Alternator not charging

[John Milner]

I am having trouble getting my alternator to charge on my 68 charger. I bought a new engine wiring harness from classic industries that was wired for my electronic ignition. The alternator it was wired for was supposed to be a 70 style dual field. I am running that style. I have the green wire plugged on one field and a brown wire on the other field. My voltage regulator is a new solid state that has the internal circuit board and looks like the stock 68 style on the outside. I have the green wire plugged in the field side and two blue wires plugged in the other side. My engine has a good ground from the firewall to block. I grounded one field out manually and it started charging. Does anyone have any ideas as to what to try to make it charge?

[b5blue]

A dual field regulator would have 3 connections? (It also needs a good ground through mounting.) You say it "started charging"? Have you 12V+ at the main on the Alt.?

[Gold Rush]

Here is a schematic of my '74 charging system.  It has the dual field connection alternator so maybe this will help you.  You mentioned good connection from engine to firewall but did you make sure the ground connection from voltage regulator to firewall is also very clean?  That is vital.  There is also a possibility that the new regulator is DOA.

Keep after it.  This one should be fairly easy to isolate and cure.  GOOD LUCK!

'74 ignition  , on Flickr

[John Milner]

Thanks for the replies everyone. Now one thing I did not do was put a ground strap from the regulator to firewall. Does it need one? I wasn't sure if it grounded by just bolting to the firewall or if it actually needs a ground strap. It does have 3 connections on the alternator. The main power wire, and two field wires. All I did to test it was ground one of the fields and it started charging.

[Gold Rush]

A lot of times just bolting the regulator to the fire wall will NOT provide a good ground.  It's a good idea to scrape any paint off the regulator and firewall right at the contact point.  I also slip a nice crisp star washer in between the regulator and firewall.  The washer teeth bite into both surfaces.

OH, forgot to add...   Put just a bit of dialectic grease on the places you remove the paint.  It will prevent rusting and not goo up the firewall too much.

[b5blue]

I ground the engine to the regulator and firewall.

[Nacho-RT74]

BROWN WIRE TO THE ALT FIELD? It must be BLUE! Same blue arriving to regulator! BROWN must get to + lead of coil and comes from ballast! But is virtually imposible to mix them those, because they are diff kind of terminals!

If you really got the brown wire to alt field, alt is getting a low voltage rate sent by ballast ( 4.5 to 9 volts depending on engine bay temp and engine RPMs )

If you grounded one of the alt fields I guess the green wire is not connected but hanging around, because the regulator works controlling the ground level, while positive is constant from ign switch.

Next.... it seems you are mixing up regulator for one field and Dual field alt?. If you got a mechanical kind reg, will work just like the old mechanical style no matter if electronic inners. You MUST get the correct regulator for dual alt field, which is the stock 70 and lates regulator.

Pre 69 mech reg and post 70 elect reg systems work way diff and can't be mixed up without be modified somehow. While green wire on mech system regulates by positive via green wire and ground is constant with one brush grounded to chassis ( non isolated ), laters system gets both brushes isolated, because one gets CONSTANT positive from ign switch on blue wire and REGULATED ground ( hence the isolation need ) on the green wire.

[John Milner]

BROWN WIRE TO THE ALT FIELD? It must be BLUE! Same blue arriving to regulator! BROWN must get to + lead of coil and comes from ballast! But is virtually imposible to mix them those, because they are diff kind of terminals!

If you really got the brown wire to alt field, alt is getting a low voltage rate sent by ballast ( 4.5 to 9 volts depending on engine bay temp and engine RPMs )

If you grounded one of the alt fields I guess the green wire is not connected but hanging around, because the regulator works controlling the ground level, while positive is constant from ign switch.

Next.... it seems you are mixing up regulator for one field and Dual field alt?. If you got a mechanical kind reg, will work just like the old mechanical style no matter if electronic inners. You MUST get the correct regulator for dual alt field, which is the stock 70 and lates regulator.

Pre 69 mech reg and post 70 elect reg systems work way diff and can't be mixed up without be modified somehow. While green wire on mech system regulates by positive via green wire and ground is constant with one brush grounded to chassis ( non isolated ), laters system gets both brushes isolated, because one gets CONSTANT positive from ign switch on blue wire and REGULATED ground ( hence the isolation need ) on the green wire.

Thanks for the replies everyone. I think I need to go back and trace some wires.  I have a blue wire that is running to the + terminal on my coil.  It did not have an end on it that would go to my alternator.  It had an end that would go on a stud.  The car runs fine hooked up like that.  My ballast resistor is a two terminal one.  It has two wires that are blue and go to the same terminal on one end, the other side has a blue and brown together that go to the other terminal.  The regulator has a green wire that is hooked to the field side while the other side has two blue wires that plug into the regulator. The alternator has the main power wire, which hooks to a stud on the back of the alternator.  There is a green wire, which I have hooked to a field.  I don't seem to have another blue wire with a female end that will hook to the other field. There is a brown wire with a female end, which I thought went to the ballast resistor, hooked to the other field.

When I bought this engine harness from Classic Industries, I received it with no diagram or instructions.  It was the one that they offered for a 68 that said it was for electronic ignition.  That part seems to work fine.  I called them and asked which type of alternator that it was for and they told me it was for a 1970 dual field style.  I'm starting to think that might not be right.  I'm tempted to try a '68 style alternator and keep my current regulator and see what happens. 

[Nacho-RT74]

Using dual field alt and mech reg ( or its elect version ) needs a grounded brush and the one coming from regulator will be green handling positive ( regulated )

[John Milner]

I ended up grounding one of the fields to the body of the alternator and it seems to be charging.  However, when I 1st start the car it will show around +30 on the amp gauge until I let it run a second and jab the throttle.  Then it settles in around +15.  I haven't charged my battery just yet and I'm sure it is a little low from all of this.  Should they normally run right at 0?  And is it normal for it to show such a charge when it is 1st started?  Thanks for all of the advise and help.

[Nacho-RT74]

Yes, is normal get charge reading after start up. The starter motor sucked out lot of load while cranking. The more you crank, the more load from battery sucked out. Then alt begins to recharge per battery request untill batt is charger back full. The more discharged the batt, the more high charge readings for more time, and the slower will go decreasing the charge readings

Yes, if everything is correct  the NORMAL reading should be 0 or close to that with small swings up and out... SMALL swings

[b5blue]

  AND your saying "Haven't charged the battery yet" puts you in the danger zone. The heat buildup from current running to charge a 1/2 dead battery is what stresses the gauge and wires. As the wire heats the resistance increases and as resistance increases it gets hotter faster. The car is not engineered to charge dead batteries just replace charge lost from starting and run systems.
  I tested my system after installing the Denso 120amp Alt. and Fleet upgrade. By leaving the radio out I could reach in and feel the Alt. gauge posts on the back of the gauge. The only time anything got overheated was with the battery discharged. (Like from excessive cranking or such.)

[John Milner]

After charging the battery it is really close to showing zero on the gauge now. I'd say it is fixed now. Thanks for all of the help with this.