RPM drop and electric fans!

72bluNblu said

That’s a great idea!

But I think the 400 rpm drop is excessive and that should be sorted out first.

Not knowing what fans are on there exactly it’s hard to say, like on my car my contour fans pull less in the low speed that comes on first than what they’re capable of at their high speed, but I would expect the idle rpm drop to be more like half what the OP has. There will be a drop, the alternator is loading the engine more with that amperage draw from the fans, but 400 rpm seems excessive.

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I moved to ECU control and a high/low switch for my Contour fans this year. So basically the computer only knows "fan on" or "fan off" but the speed is selected afterwards. They now can cycle from a stop on high if that's what I wish, have done it during Power Tour and the Dream Cruise and you barely notice. I measured the inrush with the engine off and its 65.2A.

The battery does act somewhat like a capacitor so its proximity will reduce the voltage dips and spikes during transients.

My car has EFI so it will adjust to get the right idle speed but it would take a second or two to find it again. Its not very noticeable.

It would be possible to add a very large capacitor to blunt transient effects IF its only an instantaneous problem.