Automobile batteries with inherent immobilizers

An immobilizer for an automotive battery electrically connected between a battery post and a set of cell plates the battery for powering a starter motor and various other automotive loads, comprising:

• a battery voltage input for electrical connection to the set of cell plates;
• an ignition switch input for electrical connection to the battery post;
• a resistive path between the battery voltage input and the ignition switch input to permit current flow between the set of cell plates and the battery post in an amount greater than zero but less than that typically required to power the starter motor;
• a controller;
• a detector circuit to detect an operation of the starter motor attempting to load the battery voltage input;
• and
• a processor connected to open the switch in response to the detection by the detector circuit;
• and
• a switch in parallel with the resistive path to switch the battery voltage input in connection with the ignition switch input, wherein the switch remains closed until opened in response to control signals from the controller.

A method of immobilizing an automobile battery having a set of battery cell plates and a corresponding battery post, the automobile battery for use in an automobile having a security entry device, comprising the steps of:

• detecting a voltage at the cell plates;
• analyzing the voltage to determine if a corresponding current is being drawn to a generally resistive load or a to a generally reactive load based on its change over time;
• detecting whether the security entry device has been engaged;
• and,
• if the current is being drawn to a generally resistive load, permitting a current to pass to the resistive load, and
• if the current is being drawn to a generally reactive load, restricting the current from passing to the reactive load unless the entry device has been detected as engaged.