Alternator wiring questions

[element303]

Hello everyone. I am still dealing with some issues with the charging system. The starter (and in the end also the horn) would randomly just become alive while driving. I replaced the starter (since I wanted to do that anyways) both cables to the starter and alternator. Additionally installed a new voltage regulator because the battery was overcharging with the new alternator, which I think is related to the starter spinning on its own (only happens when the alternator is connected and the battery is overcharged for a few seconds.

The battery is still overcharging with the new regulator installed and I know now that the issue must be one of the cables somewhere. I want to replace all cables from the alternator today but I am a little confused how it supposed to work according to the info I found.

If the BATT cable goes directly to the battery and no cable going from the regulator to the battery, how is it being regulated then? the way I got the car from the previous owner, the BATT cable from the alternator went to the starter relay and from there to the battery. I am assuming it have to go straight to the battery. Maybe you guys can explain me a few things about connecting it correctly from scratch.

Since the issue could also be somewhere around the key switch, could you guys also tell me how I can remove the plastic behind the steering wheel safely without breaking it?
Thank you!

 

[67Dart273]

What kind of vehicle, IE is this 70 or later or 69 or earlier?

What kind of alternator / regulator do you have, that is, I know the Mexican or S. American cars use Bosch or Motorola or some other system, NOT "Mopar."

Aside from that, the main charging cable is not what does the regulating

The regulator will have some sort of exiter / sensing/ power wire from the ignition switch to the regulator

If this is 70/ later Mopar system, the regulator green wire goes from regulator to alternator field.

Ignition switch "run" power goes to the remaining field, and also to the blue REG wire

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

So far as overcharge, assuming you have compatible alternator/ regulator and it's wired correctly, the main causes are: (not in order)

1....Sometimes a battery condition, IE "bad" battery, or undercharged

2...VOLTAGE DROP in the circuit path from battery, through all the connectors and wiring, through the ignition switch, and to the regulator

3...VOLTAGE DROP in the ground circuit

4...Severe overcharge in the 70/ later isolated field alternators can be caused by a wrongly grounded brush, WHICH HAPPENS

To troubleshoot: With engine running / charging, unhook either field wire one at a time from the alternator. Each time, alternator should drop down, "not" charging.

VOLTAGE DROP. Several ways to check, here is one: Rig your multimeter direct to the battery positive post. Rig the other probe as close as you can get to the regulator blue IGN wire. With key in "run" but engine off, this reading should be "lower the better." More than say, .3V (3 tenths of one volt) you should chase this down. ANY drop there will ADD to charging voltage.

GROUND voltage drop. With engine running, charging at "fast idle" stab one meter probe into the regulator mounting flange. Stab the other probe into the top of the NEG battery post. Here again, the lower the better, zero is perfect

If the above is OK, try a different battery. If that makes no different, replace the voltage regulator.

 

[element303]

This is great. I'll go through this! I followed the cables this morning and realised that the BATT cable goes first to the gauges ( I am assuming its the black one going to the volt meter and the red one that is coming out goes to the regulator and from there to the battery (or in my case to the starter relay and then battery). Also went to the guy I bought the car from to check on his 68 dart and 73 duster and it seemed to be wired correctly, except the BATT cable (as in the picture above) was not directly connected to the battery but to the starter relay and from there to the battery. It was like that when I got the car so I didnt change it yet. I was also able to get off the casing from the steering wheel until the round plate for the steering lock and all cables in there look almost as new. Can't see any issues unless the starter problem is within the ignition switch itself and not the cables connected.

As far as the overcharging, I need to go through your list. I bought the stock fitting regulator on eBay and the alternator is a Duralast from AutoZone.

Also, the regulator is adjustable in the back. Maybe it is set to high but when it's in idle its in the 13 volt range and as soon I use the throttle its slowly rising up. I will check some more now and go through your list. Thank you!!

 

[element303]

After a while of investigating I seemed to have fixed both issues.

- The overcharging might have been a ground cable not connected properly between the alternator and the water house. I reconnected the cable and cleaned the connection as I couldn't make out any metal, just engine block paint.

- The starter was a connector from the alternator going into the inside of the car, where they are connected at the engine bay wall. The yellow starter signal cable was right next to that one and they must have touched. It seemed like the alternator cable was a little burned, probably from overcharging and getting hot first.

So far everything seems to work fine. I also connected the charging cable straight to the battery. It starts much faster now too.

Thanks again guys!

 

[BillGrissom]

Please state the year and engine whenever asking an under-hood question, especially after someone asks you, like our resident electrical expert 67Dart273.

It doesn't matter whether the ALT output goes direct to BATT+ or via the big stud on the starter relay, as long as all 3 are connected together with thick cables.

The factory didn't install a ground wire on the alternator case until the 1980's, but that is a good idea. My 1969 Dart slant once didn't charge and problem turned out to be the ground connection between alt case and bracket (even w/ a new alternator). Many rebuilt alternators come w/ a GND stud on the alternator case, so a good idea to wire it.

1968 and 1973 Dart charging was totally different. Until ~1971, cars used "high-side control" w/ a mechanical regulator switching on/off and 1-field wire to the alternator (other field wire grounded). Later cars used "low-side control" w/ a transistor regulating the field current, w/ 2 field wires to the alternator (one +12 V ignition source). So, if your friend's 2 cars were wired the same, one is no longer factory-correct.

Your over-charging problem is most likely related to voltage drops thru the bulkhead connector, ignition switch, and/or ammeter posts. A common problem. Search "MAD Bypass" before your bulkhead plastic melts.

 

[element303]

Yeah I fixed it already and stated what the problem was. Thank you buddy! Runs perfect now.