Long lived dual battery with automatic latching switch
First Claim
1. An apparatus for supplying electrical power to a system comprising:
- an on-off switch, the on-off switch supplying power from a power supply terminal to a system power terminal in a first state and preventing supply of power from the power supply terminal to the system power terminal in a second state;
a first power supply providing power to the power supply terminal;
a second power supply;
a triggerable switch having a first terminal connected to the power supply terminal, a second terminal connected to the second power supply and a trigger input, the trigger input, when activated causing the first and second terminals to be connected through a lower impedance;
a comparator having an output for indicating a low power condition when a voltage level of the first power supply is below a predetermined reference at a time before the on-off switch supplies power form the power supply terminal to the system power terminal in the first state of the on-off switch; and
a trigger coupled to the trigger input of the triggerable switch and the output of the comparator, the trigger being enabled by engagement of the first state of the on-off switch, the trigger having an output activating the trigger input of the triggerable switch when the comparator output indicates the low power condition.
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Accused Products
Abstract
A latching automatic dual battery switch employs a first comparator to determine that a condition requiring engagement of a secondary battery exists. For example, a primary battery voltage is below a predetermined threshold, current drawn from the primary battery exceeds a predetermined threshold or ambient temperature is below a predetermined threshold. Engagement of an ignition switch is detected and used to clock the output of the comparator to a trigger circuit. The trigger circuit activates the triggerable switch on the leading edge of a signal generated by the detector circuit to connect a secondary battery or power source in parallel with the primary power source. The trigger circuit is leading edge activated so that conditions immediately prior to engagement of the ignition switch determine if the secondary battery is engaged. This avoids engaging the secondary battery as a result of a load surge dragging down the voltage after activation of an ignition switch. In addition, when the ignition switch is released, a timing circuit is engaged to limit the additional time during which the secondary battery is switched in the circuit. The automatic engagement of the secondary battery eliminates the need for manually switching to an emergency backup and manually disengaging the emergency backup after a vehicle is started.
102 Citations
25 Claims
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1. An apparatus for supplying electrical power to a system comprising:
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an on-off switch, the on-off switch supplying power from a power supply terminal to a system power terminal in a first state and preventing supply of power from the power supply terminal to the system power terminal in a second state; a first power supply providing power to the power supply terminal; a second power supply; a triggerable switch having a first terminal connected to the power supply terminal, a second terminal connected to the second power supply and a trigger input, the trigger input, when activated causing the first and second terminals to be connected through a lower impedance; a comparator having an output for indicating a low power condition when a voltage level of the first power supply is below a predetermined reference at a time before the on-off switch supplies power form the power supply terminal to the system power terminal in the first state of the on-off switch; and a trigger coupled to the trigger input of the triggerable switch and the output of the comparator, the trigger being enabled by engagement of the first state of the on-off switch, the trigger having an output activating the trigger input of the triggerable switch when the comparator output indicates the low power condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for supplying electrical power to a system comprising:
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an on-off switch, the on-off switch supplying power from a power supply terminal to a system power terminal in a first state and preventing supply of power from the power supply terminal to the system power terminal in a second state; a fist power supply providing power to the power supply terminal; a second power supply; a triggerable switch having a first terminal connected to the power supply terminal, a second terminal connected to the second power supply and a trigger input, the trigger input, when activated causing the first and second terminals to be connected through a low impedance; a comparator disposed to compare a parameter indicative of the power level of the first power supply to a predetermined reference condition, the comparator having an output for indicating when the parameter is outside a predetermined reference condition; and a trigger coupled to the trigger input of the triggerable switch and the output of the comparator, the trigger being enabled by engagement of the first state of the on-off switch, the trigger having an output activating the trigger input of the triggerable switch when the comparator output indicates the parameter is outside the predetermined reference condition. - View Dependent Claims (16, 17, 18, 19)
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20. A method of supplying electrical power to a system comprising:
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supplying power form a power supply terminal to a system power terminal through an on-off switch in a first state and preventing supply of power from the power supply terminal to the system power terminal in a second state; providing power to the power supply terminal through a first power supply; connecting the first and second terminals through a triggerable switch, the triggerable switch having a first terminal connected to the power supply terminal, a second terminal connected to a second power supply and a trigger input, the trigger input causing the first and second terminals to be connected when activated; indicating a low power condition form an output of a comparator when a voltage level of the first power supply is below a predetermined reference at a time before the on-off switch supplies power from the power supply terminal to the system power terminal in the first state of the on-off switch; and enabling a trigger, which is coupled to the on-off switch, the trigger input of the triggerable switch, and the output of the comparator, by engagement of the first state of the on-off switch, the trigger having an output activating the trigger input of the triggerable switch when the comparator output indicates the low power condition. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification