Generator polarizing question

[Badpuppy]

We won't tell those guys that the battery doesn't "control" anything, although it appears to - it's simply a reservoir. But that's somewhat beside the point.

It's good you have a VM to monitor the battery. Normal resting charge should be near 12.6V and charging voltage should be anything above that, up to 15.5V or so. Above 15.8 the battery hydrates, and becomes damaged. Experience will tell you where to set your 3rd brush for anticipated driving conditions.