charging issues

-
phaelax

phaelax

Well-Known Member
Joined
Sep 3, 2014
Messages
437
Reaction score
149
Location
Ohio
Between myself and a few others, we haven't been able to figure out why my car isn't charging. New battery, alternator, voltage regulator. Had them tested (i have bad luck getting a good alternator the first time, this was my 3rd!), working fine. Triple checked my wiring on the dual field alt, looks ok. Checked grounds. Repeatedly.

The battery isn't charging when the car runs, and the car is running off the battery. I've replaced the battery wire from the alternator after the old one shorted out. If I remove the wire from where it goes into the bulkhead (which eventually leads to the ammeter) the car will die instantly. So I'm thinking the wire coming back through the bulkhead off the ammeter and to the starter relay may not be connected somewhere. Because the wiring from that relay to the battery checks out.

I've also tried running an extra wire directly from the alternator straight to the battery to see if it'd charge but it still doesn't. I'm sort of at a loss here.
 
Too bad you didn't ask here before you spent all that money

First the VR MUST be grounded. Don't just look at it.......remove it, scrape the firewall around the bolt holes, and at least the backside off the VR flange, and remount, tight, using star lock washers

"Work" the VR connector in / out several times to scrub the terminals and to "feel" for tightness.


Check the belt is tight

==========================================================

Now some simple tests, and I tend to divide this system into sections "when I think."

1.....Parts......The VR, the alternator

2.....The output wiring path, that is the battery line from the alternator, through the bulkhead, the ammeter, back out the bulkhead, through the fuse link, and to the battery. Several places there, for loose / bad / marginal connections

3.....The field wiring, which is "switched 12V" or "ignition run" supplying the VR and the blue wire to the alternator field, as well as the green wire, going from the field back to the VR

What we are NOT concerned with in the diagram below, is anything connected to the BOTTOM of the ballast resistor

Dual_Field_Alternator_Wiring.jpg


============================================================

A.....To start, remove the green field wire at the alternator. Hook an alligator clip lead to that alternator field terminal, and turn the key to "run." In subdued light (if you can) touch the clip lead to ground a few times. You should see and hear a small spark. Connect the clip to ground and get your multimeter

With the clip lead grounded, and leaving the BLUE field wire connected, probe that blue terminal on the alternator. You should see "same as" battery voltage with the key in the "run" position.

Start and run the car, watch the ammeter. It should come up to "charge."

If not, hook your multimeter to the battery stud on the alternator---the big stud. With engine off, this should measure "same as" battery. Start and run the car, again, with your clip lead hooked up to ground as before. Bring up engine RPM

If the voltage does NOT increase, IE stays down around 12.5 or less, the alternator is not charging.

If the voltage "soars" way up, perhaps 17-18V and yet voltage at the battery stays low, and the ammeter does not show charge, then there is a break or loose connection in the output wire from there to the battery.

If the battery voltage starts to climb (measure at battery) with an increase in RPM, but the ammeter does not indicate, then something is wrong, "stuck" in the ammeter, or someone has bypassed the ammeter.
 
Battery was shot, wouldn't hold a charge to begin with and was starting to leak acid. Needed replaced anyway. The alternator wouldn't pass, so it needed replaced anyway as well. The VR was cheap, figured why not.

I crawled up behind the dash to check the wiring, the ammeter isn't even hooked up, looks like previous owner bipassed it. I hooked it back up and still don't get a reading. Possibly a bad meter from the start?

I've heard mixed ideas about the two fields. Are they interchangeable? Or is their a positive and negative field? I keep finding conflicting data.

I'll try your suggestions tomorrow when I get daylight again. Btw, I have a voltmeter installed.
 
The two field terminals are electrically interchangeable

CAVEAT!!!

Make certain you check the field continuity. We've been "hearing about" a lot of them improperly sold, constructed, etc, that results in alternators with one field terminal grounded.

There should be LOW continuity between the two field terminals

And NO continuity (infinity) from either field terminal to the alternator case
 
Checked ground on VR, even ran a wire from one of the bolts to various grounding points on the car. That made no difference.

Tested voltage into the ammeter and out. The out was about 0.3 volts lower than what goes in. I "assume" that's typical usage of the gauge.

Monitoring the voltage from the battery with engine running, I see a slow yet steady decrease. Voltage off the alternator reads about 0.5 volts less than what I get at the battery, which at the moment is around 11.64 on the battery.


If my new VR is bad, could that be causing my issue? It's just a thought.
 
Yes, but easy to check. Did you do any of the tests I outlined?
 
The ammeter never changes under any condition. I checked voltage at alternator with engine to see if it matches battery, but I don't recall if there was a difference. I'll have more time this evening to play around.

I haven't checked the continuity between the fields yet.
 
OK, don't go by the ammeter, use a voltmeter. The ammeter could be stuck (damaged) or someone may have bypassed the thing.
 
After everything else had checked out, I went up to napa to exchange my new VR for another one in the hopes maybe I just got a bad unit. Sure enough, that was it.

Lesson of the day, just because it's new, doesn't mean it works. And don't buy **** that says china on it!

Thanks for helping. Oh, and the ammeter appears to work, although it only displays up to 40 and I'm using a 60a alternator. Should I bypass it? Would the extra current through it cause damage if it wasn't designed for it?
 
phaelax said:
... new VR for another one in the hopes maybe I just got a bad unit. Sure enough, that was it.
Click to expand...
I wouldn't be so sure. Electronic Vreg's are unlikely to fail and if they do something likely murdered them (shorted output wire). More likely, you were relying on the now-rusty sheet-metal screw to ground the Vreg case, which the designers thought was good enough to work for the 3 yr warranty period. Simply swapping the part fixed that temporarily.
 
You must log in or register to reply here.
-

Back
Top