This example shows how a DC-DC converter can be used to maintain a constant load voltage when drawing power from an ultracapacitor. Initially the converter supplies power to the load, and as it does so, the capacitor voltage drops. The protection circuit disconnects the load when the capacitor voltage drops below a threshold of 4V. At 10 seconds the generator is turned on, and power is supplied to both the load and to the capacitor to recharge it.
The plot below shows voltage supplied to a resistive load from an DC-DC converter and a generator. The DC-DC converter supplies power to the load. A low charge protection circuit disconnects the load when the ultracapacitor voltage drops below 4V. At 10 seconds the generator turns on, supplying power to the load and charging the ultracapacitor.