Coil/ballast resistor draw drop a whole volt?

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rob_robinson87

rob_robinson87

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Ok, now that I have my new battery and it is charged (putting out 12.7 volts without car running) I was looking to where I can tie in my electric choke. Upon checking for power with key on, I find that the voltage at the voltage regulator (center pin) that connects to the key on and to alternator field, drops to 11.3 volts when the 12+ (key wire) connector is attached to the ballast resistor (and coil). Should I see that much drop? Since that same circuit runs to the alternator, I'm afraid that it will affect how the alternator charges. I have made some upgrades such as headlight relays and the jumper from the alternator to the starter relay to ease the interior wiring.

As long as the ballast is unplugged, I get the full 12 volts at the voltage regulator and of course, the alternator. Before I start ripping wiring out, I thought I would check to see if you think that the ignition switch, or coil could cause this, or would it be deeper into the wiring (such as the dreaded bulkhead connector).

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Ok, let me add to this.. Just pulled the wire off the coil, left the wiring plugged into the ballast resistor and I keep the 12.7 volts. So, the coil is pulling enough to drop everything down 1 volt.
 
I think your voltage drop is from the accessories that power up when the key is on but engine is off (KOEO) such as the indicators in the dash (oil and brake warning) the ECU and the radio if its not turned off. Is there any difference between voltage at battery and voltage at the regulator when the car is running? If there isn't there is no problem. best place to tie in for an electric choke (factory spot) is just before the oil pressure sending unit just make sure your tapping into the dark blue wire and if your running a mopar choke (not plastic 4 barrel one) that you use the choke thermister (shuts choke off after engine warms up)
 
The problem is NOT the ignition. The problem is the WIRING HARNESS

You have the circuit path from the BATTERY -- FUSE LINK -- BULKHEAD CONNECTOR --AMMETER CIRCUIT --IGNITION SWITCH CONNECTOR --through the SWITCH -- BACK OUT the SWITCH CONNECTOR -- BACK OUT the BULKHEAD CONNECTOR (on the dark blue) -- to the REGULATOR and IGNITION

ANYTHING or a combination of things in that circuit path can cause drop. Your number one, number two suspects are the bulkhead connector, and the connector and ignition switch.

To find it, you'll have to probe around. Hook up everything under the hood, IE regulator, ignition. Get up under your column, remove the little trim piece, and get the switch connector down where you can get at it. Get the wiring diagram, and check the main feed coming in and the ignition going out. If both those are low, it is in the MAIN BATTERY feed coming through the BULKHEAD, or in the AMMETER circuit. This means the AMMETER and it's connections and the in-harness WELDED SPLICE Again, you number one suspect is the BULKHEAD CONNECTOR

If the check at the ignition switch shows OK, then your number one suspect is the ignition buss going out through the BULKHEAD connector.

One way to "fix" this is to get a quality bosch relay with a connector and pigtail which has mounting holes. You can put that out near the regulator/ ballast, use the old ignition feed coming out of the bulkhead to fire the relay, run a big (30a) fuse from the start relay stud to the relay contacts, and then run the relay output to the ignition/ regulator.

Be sure to recheck after installation to be sure you actually cured it

WHY THIS IS REALLY BAD

This voltage drop CAUSES an OVERCHARGE condition. This "one volt low" makes the regulator "think" the battery is "one volt low," and so it ramps up the charging voltage until that buss becomes the regulator set point. So this means that IF the regulator is "perfect" at about 14V charging, the voltage at the battery will be ONE VOLT HIGH at 15!!
 
Haven't started the new engine. I was just checking everything over. The choke wiring I'm trying to hook up is the 12+ side of the 750 Edelbrock 4 barrel. I was trying to find a good close keyed 12+ connection before I noticed the issue.

With the + side of the coil detached, there is no voltage drop, even with radio on, interior lights, etc. With everything "off" in the car (radio, lights, etc- of course the gauges are still powered up) AND the coil connected (not running) but key in ON position, voltage drop at the voltage regulator is 11.3 volts. As soon as I disconnect the coil wire, right back up the 12.7 volts.

The coil is about 10 years old and is a Accel Chrome supercoil and hasn't run on the car in 4 years.
 
66plyValiant said:
I think your voltage drop is from the accessories
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Sorry, "not." This is a fault in the harness/ connectors/ ignition switch. That drop should NOT be there, plain and simple. My rule of thumb for this drop is

Over about .2-.3V, get concerned check the bulkhead and ignition switch, and see if you can improve it

1/2 volt or more, get serious about improving it.
 
Yeah, I thought about a relay to isolate the heavy voltage running through the ignition switch. I'm going to probe around on that some. I spent some time cleaning the bulkhead connector really well and made sure all connectors are tight there. I'll still check that out.
 
i noticed the same thing on my 67 cuda` i wired alternator output direct installed direct fed relays for alternator field and headlights. also changed ignition switch.ignition sistem still drops suply voltage one volt.i think its the fuseable link. i will probably feed the ignition with a relay also.relays are cheap and a good upgrade to the electrical systems on our old cars
 
You will need to operate the electric choke via a relay triggered from ignition run circuit. I use the 12v side of ballast resistor for trigger #85-86 terminals, and fuse the power feed to choke with 10 amp fuse.

Also in addition to cleaning and correction of all connections and conductors if needed in ignition circuit outlined by 273, don’t forget to clean battery terminal connections, as well as engine block grounding conductor, and head to fire wall grounding conductor.

