VRR voltage ST1100 28amp

[DeanR]

Recently had a problem with low voltage while underway (12 and below). Made it home 400 miles after cleaning and reconnecting the melty red connector, burnt white connector at the red wire, and buying a new 'just in case' battery to have on hand. Even unplugged the headlights. Have since removed the red connector and connected the three yellow wires directly to each other. The alternator seems to test ok. The 40 amper will go in one of these days.

I'm now getting between 14.85 and 15.1 volts while underway (using multiple VRR's) which is about the same as it has always been. A change is that now the voltage barely drops while at idle. Remains at around 14.8 (again, using multiple VRR's) whereas it used to sit at about 13. What would keep the voltage high at idle?

Also, where is the alternator ground?
The VRR's will be available after I get things sorted out, if anybody needs one.

 

[ST1100Y]

What would keep the voltage high at idle?

AFAIK is the alternator output voltage limited/regulated due voltage applied to the exciter winding by the VRR (BL & W cable), so I suspect lack of/low voltage there. Normal values at battery terminals would be ~12,6V at idle, a max of ~15V @ 5000rpm.

Also, where is the alternator ground?

It isn't, ground is provided by the VRR. Had an alt shorting to ground on the refurbed '94 ST, causing total power loss (even with charged batt), until I disconnected the red connector. Resistance values on alternator: yellow/yellow: 3x ~0,4Ohm (infinite to ground); white/black: ~0,4Ohm (infinite to ground). Have you measured the VRR? Yellow/Red-White: 3x 7,5KOhm, White/Red-White: 60KOhm, White/Yellow: 3x 28KOhm (all others: infinite)