I have a 68 Chrysler Newport convertible I have done a ton of custom work to. I rebuilt the 383 and radiator, added a fitech fuel injection, a pertronix flame thrower ii electronic ignition and coil, I upgraded to a one wire alternator with about 75 amps. Have a new battery. I just put in a brand new engine bay wiring harness. I bypassed the ballast resister with the new ignition. Newer starter relay and voltage regulator. Added relays to the headlights. Long story short literally almost everything is new. But..........I have one issue that makes me absolutely hate my car. Everytime I think I fix the car it reminds I haven't. So one day the alternator will charge the battery, the next day it won't, the next day it will and so on and so on. I'm gonna lose my mind. My other message board people say oh it's a grounding issue. I have one wire going straight from the alternator to the battery and I have tried grounding the alternator bracket straight to the battery, I've tried grounding the block to the frame. Clearly the alternator works cause I have days it charges. Maybe it's a loose wire but how. The alternator goes straight to the battery and is grounded. What gives? And big middle fingers to every shop in my area. They just charge me and don't fix the issue. I have thrown so much money at this car and I just can't get it reliable. What do I do next to trouble shoot this charging issue?

 

I had a similar problem this summer. As you noted, the alternator needs power before it makes power. Double check there's power (test light) when it's not making volts. The other thing is what I had a problem with and have seen many times when I worked on these things in the dealer is the electrical junction box on the firewall. I took mine apart after disconnecting the battery, sprayed electrical cleaner and scrubbed it down with a toothbrush. Make sure all those contacts are in their right place and not pushed back in the electrical block missing the connection. It worked for me. Good luck!!

 

FYI, Thats not how you fix grounds !!!!! Too much paint between all those fasteners and joints!!!!
Your grounds should all be clean for one....
Grounds>>>> Engine to Body (like behind the passange side cylinder head to the body) and Body to Frame. ( Lower firewall to Frame) and at the rear of the car ( Right hand side near the tailpipe up underneath, Body to Frame)
This should tie it all together for a good solid grounding. Make sure the surfaces are all clean and free of dirt oil, also Dielectric Grease would help if you live in one of those wet and salted areas...

AS for the issue of your charging, Sounds like it is a Voltage Regulator Problem. .And i think your on the rite track with knowing its could be a ground issue...

Good luck and keep us posted.... Cheers

 

I agree with RacerHog on clean grounds. I didn't know how to say it, but yes it needs clean neat wiring to start. Some of the most difficult problems to diagnose and fix are man-made.