very good DCDC converter.

The efficiency seems very good; in continuous operation with 2 empty units and approximately 8W input power the device was no little warm. The output voltage is virtually independent of the load. Sounds like something the whistle of coils are not to hear. At idle about 18mA current consumption. Undervoltage cutoff at about 8V; which should lead in the car now and then breaks at the start pulses by engine starting, especially in winter.
In 2 of the connectors are shorted D + and D-, so most devices will accept these jacks as charger. The two other sockets have placement stations for 0805er resistors, so that Apple devices can be made happy. The resistors are not included. The module is built very sturdy and compact!