def calculate_engine_start_current(engine_start, start_demand,
    alternator_nominal_voltage, delta_time):
    """
    Calculates the current demand to start the engine [A].

    :param engine_start:
        When the engine starts [-].
    :type engine_start: bool

    :param start_demand:
         Energy required to start engine [kJ].
    :type start_demand: float

    :param alternator_nominal_voltage:
        Alternator nominal voltage [V].
    :type alternator_nominal_voltage: float

    :param delta_time:
        Time step [s].
    :type delta_time: float

    :return:
        Current demand to start the engine [A].
    :rtype: float
    """
    if engine_start:
        den = delta_time * alternator_nominal_voltage
        if den:
            return -start_demand / den * 1000.0
    return 0.0
