System Charging Too High

[70PlymDstr]

Hello all, really quick before I head to work, I thought I'd share a problem the Duster is giving us right now. First of all, yes, she's running now. Lol, more on that later. But the problem at hand is that the charging system is charging too high. It can get as high as 18 to 19 volts at times. Makes the battery boil. The alternator is brand new, and has tested good at the auto parts store tester. The voltage regulator and ballast resistor are new as well. Any ideas where to start diagnosing? Thanks!

 

[jdsduster]

voltage reg. ,new can be bad

 

[barracudadave67]

It sounds like you have high resistance some where in your charging circuit. Most likely place is in the bulkhead connector.Dosnt heart to clean all the connections in it. Or it could be a bad ground some where.
Make sure your alternator is not rated to high in amps, for your system. If your system is still factory, I wouldn't go over a 60 amp alternator, and that might be pushing it, if stock.
Make sure you voltage reg is grounded properly. I scratch off the surface underneath the mounting bolts, and use star washers, between it and the mounting surface.

Sorry I can't help you more.

barracudadave67

 

[krazykuda]

If your wiring is good, then too much charge is from voltage regulator...

Check for good clean connections and then check voltage regulator...

 

[ChrisPerry]

Make sure you voltage reg is grounded properly. I scratch off the surface underneath the mounting bolts, and use star washers, between it and the mounting surface.
barracudadave67

Gotta agree with Dave. Check grounds first. Bad grounds are the cause of the majority of electrical problems.

 

[67Dart273]

This can be a number of things, go through it and TEST

1.....The alternator can have a grounded field. Unhook the regulator connector and see if it stops charging. If not, you have a problem.......grounded field

If this is ok......

2.....You might have a bad regulator or you might have a voltage drop problem

To test..........

A.......First the regulator MUST be grounded. Remove, clean and scrape, remount tight with star lock washers

B.......Run voltage drop tests. Run engine, warm, at an RPM to simulate "low to medium" cruise speed. Stab one probe directly into the top of the battery NEGATIVE post. Not the clamp. The POST

Stab the remaining probe into the mounting flange of the regulator. Stab through any paint, rust, chrome. You are hoping for a very low reading, the lower the better, zero is perfect.

Check the above first with all accessories off, and again, with everything on, lights, heater, etc

C......Turn engine off, turn key back on to "run." hook one probe to battery POS post, and the remaining to an "ignition run" source. The ballast resistor ignition feed, or the blue field wire to the alternator. You are hoping, again, for a very low reading, the lower the better. More than .3V (3/10 of one volt) is too much.

In this case, too much voltage is a bad connection in the ignition run feed from the battery. The circuit path (factory wiring) is......

Battery..........starter relay.......fuse link........through bulkhead connector........to ammeter.......through ammeter......to "welded splice".........to ignition switch connector........through the switch........back out the switch connector (dark blue IGN1).......back out through the bulkhead connector

ANY and more than one of the above items can have a problem, causing a drop

If this reading is "reasonable," let's say it's 1/2 volt or even .8V. This is high and needs to be looked at but it is NOT the cause of your trouble.

If these volt drop readings are OK, replace the regulator

 

[TylerW]

This really needs to be made a sticky. This exact question gets asked repeatedly and I'm sure Professor Ohm would rather not have to keep pasting in the same answer over and over.

The long and short of it is to clean grounds, add a couple between the engine and body and ultimately take the ammeter and associated wiring through the bulkhead out of the equation.

 

[dano]

This really needs to be made a sticky.

I second that.

I will add that there are two types of regulators. One for points, and the other for electronic ignition, when there are two of those also, which is year dependent. Typically, a points one will blow if used with electronic ignition.