Off-grid battery system for radio site

[Sunking]

Downside is a buck can't change output polarity (I-O not isolated).

Bruce they make Isolated Converters so you can change which polarity is bonded to ground. It is a good point to bring up.

[sdold]

Can a buck converter handle widely varying loads? In theory, the 12V load can go from a couple of amps to 200 amps if everybody managed to key up at the same time. More likely is about half of the stations might be keyed occasionally.

[bcroe]

Can a buck converter handle widely varying loads? In theory, the 12V load
can go from a couple of amps to 200 amps if everybody managed to key up at the same
time. More likely is about half of the stations might be keyed occasionally.

Biggest buck I have done was 30A for a wide range 1KW power supply. The basic "buck"
doesn't have a limit. Usually on that scale several smaller ones would be put in parallel on
a phased basis, so that the overall ripple would be much reduced (like a 4 cylinder engine
instead of one really big one). The buck has a problem with increase ripple if the output
current drops to something like 5% of its rating, not really fatal. Current transients aren't
handled as easily. But they really do well over varying voltages. Bruce Roe