The electrified boatlift is working fine, but it wants 12 volts. That's available if I just suck one tit of the 24 volt trolling motor supply, but I'd rather balance the load -- so I'd like to drop 24DC to 12DC. PWM can do that.
I'm guessing that the ATV winch motor draws 50 amps or less of 12 volts because the 10-gage wires don't get warm and it doesn't seem to be straining any in spite of how it screams. It screams about the same going up or down. Some of y'all may have known women like that. Not me, I'm from Minnesota.
Anyway, my son the silicon peddler came over with a stick of sample MOSFETS rated at 120 amps. They oughtta work. He left with my Milwaukee portable bandsaw, but I'm happy to report that it has returned after doing whatever he did with it. Blade seemed OK and clean enough that I won't bother soaking it in bleach to remove DNA.
I cooked a little circuit to use the MOSFETs, based on a really cheap fluorescent ballast chip from IR. Half bridge driver with bootstrapped topside drive, what's not to like -- particularly since I had samples. They're obsolete, but they work just fine.
The whole circuit, using dinosaur-age thru-hole parts and laid out on a single-layer board by this dinosaur, is about 1-1/2" x 2". I suppose I'll beef up the 50-amp traces with a bit of 14-gage house wire soldered to the traces.
Funny how things work some days. Consider the size and weight of a
600 VA transformer vs this 24VDC to 12VDC converter that will cost me about zip and will be half the size of a deck of smokes just because it turned out that way. The stars and planets were all in alignment on this one.Smoke test in the next coupla days.