Surging Charging System

[Ludes]

Wondering if anyone has run into this issue I'm experiencing. My charging system voltage surges when at idle and at low rpm driving. Cant recall how much its changing but at night you can see all the lights get brighter and dimmer. Both alt and reg are fairly new maby 500 miles on them. Alt was a Napa replacement unit and reg is Mopar Perf restoration unit.
Have I got a bad reg? I don't have another to swap in.
Has anyone tried the M/P race unit (advertised as constant 13.5v) on the street?
Thanks everyone

 

[91r/t]

Make sure your regulator is grounded very well. Also make sure your charging voltage (signal) coming from the bulkhead to the regulator is the same as the voltage (signal) at the alt and there isn't a voltage drop somewhere across that circuit. Usually the connector at the bulkhead can get grimy and dirty and cause it to surge or overcharge. My guess is a crappy ground on the unit itself that is causing the surging as the overcharging is usually more constant. My 68 Runner with the newer style 70 and up regulator and my Charger with the older regulator style both had surging issues. Runner ended up being a ground issue and the Charger ended up being the wire that gives a voltage signal to the regulator to control amount of charge the alt puts out. Learned alot about that circuit when messing with them both and the biggest thing was a great ground and a good signal from battery to regulator through the wiring on the bulkhead.

 

[493 Mike]

I used a electronic replacement for the mechanical on my 65 Coronet and it was surging also. I found a newer style electronic (new old aftermarket stock from my stash) and a rebuilt ( by me years ago) two wire square back alternator and that cured the surging. So the new replacement regulator caused my trouble.
Mike

 

[Ranger16]

I put a NAPA alternator in my car a couple of years ago. It lasted a month. When they gave me a replacement, it had a ding in the pulley that looked like it had been dropped and landed on the pulley. I got a refund and went elseware.

 

[Ludes]

Thanks for all the help folks!!