Question Can I test DC to DC converter without load ?

[hw_user]

I just got a DC-to-DC bulk converter step-down module. I want to use it to step down my surplus 16.5 Volt laptop power supply to 12V. I connected the 16.5V laptop power supply to the input of the module and a voltmeter to the output. But I saw the voltage on the meter going between 10v and 3v ( i.e the reading went from 10V 9V --- 3V and back up 4v----9v 10v). The module has a potentiometer for output adjustment. But why is the output varying? I was wondering if I my method of testing is correct. Do I need a load ? or does the bulb converter work with my input power brick?

 

[punkncat]

If you connect to the original power brick are you seeing the variation with it as well, or only after using the converter?

Do you have another brick you would feel secure trying in order to see if the issue lies with the 'step down' module?

Of course, this also should consider the source. Where are you and what source output is being used and is it mains or a generator, solar panel, or other type?

 

[hw_user]

I used 12V from an ATX power supply as input and the no-load output gave me a stable 4.5V. Perhaps the DC output is not the same between an ATX PS and my laptop adaptor. The bulk converter has two adjustment ports (CV, constant Voltage, and CC, constant current). With the ATX power supply as 12V input, I adjusted the voltage control potentiometer (CV). There was no change to the output voltage. The question remains do I need a load to adjust the output voltage? If yes, How can I make a DC load?