Once UV is reached, the load on the battery must effectively go to zero or damage is still a risk, so low leakage during this condition is critical. Having the ability to notify the system prior to a power outage is also important. Even better would be the ability to provide storage capacity information and a profile of the energy that is being harvested, which would allow a CPU to make intelligent decisions on load usage. For example, based on the current state of the battery and the past information on the energy available from the environment, the system could determine how many more transmissions would be possible in a given time, or it could stretch the duty cycle of data transmission so that the system would continue to run perpetually or bring the battery level back up. The power converters should be as efficient as possible, especially at low power levels. And lastly, some applications may need to support an additional input like USB or a primary cell.