Engine idle speed logic systems and methods

A method comprising:

• determining a state of charge (SOC) of a battery;
• determining a maximum output of an alternator at a current idle speed of an engine;
• determining a load on the alternator;
• and
• initiating an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output,
• wherein determining the SOC of the battery comprises modeling the SOC of the battery, the modeling comprising:
• modeling a decrease of the SOC based on an alternator field duty being greater than or equal to an alternator field duty threshold;
• and
• modeling an increase of the SOC based on the alternator field duty being less than the alternator field duty threshold.

A method, comprising:

• determining a state of charge (SOC) of a battery;
• determining a maximum output of an alternator at a current idle speed of an engine;
• determining a load on the alternator;
• and
• initiating an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output,
• wherein the determining the maximum output of the alternator is based on:
• a targeted alternator output voltage from a charge control system;
• a product of engine speed and an alternator pulley ratio;
• and
• a combination of an alternator excitation current and an alternator field duty.

An idle control system comprising:

• a logic device configured to:
• determine a state of charge (SOC) of a battery,
• determine a maximum output of an alternator at a current idle speed of an engine,
• determine a load on the alternator, and
• initiate an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output,
• wherein:
• the logic device is configured to initiate the increased idle speed based on the determined SOC being below an SOC threshold;
• and
• the logic device is further configured to initiate a decreased idle speed of the engine based on the determined SOC being greater than the SOC threshold,
• wherein the logic device is configured to initiate the decreased idle speed further based on a comparison between a field duty of the alternator and a current demand of an electric cooling fan.

An idle control system, comprising:

• a logic device configured to:
• determine a state of charge (SOC) of a battery,
• determine a maximum output of an alternator at a current idle speed of an engine,
• determine a load on the alternator, and
• initiate an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output,
• wherein the logic device, in determining the SOC of the battery, is configured to model the SOC of the battery, the modeling comprising:
• modeling a decrease of the SOC based on an alternator field duty being greater than or equal to an alternator field duty threshold;
• and
• modeling an increase of the SOC based on the alternator field duty being less than the alternator field duty threshold.

An idle control system, comprising:

• a logic device configured to:
• determine a state of charge (SOC) of a battery,
• determine a maximum output of an alternator at a current idle speed of an engine,
• determine a load on the alternator, and
• initiate an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output,
• wherein the logic device is configured to determine the maximum output of the alternator based on:
• a targeted alternator output voltage from a charge control system;
• a product of engine speed and an alternator pulley ratio;
• and
• a combination of an alternator excitation current and an alternator field duty.

An idle control system, comprising:

• a logic device configured to:
• determine a state of charge (SOC) of a battery,
• determine a maximum output of an alternator at a current idle speed of an engine,
• determine a load on the alternator, and
• initiate an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output,
• wherein the logic device is configured to determine the load on the alternator based on a comparison between an engine coolant temperature and a coolant temperature threshold.