If I have a source putting out a constant DC voltage and amps and I want to use it to power say my laptop(although likely not my laptop). Let's say the constant power is 16V DC and 5 amps, and my laptop's power cord is say it converts my AC wall wattage to 16V DC @ 3.6 amps... what would I need to put in my power source so that unused Volts an Amps is converted to heat or something?