A heat pipe includes one or more reservoirs of liquid that are closed at lower temperatures and open at higher temperatures. The opening of the reservoirs at higher temperatures caused by higher power levels dynamically increases the amount of liquid in the heat pipe, which increases performance of the heat pipe at higher power levels. As the heat pipe cools, the liquid condenses and flows back into the reservoirs. As the heat pipe continues to cool, the reservoirs close. The result is a heat pipe that is more efficient at lower power levels and still maintains high efficiency at higher power levels due to the demand-based charging of the liquid based on temperature.