Can someone explain the 70s charging system?

[Knebel]

Hey, I would like to find out how the 70s and up charging system works. mainly, does the Voltage regulator turn off the charging if it thinks the battery is charged or should I always see 13.8 to 14.7Volts?

I dont wanna chase my tail here thats why I am asking. I am starting the car, see the 14.7V. Sometimes putting load (Fan, headlights) on it it stays like that, then...fairly unexplained and suddenly I see 12.5V... sometimes 13v sometimes 13.8 (that does not change when i rev the engine) sometimes lower but thats a gauge calibration issue. When this happens and the e-fan is on, I can hear how it slows down. It then can also happen, that the Voltage goes back up after a while!?

Is that how this is supposed to be or am I looking at some ground or connection issue here? Ill be putting in a bigger charging wire soon too to see if I have loss there.

It is a dual field Powermaster 95amp alternator (puts out 60something at idle). With an adjustable 70s style voltage regulator. Its connected via relay from the battery to a junction for IGN+ with a bunch of other stuff. Does the voltage regulator somehow sense anything, even with load on it which makes it stop/reducing putting out? The charge battery output wire runs from the alternator stud through a big fuse and then to the batt+ terminal. on the batt side of the fuse is where i also get battery power for accessories that require it!

 

[Big_John]

This will get you started.

The 1970 Alternator & Regulator (Session 269) from the Master Technician's Service Conference

 

[Big_John]

Same thing, except video form with a little more explanation.

 

[Knebel]

Ok so I should have the correct 2 prong Isolated field combo...

IDK... so I see 12V sometimes when I have a load on it....another time with the same load its 14.7

 

[FURYGT]

It sounds like someone has done some creative wiring to the charge circuit on your car. You really need to explain what has been done.

If you are running that 95 amp alternator through stock wiring on that car STOP!

The factory wiring cannot handle that amperage and you risk a fire or a meltdown under your dash. You don't tell us the year, make and model of your car but a 1970 C Body likely did not have more than a 50 amp alternator unless it was a police car with heavy duty Leece-Neville alternator and associated components and you are potentially putting amperage through the cars wiring that is twice what it was designed to handle.

The factory charging circuit runs through the volt or ammeter gauge in the dash before it charges the battery and the wiring to the gauge and the gauge itself were not designed to handle that much amperage. You need to do a volt/amp gauge bypass IMHO. Google MOPAR volt or amp gauge bypass or search for it on www.moparts.org or on this site.

The short answer to your question is that a voltage regulator, if working properly, regulates the voltage depending on the draw. When you first start a car the voltage regulator can put out 14 - 14.5 volts to charge the battery and then it will lower the voltage accordingly to maintain the battery at a full charge and will vary with the load on the battery. Keep in mind that a 12 volt system is really not a 12 volt system. A fully charged battery should show 13.8 volts. Always check the voltage at the battery. Please read the above reference materials and tell us everything about your car and any alterations/changes to the charging system.

 

[Knebel]

FuryGT. I understand your concern but: Please read my original post.

Soooooo.... when the battery is not charged fully, the Voltage regulator cranks out maximum voltage til the "system?" reaches desired Battery voltage. Then regulates it down to maintain?

So lets say we are at that state, having a full battery, car is running,electric fan turns on. The voltage regulator will sense it when the battery voltage lowers, then kicks the alternator back on to regulate the output back up to maintain the loss the fan created? Fan turns off, battery charged again, voltage regulator senses this and turns down the output again? is that somewhat correct?

 

[Big_John]

Soooooo.... when the battery is not charged fully, the Voltage regulator cranks out maximum voltage til the "system?" reaches desired Battery voltage. Then regulates it down to maintain?

You are confusing voltage and current.

Think of current as the amount of flow... Like increasing the current in a river means there's more water flowing.

As needed, the alternator will increase the amount of current to maintain ~13.5 volts at the battery. If you aren't maintaining that voltage, there isn't enough current output.

