A method of monitoring an electrical storage system for a vehicle having a power source (40, 90) and a load, the method comprising: providing an electrical storage element (95, 100) defining a total storage capacity and having a state of charge cooperatively defining a total stored charge of the electrical storage element; determining a total stored charge value representative of the total stored charge of the electrical storage element; determining a run-time of a load based on the total stored charge value; varying the total stored charge value by charging the electrical storage element from the power source via an electrical charge or discharging the electrical storage element to the load via an electrical discharge; updating the total stored charge value after varying the total stored charge based on a measured quantity of at least one of the electrical charge and the electrical discharge; updating the run-time of the load based on the updated total stored charge value; determining an average voltage of the electrical storage element over a first predetermined time; determining a voltage change of the electrical storage element over a second predetermined time; verifying the runtime of the load based on at least one of the average voltage and the voltage change; comparing the voltage change of the electrical storage element to a first threshold; determining a first predictive total stored charge value representative of the total stored charge of the electrical storage element based on the comparison of the voltage change to the first threshold; comparing the average voltage to a second threshold; determining a second predictive total stored charge value of the total stored charge of the electrical storage element based on the comparisons of the voltage average to the second threshold; and updating the total stored charge value based on one of the first predictive total stored charge value and the second predictive total stored charge value in response to one of the voltage change and the voltage average exceeding the respective first and second thresholds. providing an electrical storage element (95, 100) defining a total storage capacity and having a state of charge cooperatively defining a total stored charge of the electrical storage element; determining a total stored charge value representative of the total stored charge of the electrical storage element; determining a run-time of a load based on the total stored charge value; varying the total stored charge value by charging the electrical storage element from the power source via an electrical charge or discharging the electrical storage element to the load via an electrical discharge; updating the total stored charge value after varying the total stored charge based on a measured quantity of at least one of the electrical charge and the electrical discharge; updating the run-time of the load based on the updated total stored charge value; determining an average voltage of the electrical storage element over a first predetermined time; determining a voltage change of the electrical storage element over a second predetermined time; verifying the runtime of the load based on at least one of the average voltage and the voltage change; comparing the voltage change of the electrical storage element to a first threshold; determining a first predictive total stored charge value representative of the total stored charge of the electrical storage element based on the comparison of the voltage change to the first threshold; comparing the average voltage to a second threshold; determining a second predictive total stored charge value of the total stored charge of the electrical storage element based on the comparisons of the voltage average to the second threshold; and updating the total stored charge value based on one of the first predictive total stored charge value and the second predictive total stored charge value in response to one of the voltage change and the voltage average exceeding the respective first and second thresholds.