Voltage at idle too low, and too high above idle

[8v-of-fury]

When idling, the engine is slow enough that the DC meter (is this amps or voltage btw?) is in discharge, and my plug-in 12v power socket shows like mid 11v.

However at cruise I see like 15.2v! WHOA. No wonder the lights and fan really pick up when it gets up off idle! LOL Obviously that wild of a swing is no good right? Alt? or voltage reg?

 

[Mikes5thAve]

That's telltale sign of bad voltage regulator. They're cheap and easy to change so I always do that first.
Make sure the connections at the battery and alternator are tight first.

 

[8v-of-fury]

Yeah, looks to be up on the passenger firewall. I'll get one ordered up.
Battery connections are good, however I will check the alternator as well.

 

[Aspen500]

It generally causes a no charge condition if the regulator has a poor ground but, make sure the regulator is grounded well. They ground through the case at the mounting screws. A good idea is to also add a ground wire under one of the screws and run it to the engine or other good grounding point, just to be sure.