You start the car and you drain the battery slightly and the voltage drops... The alternator quickly charges the battery by increasing the current and in the real world, that might take a few minutes to build the battery back up to that voltage.

A little about how an alternator and regulator works. Keep in mind when he says increases power or output, it's current he's talking about and not voltage.

 

[Knebel]

Ok, so what am I'm looking for when I have (same load on the system) suddenly a low charging VOLTAGE displayed? Maybe i have some loss in the wire.

 

[Big_John]

Ok, so what am I'm looking for when I have (same load on the system) suddenly a low charging VOLTAGE displayed? Maybe i have some loss in the wire.

Could be a lot of things and it's really hard to know from this end of the intrawebs.

IIRC, you have a lot of electrical "extras" on your car. The added current draw could be hurting you somewhere or it could be as simple as a bad connection or wire. You mentioned a relay somewhere in the circuit too and I'm a little fuzzy on how that is incorporated.

 

[CBODY67]

One question, IF the genuine police vehicles had 100amp Leece-Neville alternators, how was their wiring allegedly upgraded to handle the added alternator potential output? Just asking question, no more, no less.

Question TWO is why the need for the Powermaster 95 amp alternator in the first place? Why the need for power-hungry(?) electric fans? Just curious.

Question THREE, "relays" were mentioned, so what are they running? Sound like there is something more than just "factory equipment" on this car, to me.

Question FOUR, why the perceived need for an adjustable voltage regulator, although Chrysler sold some back then, but NOT as OEM factory equipment. They were usually used on vehicles which saw many short trips that didn't allow the battery to get fully-charged on each trip.

Be advised, too, that consistently running too much voltage in the system will compromise the durability of EVERY electrical item in the car, including light bulbs, as the Direct Connection Race Manual states. One reason to NOT use the DirectConnection voltage regulator on anything but a race vehicle with electronic ignition. I found that out myself!

The alternator does not know how much load it's producing or why, as that's a function of the alternator's design output and engine rpm. The regulator modulates that output to best fit the needs of the vehicle's electrical system (at a particular point in time). The mechanical regulators had "points" which performed that function. The FSM details how much output is allowed at particular ambient air temperatures surrounding the regulator.

GM went to a "voltmeter" in the earlier '70s on their then-new models (Camaro/Firebird, for example). It was claimed that this gave a better look at the health of the electrical system than an "Ammeter" with a needle that swung back and forth as to how much load/charge was being used/produced. One the newer vehicles, the charging is controlled by a computer module (as Chrysler's been doing for a good while). The "normal" range goes from about 12.6 volts to about 15 volts . . . and the needle can be anywhere in that range at any time. Usually more when first started and drops to the lower levels the more the vehicle is run. It's temperature-variable, too. One of those "As long as it's in the range, all is well" things.

Read the referenced Chrysler information so you'll have a better understanding of how your vehicle was designed and how it's supposed to work. Then please tell us what's been changed and why.

Regards,
CBODY67

 

[Knebel]

i have an electric fan and efi and high voltage ign and a security system. My 30something amp one wire alternator would not run that and charge the battery.

Well...whatelse oh the relay yes. The relay is triggered by the ign 12v coming from the ign switch (bluewhite wire, i believe what t was) and simply feeds a wire from the battery to a distribution spot (in place of the ballast resistor) where then all the switched 12v sources are connected. Its just the switched ign on source.

 

[CBODY67]

Thanks for those clarifications. Makes more sense, now.

 

[FURYGT]

FuryGT. I understand your concern but: Please read my original post.

Knebel, No, YOU go back and read my post, specifically:

It sounds like someone has done some creative wiring to the charge circuit on your car. You really need to explain what has been done.

Please read the above reference materials and tell us everything about your car and any alterations/changes to the charging system.

We are trying to help you out. You have not adequately explained how your charging system has been changed. Telling us the following is inadequate and leaves one with more questions. Come on, WTF does "with a bunch of other stuff etc. mean?

Its connected via relay from the battery to a junction for IGN+ with a bunch of other stuff.

