Bulkhead bypass vs ammeter bypass

remytherat said

Thanks for the pointer, I have a magnum harness kicking around from my 5.9 swap.

So you’re basically running a zener that activates the shunt wire when the alt out is 0.7V greater than bat+?

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Not a zener. I forgot if silicon or germanium. The diode is forward-biased, in both directions (2 in parallel). It always conducts forward, just very little current until >0.5 V drop, then current increases exponentially with voltage drop. I tested that keeps the dash ammeter from pegging, perhaps tops out ~3/4 scale with a squareback alternator on full-field. Fine for me since I just care to see its charging after starting the car.

I recall ~200A rating (depends on heat-sink). Bolt terminals. Actually dual diodes in the package on an aluminum base. I cut in two, flipped one around, and bolted together to realize parallel diodes. Posted PN in the past w/ photos. You'll have to search. Few people here could understand or follow. One guy bulked up my post arguing (with an engineer) about current and voltage that he didn't understand.