An integrated energy storage unit includes a container and a battery housed within the container. The battery includes a positive battery terminal, a negative battery terminal, and a battery electrolyte. A capacitor is housed within the container, separate from the battery. The capacitor includes a positive capacitor terminal, a negative capacitor terminal, and a capacitor electrolyte. A plurality of connectors electrically couple the battery and the capacitor in parallel. A positive lead is electrically coupled to the positive battery terminal and the positive capacitor terminal. The positive lead extends from the container. A negative lead is electrically coupled to the negative battery terminal and the negative capacitor terminal. The negative lead extends from the container.