alternator upgrade???
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
alternator upgrade???
Hi guys, I just upgraded my '85 to the CS144 alternator and I don't feel everything is as it should be. I am only getting 13.2-13.3 volts on the dash gauge and 13.7 - 13.8 on 2 different digital voltmeters. My old alternator was 13,8 to 14.2 give or take a few tenths. I had to put 2 alternators on, the first one was DOA out of the box and now this one does not seem to be quite right. I can turn on headlights blower on high and both fans turned on and it stays the same, no difference between idle and higher rpms either. If you have done this swap what were your results?
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I was sure it was okay but it just wasn't what I thought it should be. Got another one, it's putting out 14.3 same type alternator. Now I'm satisfied.
Team Owner
Joined: Sep 2001
Posts: 62,127
Likes: 1,727
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Yeah I'd be alarmed that it wasn't matching what the CS130 had on the dash too, even though the dash is notoriously wrong. I had no issues when I did this though.
Safety Car
Joined: Sep 2001
Posts: 4,150
Likes: 551
From: Glenbeulah Wi
If the "S" terminal on a CS-anything alternator isn't used, the internal regulator uses the voltage at the B+ Output as its reference point. At high output current, the OEM #10 gauge red output wire will present significant voltage drop. I've seen as much as a couple of volts drop between the alternator output and the battery terminals. Using the S terminal causes the regulator to maintain set voltage at the S terminal rather than the Output. In a C4, the other end of the red S wire is usually at the battery junction block. The regulator will force the output of the alternator to be as high as it needs to be to overcome any voltage drop in the output wire, to maintain set voltage at the junction block.
