Are these voltmeter readings good?

[huntingdog]

Hey. I have a new to me 1993 ST1100 with the original 28A alternator in it. Having read all the 28A failiures I put on a digital voltmeter connected directly to the battery and switch it on/off using a switch, to monitor whats happening.
Voltmeter shows this at running rpm, lets say above 3k.
No lights: 14.3V
Parking lights on: 14.4V
Low beam on: 14.6V
High beam on: 14.9V
Is everything working as it should? I thought that adding electrical load the volts should go down, in my case they are going up? I have no electrical accesories mounted with the exeption of a phone mount + charger, which I rarely ever use, just have it as a backup.

 

[Larry Fine]

Sounds like the voltage regulator compensating.

 

[dwalby]

there's no real theory of operation description for the alternator, but if your readings are at the battery terminals the figures you show aren't surprising. What the alternator will attempt to do is keep the voltage constant at the load side of the ignition switch, or something similar. As the current load increases, the voltage drop between the battery and the load side of the ignition switch will increase (V=I*R), so the alternator raises the battery voltage to compensate for that voltage drop.

 

[kiltman]

On my 1990 I had a similar set-up with my volt meter as you have, however my readings were slightly higher. No matter, it’s when you start to see it under 14V, then I would start to get concerned on the longevity of the system.
Continue to monitor three connectors, those being 1) a red connector between the three yellow wires coming from the alternator to the Voltage regulator/rectifier 2) the white connector to the voltage regulator/rectifier and 3) the red connector to the main relay. Any or all of these may have heat issues and either the connector will melt or the wire will be compromised. Periodically check the alternator for any oil residue as the silicone that is around the wires coming out of the alternator may break down causing the unit to leak oil and thus losing the cooling capacity which will lead to failure of the alternator.

 

[Upt' North]

It's what I would expect to see and is already expertly explained by those above.
Ride.
Upt'North.

 

[huntingdog]

Great info guys. Thanks!