I did the relay mod and it seemed to stabilize my charge at 14.5 volts while cruising, but I did notice at idle in gear about 750 rpm my volt meter is bouncing between 14 and just under 16 volts.
....maybe a lose wire that jiggles when your motor is at idle and thumping along......and then when motor is at a constant acceleration it isn't "idle jiggling" the lose wire???