Singularity Reactor

An archeotech power sources. One similar to size of reactors normally installed on battleships (that require four of them to be fully powered) produces more or less as much energy as entire battleship squadron needs to work. Which is the best description of how wonderful little things they are.
There are many theories that try to describe how exactly Singularity Reactors produce energy, but which exactly is true? Noone knows. They are extremely rare and the market demand for them is suprisingly small, since only the complete madman would install on his ship something that de facto is a microscopic black hole closed in the small box.