1971 dart is boiling battery

-
moparorange

moparorange

Member
Joined
Feb 17, 2014
Messages
7
Reaction score
0
Location
Forest Hill
Hello,

This is my first post and my first mopar. I have a 1971 dart with a 340. I replaced the battery, alternator, and voltage regulator. The car runs fine but keeps boiling/ overcharging the battery. The car has 3 wires leading to the alternator. A green, blue, and black one.

Green: field to alternator
Blue: not connected
black: to starter then battery

The alternator only has one field connector and one ground connector. I had a higher amp alt. with 2 field connectors but the car would not charge with that one.

Any help would be great. Thanks in advance
 
You.........have.........the.........wrong........alternator.

Just one field connector is for 69 / earlier

The later ones, starting in 70, had two field connectors. The blue wire is "switched 12V" from the key and is the same electrical point as the ignition run, the regulator IGN terminal, and in some cars, a few other things like idle solenoid

The green wire is the return to the regulator

What you need looks like the one on the right. Under NO circumstances allow the parts guy to shovel you off with one that looks like the left. The one on the right is called a "squareback" and offers better low RPM performance. I believe they started using them about 73 or so

http://www.440source.com/squareroundcomp.jpg

Your regulator should look like this:




A few more things:

These old girls are notorious for voltage drop in the ignition harness. When you get your new alternator make a couple of checks. Turn the key to "run" but with the engine OFF. Probe the BLUE wire on the alternator field, and hook the other probe to the battery POSITIVE post. You are hoping for a very low reading, the lower the better. More than .3V (three tenths of a volt) means you have voltage drop in the ignition harness. ANY voltage you read in this test will be ADDED to the regulator set point.

Second test: With the engine running, and the battery "up and normal" make this test first with all accessories off, and again with headlights, heater, etc, turned on.

Stab one probe into the mounting flange of the regulator case. Be sure to stab through rust, chrome, paint. Stab the other probe into the top of the battery NEG post. Once again, you are hoping for a low reading, the lower the better, ZERO would be perfect. More than a couple of tenths of one volt means the regulator is NOT truely grounded to battery negative.

The regulator MUST be grounded, as well as the ignition ECU box, if you run a Mopar breakerless ignition.

When you get things under control, read this excellent article from MAD electrical, which points out the problems and pitfalls of the Mopar bulkhead connector:

http://www.madelectrical.com/electrical-tech.shtml

If you do not have a factory service manual, you can download one here, for free:

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

More useful stuff here

http://www.mymopar.com/index.php?pid=31
 
I boiled a battery and blew some of my light bulbs out because my new electronic (original looking) voltage regulator wasn't grounded properly. The original screws fit pretty sloppy in the original holes in the firewall and didn't provide a good ground. Something you might want to check. tmm
 
When you can stick a fork in it, it should be about done.
 
toolmanmike said:
I boiled a battery and blew some of my light bulbs out because my new electronic (original looking) voltage regulator wasn't grounded properly. The original screws fit pretty sloppy in the original holes in the firewall and didn't provide a good ground. Something you might want to check. tmm
Click to expand...
Should be a "toothed" washer on the screws to penetrate the paint and make a ground.
 
You must log in or register to reply here.
-

Back
Top