US 5,296,997 A · System for protecting a battery

Abstract

A vehicle storage battery protection system that senses a drop in battery voltage to a level at which the battery still retains sufficient power to start the vehicle. If the sensed voltage remains at or below this level for a time greater than the time normally required to start the vehicle, the battery is disconnected from the load and a hysteresis signal is provided to prevent a reconnection as the battery voltage begins to rise after the load has been disconnected. The load is automatically reconnected to the battery upon operation of the ignition switch to restart the vehicle. A reset circuit provides a small test voltage to the disconnected load, and senses a voltage drop caused by operation of the ignition switch to start the vehicle. This sensed voltage drop is detected and causes a main switch to reconnect the battery to the loads.

Claims12

Dependent claims

For use in conjunction with a vehicle having a battery, an ignition system, and at least one electrically powered load connected to the battery, a device adapted to electrically disconnect the battery from the at least one load whenever the battery energy falls below a predetermined value, comprising:

a normally closed main switch connected in series between the battery and the load;
means for sensing a battery characteristic indicative of battery drain and for generating an output signal whenever an energy capacity of said battery falls below a predetermined value;
timing means responsive to said sensing means output signal for generating a timing output signal a delay interval after said sensing means output signal;
means responsive to said timing means output signal for opening said switch;
means for generating a signal when the engine is running;
and
means, including a pulse pump circuit, for inhibiting generation of said timing output signal responsive to said engine running signal.

4 more elements

For use in conjunction with a vehicle having a battery, an ignition system, and at least one electrically powered load connected to the battery, a device adapted to electrically disconnect the battery from the at least one load when the vehicle is not in operation and the battery energy falls below a predetermined value, comprising:

a normally closed switch connected in series between the battery and at least one load;
means for sensing a battery characteristic indicative of battery drain and for generating an output signal whenever an energy capacity of said battery falls below a predetermined value;
timing means responsive to said sensing means output signal for generating a timing output signal a delay interval after said sensing means output signal;
and
means responsive to said timing means output signal for opening said switch;
wherein said sensing means comprises a voltage comparison circuit operable to substantially immediately activate said timing means whenever the energy capacity of the battery falls below a predetermined threshold, without regard to the voltage level or the value of the at least one electrically powered load.

3 more elements

Dependencies are inferred from the claim text.

System for protecting a battery

Life of this patent

System for protecting a battery

Life of this patent

Abstract

Claims12