Got my hands on a cheap "Green Galaxy" (also known by other names) DC-DC converters" spec'dInput voltage range:
30V - 60VOutput:
to use on a converter motorcycle and did some tests. The purpose was to see how much power could I take from it and to change its output voltage to around 13.8V to charge a small on-board 12V battery. I ended up reverse-engineering the schematics to see exactly what it does. So here's the study result:Output impedance:
~ 0.035 OhmOutput voltage, no load:
Tested up to 8A output for a few seconds; voltage falls linearly according to output impedance.
Almost complete schematics (sorry for old-school hand drawing
Then I soldered a 5K6 5% in parallel with the 1K2 bottom output divider resistor to get the output voltage up to around 13.8V:
Tested the converter @ 23ÂºC ambient temperature for one hour running at 70W output load, and the box gets finger burning hot (over 60ÂºC), so I won't recommend using it continuously for higher power than this without "active" cooling.Update:
Typical output ripple:
I haven't tried yet, but it seems that these converters, being "current mode" converters, can have their outputs connected in parallel and will share the load.