A method for operating an ultracapacitor system used in a mining excavator powered by an power source. The method includes detecting whether a power from the power source is present. Next, a voltage level of the ultracapacitor system is measured if the power is not present. The measured voltage level is then compared with a minimum voltage level for the ultracapacitor system. If the measured voltage level is more than the minimum voltage level, auxiliary power is supplied from the ultracapacitor system to operate mining excavator systems. The auxiliary power may be used to power electronic systems and components such as computers, displays, control systems, gas insulated switchgear and lighting systems.