battery wherein the vehicle has an electrically actuated component additional to electrical components required for driving the vehicle comprising: an electrically operated indicator device connected across the terminals of said battery; a first switching means connected in series with said indicator device and having a conductive and a nonconductive condition for controlling said indicator; an electrically actuated control element for said additional component of said vehicle; a second switching means connected in series with said vehicle component control element and having a conductive and a nonconductive condition; a resistor connected across said battery terminals; voltage sensing means connected across said battery terminals and having a conducting and a nonconducting condition as determined by the voltage applied to a control terminal thereof, said control terminal being coupled to said resistor whereby said voltage sensing means is switched from one condition to another when the voltage across said resistor drops to a predetermined level, said voltage sensing means having an output terminal; a short term timing circuit having an input connected to said voltage sensing means output terminal for actuation by said change of condition thereof and having an output coupled to said first switching device for operating said switching device following a first predetermined period after switching of said voltage sensing means whereby said indicator is actuated after said first period; a long term timing circuit actuated in response to actuation of said indicator and having an output coupled to said second switching device for operating said second switching device following a second predetermined time period after actuation of said indicator whereby said additional component of said vehicle is inactivated if the reduced battery voltage condition is not corrected within said second predetermined time period; said long term timing circuit having a resistor and capacitor coupled to said indicator device whereby said capacitor commences to charge upon energization of said indicator, said resistor and capacitor having a time constant which determines said second predetermined time period, and having a unijunction transistor having a base terminal controlling said second switching device and having an emitter coupled to said capacitor whereby said transistor produces an output signal at said base terminal after said second predetermined time period; and said monitoring circuit further comprising a pulser actuated by said voltage sensing means and having an output delivering a series of accurately timed electrical pulses, said output being coupled to said base of said unijunction transistor.

Claim 4

A monitoring circuit for a vehicle battery wherein the vehicle has an electrically actuated component additional to electrical components required for driving the vehicle comprising: an electrically operated indicator device connected across the terminals of said battery; a first switching means connected in series with said indicator device and having a conductive and a nonconductive condition for controlling said indicator; an electrically actuated control element for said additional component of said vehicle; a second switching means connected in series with said vehicle component control element and having a conductive and a nonconductive condition; a resistor connected across said battery terminals; voltage sensing means connected across said battery terminals and having a conducting and a nonconducting condition as determined by the voltage applied to a control terminal thereof, said control terminal being coupled to said resistor whereby said voltage sensing means is switched from one condition to another when the voltage across said resistor drops to a predetermined level, said voltage sensing means having an output terminal; a short term timing circuit having an input connected to said voltage sensing means output terminal for actuation by said change of condition thereof and having an output coupled to said first switching device for operating said switching device following a first predetermined period after switching of said voltage sensing means whereby said indicator is actuated after said first period; a long term timing circuit actuated in response to actuation of said indicator and having an output coupled to said second switching device for operating said second switching device following a second predetermined time period after actuation of said indicator whereby said additional component of said vehicle is inactivated if the reduced battery voltage condition is not corrected within said second predetermined time period; said long term timing circuit having a resistor and capacitor coupled to said indicator device whereby said capacitor commences to charge upon energization of said indicator, said resistor and capacitor having a time constant which determines said second predetermined time period, and having a unijunction transistor having a base terminal controlling said second switching device and having an emitter coupled to said capacitor whereby said transistor produces an output signal at said base terminal after said second predetermined time period; and said monitoring circuit further comprising a pulser actuated by said voltage sensing means and having an output delivering a series of accurately timed electrical pulses, said output being coupled to said base of said unijunction transistor.