Thanks for the tip

This alternator appears large enough to be my primary. I've been talking to B&C for a while, trying to get my loads down to allow their 20 amp vac pad alt to do the job. One issue that is not well advertized is that the B&C unit does not put out any significant power at idle. The salesman at the SnF booth basically said zero. I plan to check on this GAMA unit to see if it is similar.
 
Bill,

I have an SD-20 on Bus B, and there is always a low voltage condition at idle up to about 1500 RPM. Once you takeoff though it's fine.
 
Think a bit here.

The main alternator is driven from the flywheel pulley-----apx 10", to a pulley about 3" on the alt itself.

Roughly 3 to 1 overdrive.

The accessory pad is at engine speed, or maybe half I would imagine.

Seems normal for an alternator on the acc drive to be weak at idle.
 
Darned physics, anyway

Yep, I know the vac pad is at 1.3 : 1 . vs the approx 3:1 available using a belt. When I first began dreaming of using the vac pad as primary, I had hoped that the B&C 20 amp alternator windings were designed for the lower rpm. Instead, it is essentially using the belt driven alternator rotor and windings in a new casting and accepting what you get in regards to power. This is a reasonable design for a backup alternator, but hey, I've been called unreasonable before :D
 
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