Install a ground loop from negative battery terminal picking up orange box, voltage regulator, alternator case attached by one each of their mounting screws. This will put all these devices at the same potential, eliminating any voltage drop in the ground side of the circuit.
 
I added a relay for the 12v key on, running my hot directly from the battery to the new relay (where I mounted on the original voltage regulator location). I used the original blue/white wire that originally provided voltage to the ignition as my trigger. I made sure all my wiring was heavy enough to support the voltage regulator, electronic ignition, and the ballast resistor/coil. Even with all this extra work, the coil/ignition/ballast still pull the voltage down to 11.7 volts (car isn't running yet)- better, but still below the 12.4 at the battery. I'm sure that the Accel coil and the ballast must really be putting a load on the system. I didn't test long, but all connections are good. When I get it started, I'll update this thread. At this time, there isn't anything else I can do to improve anything- all terminals clean, all grounds clean, all crimps secure.
 
rob_robinson87 said:
I added a relay for the 12v key on, running my hot directly from the battery to the new relay (where I mounted on the original voltage regulator location). I used the original blue/white wire that originally provided voltage to the ignition as my trigger. I made sure all my wiring was heavy enough to support the voltage regulator, electronic ignition, and the ballast resistor/coil. Even with all this extra work, the coil/ignition/ballast still pull the voltage down to 11.7 volts (car isn't running yet)- better, but still below the 12.4 at the battery. I'm sure that the Accel coil and the ballast must really be putting a load on the system. I didn't test long, but all connections are good. When I get it started, I'll update this thread. At this time, there isn't anything else I can do to improve anything- all terminals clean, all grounds clean, all crimps secure.
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OK, photos if possible. DETAIL exactly how you wired this what sort of fuse you used, where you pulled power off of, and exactly what relay did you use? What gauge wire did you use?

You should be able to get this to LESS than .2V difference between battery and the switched IGN terminal.

BEST way to measure this is to NOT measure battery v. and then IGN v. Measure the drop directly. Put one probe directly onto the battery POS post, the other on a switched IGN point, IE the IGN power to the alternator field, or the ballast or ignition system. That reading WILL BE the "drop" or the difference between the two.

I'm using a relay box out of a Voyager or similar. Relays are or are similar to common Bosch relays. Headlight high, low, fuel pump, charging, and ignition.

No voltage is more than .2v from battery and the ignition drop is nearly ZERO.
 
Battery feed from the starter relay (all connections crimped with uninsulated ring or Packard 56 connectors and then heat shrinked)- 12 gauge. Tight and secure -runs from (brand new) starter relay to the new relay that I located at the old voltage regulator location.

Relay: 12v out has two 14-gauge wires crimped in a heavy type 56 terminal to the following:

Feed to the voltage regulator (and to the + field terminal of alternator) - 14 gauge for both-VR is no more than 4 inches away.

Feed to the ballast and orange box (again no more than 4-5 inches away).

Ground to relay is 12-gauge (4 or 5 inches long).

Used new Potter and Brumfield 40amp relay, all brand new type 56 terminals in a push-in relay base- extremely tight.

It took me a good 6 hours of careful crimping, heat shrinking, and wire routing to make sure it was perfect.

Without coil attached, absolutely no voltage drop (the ballast gets hot like normal either way). With coil wire attached, it starts at 12 volt, then after a couple of seconds drops down to 11.7. That is why I think the coil is just really drawing that circuit down. The coil hasn't been used in 4 years and is about 15 years old.

There isn't anything I can do to make it better now. I will take readings once I can get the car started and charging correctly. I'll try to get a couple of pictures.
 
Check both sides of the relay to see if the drop is in the relay or before. Then check right at the battery to see if the battery is dropping that much. Sounds like your wiring is plenty good. Regardless, feel the wiring back from the ballast to the battery and look for warm spots.

You did not fuse the wire from the start relay to the relay? You don't HAVE to as the factory wasn't, but I like to run about a 30A fuse in there for catastrophic failure. It would save burning up the harness in case of a short somewhere.
 
WHoops.. yes, I did fuse it. Now that I look at the fuse holder, I may replace it. It is a glass fuse holder (not a blade). It is a 12-gauge, but I don't like how the ends of the fuse are touching by just using a spring. If that isn't an issue, it could be later. I'll change that tomorrow when I run to the parts store.
 
rob_robinson87 said:
WHoops.. yes, I did fuse it. Now that I look at the fuse holder, I may replace it. It is a glass fuse holder (not a blade). It is a 12-gauge, but I don't like how the ends of the fuse are touching by just using a spring. If that isn't an issue, it could be later. I'll change that tomorrow when I run to the parts store.
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Well you can CHECK all along that path and find exactly where the drop is. Put one probe on the battery POS, and with the key in run/ engine off, check all along that circuit path, first at the start relay, then at the downstream side of the fuse, then the relay both sides, etc. It will show right up.


A drop that big should be making some heat, SOMEWHERE.

Another thing you can do, doesn't your meter have a 10/ 20 AMP scale? Unhook the fuse, jam the probes in each side and see what the thing is actually drawing.
 
Well it LOOKS nice, and clean. What's the master off of, you know?
 
I swapped out the glass fuse holder for a blade fuse holder (12-gauge). That was the final piece of the puzzle. Everything up to the same voltage now. I guess the aftermarket glass fuse holder (small contacts held to the end of the fuse by a spring) doesn't make a good enough contact for the strain of the ignition system. When I turn on the key, I get over 12.6 volts at all connections. Coil (through the ballast) is 7.4 volts. Even the hot at the alternator is 12.6. I also have a functioning electric choke.
 
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