Intermittent Voltage Issue

[KDMatt]

Hey guys... so I've been having a weird issue with my '76 ...

A couple of weeks ago I was driving around and all of a sudden the little red 'chg' light on the far right of the voltmeter clicked on (and so did the brake light on the speedo).... it was night, I had my lights on, and my stereo, but nothing else.

No big deal though, I limp home (it starts raining, I flip on the wipers which are HELLA slow at this point), car never dies, go back out the next day, start her up, still get the CHG light with no load whatsoever.

At this point I'm a little suspiscious, so I pop the hood and start digging around... I clean up the connectors off the alternator, I clean up my groundposts and battery terminals, I start it up, same thing... but I'm late for an errand so I drive anway, car's fine.

I park it for 15 minutes, get back in, start her up, CHG light goes away, and the voltmeter is pinned to the right side... (mine's a bit out of calibration, so probably really like 15.5 volts) ... and that's the way she stayed load, or no load, at speed she maintained around 15 volts of power, except for tonight.

It's raining, I flip on my lights, I flip on the wipers, listening to the radio... after 10 minutes of city driving, the CHG light comes on and won't go away after a 20 minute freeway commute of sustained 3k rpm driving. Voltmeter reads a hair above 12 ...

I exit, sit at a stop light, turn off the lights for a second, voltmeter flips up to about 13 ... still keeps the 'chg' light though ... I gun it as I start off again, bury the tach at 5k rpm ... chg light goes away, I shift through, leave it in third at 40 mph for a few extra seconds, then shift to 4th and voila, the voltmeter goes back and sticks it out at about 15 volts (with wipers at full speed and headlights on) for the last mile of my commute.

What the hell is going on?? I've got some very serious gremlins here... alternator was replaced 3 years ago (lifetime warranty) ... voltage regulator was replaced about the same time ... battery was just replaced in the fall and my battery terminals are clean... Wtf?!!

Is my 'new' regulator crapping out?

[Nissanman]

Is my 'new' regulator crapping out?

Short answer, yes:(

It may be that the regulator needs adjustment.

I posted the instructions for that procedure on this site some time ago.

It is the job of the regulator to tell the alternator what to do.

I suggest you have the charging system checked by a competent shop.

It is important to rectify the fault ASAP in order to avoid either a flat battery or worse, an overcharged battery which could explode:dead: