I have been told the VR is in the alternator (which I believe), or possibly in the ECU. Which is it?
After being on the battery tender I leave the garage showing 14+ volts and after a few miles it starts dropping to the 13+ range.
I have read here that 13.5 is within specs, but it worries me by fluctuating. I have a new starter and have checked as many connections. as possible. Do I need a new alternator or a rebuild by a pro... or is there something else I should test?
thanks for any suggestions

 

This post has some good info.

https://www.corvetteforum.com/forums...-2006-vet.html

 

Your car is operating normally from what you describe. As the battery charges from initial startup the output voltage of the alternator will drop a few volts. It will also drop when the cooling fans kick in.
So long as it is above 13V you are good.

Another item, the volt gauge on the dash is not 100% accurate. Put a good DMM across the battery terminals to verify the charging voltage.

Gary

 

thanks, I do appreciate the input. I'm just confused because I was under the impression that when a regulator is "set" it is supposed to hold that number. Until the starter failure I never notice the gauge drop below 14+ volts. Now with the new starter I seem to be having the same issue. BTW the OEM starter was toasted.

thanks again for any thoughts. I may go ahead and throw a new alternator on it because this one is 105,000 miles used.

 

VR is in the alternator, but ECM is controlling the VR.

Hence black part, and the brushing basket is part of the VR as well.

Attachment 48332766

 

I remember seeing a video a while ago about how to clean the alternator which may help with low voltage

 

A couple of thoughts ...

1. If you really did see a change in the car's operating voltage when the starter was changed - it might not be a bad idea to clean all the terminals where they attach to the starter. The alternator output basically goes (indirectly) to the starter terminal, and then back to the battery. If the terminals / connectors were not nice and clean - there could be internal resistance at that connection. (Another way to check would be to look for voltage drop between the alternator output terminal and the battery pos terminal with the car running, and a decent load on the electrical system (say headlights, blower fan and rear defroster). A tenth of a volt drop is fine - but not much above that.

2. Most modern alternators (really voltage regulators) have some degree of temp compensation in them. The alternator output voltage will be higher when cold than after being fully warmed up. You should be seeing at least 13.5 V at the alternator output terminal when the car is fully warmed up and has been running for a while, and under at least some electrical load.

3. It might not be a bad idea to get a can of spray contact cleaner and spray out the connections at the voltage regulator portion of the alternator. It also wouldn't hurt to take the alternator output cable off and clean those contact surfaces. AND ... pull the battery cables and clean both the battery terminals and the cables - a little corrosion there will cause LOTS of issues.