Battery condition monitoring system and method for an engine start up system

A method for monitoring the condition of a battery in a system having an engine and an engine speed sensor, comprising:

• receiving one or more parameter values from an engine start up system, the parameters including data indicating a voltage drop from an initial voltage before the engine starts to an engine recovery steady battery voltage and an engine speed value of the engine from the engine speed sensor;
• determining a battery resistance value through a resistance estimator module by:
• dividing an offset voltage change by a steady-state current change,
• wherein the offset voltage change is determined by the voltage drop from an initial voltage before the engine starts to the engine recovery steady battery voltage,
• wherein the steady-state current change is based in part on the engine speed value and in accordance with a gear ratio associated of the engine, and
• outputting the battery resistance value to calculate the battery condition, and
• based on the battery condition, generating an alert that is associated with the battery.