I asked you to explain what has been done to your charging system but you have done so. Instead, you gave a smart a$$ response to go back and read your original post without responding to a request for more information. Excuse me for being concerned about a charging system in a car that may have stock 50 year old wiring (if your car is the '68 Fury in your avatar) and perhaps an unconventional modified charging system without describing what the relay does and what is connected to this junction box and most importantly where the voltage regulator is in the wiring. I'm done.

Thank you Big John. I was trying not to get to technical and appreciate your clarification on what I was trying to explain.

 

[70bigblockdodge]

You can think of it like your garden hose on the side of the house.
Current is flow/rate.
Voltage is pressure.
You need pressure/voltage to push flow in the direction it needs to go. Load or slightly drained batteries.
When you do not need anymore flow/current the pressure/voltage can float. If you have too much flow/current the pressure/voltage will drop off, in a garden hose it is not so much a issue, in wiring it will cause wire to get hot (slowing flow even more) creating more heat till it melts. This is the concern with stock wiring and increased output from non stock altenaltor.
Electric motors/fans are a huge draw they really have to be on their own relayed circuit direct to battery with heavy guage wire 8/10 IMO.
Hope this helps explain a little differently.

 

[Knebel]

Knebel, No, YOU go back and read my post, specifically:





We are trying to help you out. You have not adequately explained how your charging system has been changed. Telling us the following is inadequate and leaves one with more questions. Come on, WTF does "with a bunch of other stuff etc. mean?



I asked you to explain what has been done to your charging system but you have done so. Instead, you gave a smart a$$ response to go back and read your original post without responding to a request for more information. Excuse me for being concerned about a charging system in a car that may have stock 50 year old wiring (if your car is the '68 Fury in your avatar) and perhaps an unconventional modified charging system without describing what the relay does and what is connected to this junction box and most importantly where the voltage regulator is in the wiring. I'm done.

Thank you Big John. I was trying not to get to technical and appreciate your clarification on what I was trying to explain.

Alright, in my original post, I have explained how my charging system/alternator is wired, you asked if it goes through the stock wiring. I explained how it is wired, which, if you had read that would have answered your question. Yes I said it's connected to ign+ with a relay to a junction with "a bunch of other stuff",that means its irrelevant to the charging System. Come on, i am not and idiot and just wanted clarification on how the voltage regulator/charging system has to work.

 

[Big_John]

One question.... If the ignition switch is off and the relay isn't energized, is the battery feed from the alternator still connected to the battery?

This is where I'm just a little fuzzy on this. Nothing against you here or your description of the circuit ... sometimes I don't quite understand.

 

[Knebel]

One question.... If the ignition switch is off and the relay isn't energized, is the battery feed from the alternator still connected to the battery?

This is where I'm just a little fuzzy on this. Nothing against you here or your description of the circuit ... sometimes I don't quite understand.

Yes it is! its a direct path (well,through a fuse) from alternator output stud to batt+!

The relay is just to power up the ign and accessories!

 

[Big_John]

Yes it is! its a direct path (well,through a fuse) from alternator output stud to batt+!

The relay is just to power up the ign and accessories!

OK, gotcha... Just didn't want to pass by a possible problem by assuming.

Just to be curious, what size fuse?

 

[Big_John]

Assuming you've checked all the connections and wires, I'd start taking voltage readings at the battery and at the alternator when this occurs with a DMM.

My thoughts are an issue with the voltage regulator. Be sure it's got a good ground, even to the point of running a separate ground wire to the engine.

A way to check this would be to disconnect the VR and ground out the field wire from the VR. This would tell the alternator to produce maximum current so you want to have all your headlights and accessories on. This duplicates the test in the FSM or the the Service Conference slides EXCEPT we aren't using a carbon pile to load the battery. You would expect to see 14+ volts at the battery for this test. Obviously, don't run the car long like this.

 

[Knebel]

What effect has a Battery which wont hold a charge that good anymore on the running system when a load kicks on?