Charging issue

[dartkory]

My alternator in park and while driving seems to have a good charge at 14.05 volts. But while at a light in drive it drops to 12 volts and if I have my fan on or headlights on it drops to about 10.5 volts. I have a stock style distributor with a pertronix set up in it and a msd digital 6 box and blaster ss coil.
Now I've been looking at other posts and saw a way to check for issues such as hooking a voltmeter probe to the pos side battery post and the other probe to the ign side of the voltage regulator. They say anything over .2 volts is cause for concern, mine reads .66!! Then the other test was with the car running hook one probe to neg battery post and the other probe to the voltage regulator case. Again they say anything over .2 is bad, mine reads -.05!?! Why would it be negative? And how can I fix this problem since it clearly seems to be my issue. Thanks a lot for any help! -kory

 

[67Dart273]

The NEG reading is simply the way the meter is hooked

.66 is quite a bit of voltage drop

Your car is a what, a 66? So it feeds the ammeter through the bulkhead CONNECTOR as opposed to the older separate feeds?

The voltage drop can be anything in the feed path from the battery, through all the connectors, to the point that feeds the regulator, IE the regulator IGN terminal.

So your feed path (I believe) is battery---fuse link---bulkhead connector---ammeter---in harness splice---ignition switch connector--through the switch---back out the switch connector (on dark blue "ignition run" or IGN 1 --- back through the bulkhead connector !!!AGAIN!!! and finally to the ignition system, regulator IGN terminal, and "other stuff" on newer cars

So ANY bad connections in that path, either the connections or the switch, can cause the drop. "Some of us" have gone to relays under the hood to feed headlights and switched loads for that reason.

IF YOU HAVE the older "round back" alternator you can benefit from buying a newer "square back" (72? and later) alternator, as they put out more at low RPM.

You can use the newer isolated field (incorrectly called "dual field" with an older regulator by merely grounding either field terminal, but this might be a good time to add ONE MORE WIRE and convert the system to the 70/ later system.

Do NOT allow a rebuilder/ parts store to sell you an older "round back" alternator

Roundback:

http://www.forabodiesonly.com/mopar/showthread.php?t=201739

Squareback at bottom