A power supply system includes a first connector, a second connector, a first circuit for detecting a magnitude of a current drawn from an energy source by the power supply system and providing a related output related, and a second circuit for adjusting an output voltage supplied to the second connector based on output of the first circuit. The output voltage supplied to the second connector is at a first value when the output of the first circuit is below a first threshold. Further, the output voltage supplied to the second connector is at a second value, greater than said first value, when the output of the first circuit is above a second threshold. The output voltage supplied to the second connector is at a third value, between said first and second values, when the output of the first circuit is between the first and second thresholds.