charging problem

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chrgrmke

chrgrmke

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Hi guys, I have a problem with my charging system, I recently did the amp meter bypass on it and now I'm getting 15 volts while it's running. I've already read some threads on here with similar problem but I've gotten to a point of scratching my head. I have excellent grounding with 0.00 ohms everywhere, I get no voltage loss that I can tell. I get 12.4 volts at the battery, and 12.4 volts everywhere else, even at the fuse panel, my bulkhead connectors are in really good shape considering it's 41 years old, not corroded or burnt. I put a new voltage regulator in so it wasn't that causing the problem, the alternator is a few years old. I'm not sure what else there is to check. Anyone got any other ideas?
 
Well it might be possible, the only difference I noted between the regulators was the old one made all my lights flicker at idle, with the new one they don't, but they both charged the same. Could the alternator be bad ?
 
The main causes of wrong (high) voltage is

Voltage drop either in ground or ignition harness

Sometimes, a battery starting to go bad

Very rarely, but can happen, a regulator out of cal

Make sure (I'm not kidding) your meter is accurate

To check voltage drop turn the key to run but with engine not running

Put one probe directly onto battery positive post. Put the other probe as "close as you can" tot he regulator IGN terminal. This might be the "high" (ignition switch) side of the ballast, or the blue field wire on the alternator.

You are hoping for a very low voltage, the lower the better. More than about .2-.3V (three tenths of one volt is too much

Now check the ground circuit. Make this test with engine running fast, first with all accessories off, and agin when on. Stab one probe onto the battery NEG post, the other onto the ground mounting flange of the regulator. Same a s above, you are wanting to see a very low reading.

Check your "running" charging voltage WITH THE ENGINE WARM. Regulators have temp. compensation designed into them.

14.5 is borderline high. You don't want above that nor below 13.5

Optimum warm is 13.8--14.2
 
Now check the ground circuit. Make this test with engine running fast, first with all accessories off, and agin when on. Stab one probe onto the battery NEG post, the other onto the ground mounting flange of the regulator. Same a s above, you are wanting to see a very low reading.



I do this with an ohm meter correct ?
 
yes ask for the floating amp regulator it will float to 90 any bump or spark will snap an older black regulator so don't ever jump any 1 or if you do carry a new box with you the silver box floats to 90 wich has 1 drawback and its frying old wiring if you have any cracked wires retape or replace or chance of a fire jumps 80%. I burned down 1 65 barracuda because I updated the alternator and the wires caught a fire before I ever new y the old wiring is 1/2 the size it needs to be and 50 years old and cracked leaving it exposed to ark . Ark and old oily and fuel dripping engine bays can really burn your azz because a $9 part or a 2 cent splice. leave the fire for the nitro bouyz good luck have a fun and safe summer
 
winstoninwisc said:
yes ask for the floating amp regulator it will float to 90 any bump or spark will snap an older black regulator so don't ever jump any 1 or if you do carry a new box with you the silver box floats to 90 wich has 1 drawback and its frying old wiring if you have any cracked wires retape or replace or chance of a fire jumps 80%. I burned down 1 65 barracuda because I updated the alternator and the wires caught a fire before I ever new y the old wiring is 1/2 the size it needs to be and 50 years old and cracked leaving it exposed to ark . Ark and old oily and fuel dripping engine bays can really burn your azz because a $9 part or a 2 cent splice. leave the fire for the nitro bouyz good luck have a fun and safe summer
Click to expand...

What in the HELL are you talking about.
 
Ok, checked the reading between neg batt post and vr, 0.00 ohms when off, between 7 and 8 ohms running, not sure if i did that right. where voltage reg gets power at ballast i had 12 volt and battery had 12.6 volts, so that's my problem, I think I'll just rewire the whole thing and start fresh. Thanks for the help, I knew i wasn't doing something right.
 
You don't read ohms you read voltage. If you follow the directions I gave you exactly it will give you what we need to know. If you measured engine off at regulator and battery and there is .6 volts difference, that .6 will be added to whatever the regulator is set at.

In other words if the regulator is right at 14, PLUS the .6 V difference, you will be "charging" (running) 14.6 "at the battery."

The "easy" way to fix it is to break the "switched ignition" coming out of the bulkhead, us it to fire a relay, and power the relay contacts through a fuse or breaker from the start relay battery stud. Then feed all your switched underhood loads from the relay.
 
The ohms reading was on the ground circuit you mentioned earlier.
 
Yeh.........but that's not what I asked you to do, and if you tried to measure ohms on the ground circuit with the engine running, it won't really tell you anything. That's because the current in the system will affect the ohmeter. If you REALLY DO have 8 ohms resistance in there, that is way way to much.

Please re--read how I posted to measure this. What you are doing is reading voltage drop.


You acually could TRY to measure ohms, but you MUST do so with engine off. The reason "you don't" is that most ohmeters are not accurate at low ohmic readings. Even a couple of ohms in the ground circuit is too much resistance.

Picture in your mind the engine bay, engine, battery. "Normally" the battery is grounded to the engine block, with a 'small' jumper from the battery to the body. Additionally, there is normally one or two other 'small' jumpers from the engine to the body.

So "hopefully" we now have the battery ground going from battery post..........battery clamp........cable..........engine block.........jumper to body

While at the same time, we have the path from battery post............clamp........jumper.......to body.

The regulator MUST be clean, tight, grounded to the body. MUST. If there's any question, remove, scrape the mounting clean, and remount using star washers. If the bolts are loose / stripped, they MUST be repaired. There is no option, or it will never regulate.

So "now", hopefully, we have the regulator finally grounded to the battery.

Effectively if you put a sensitive voltmeter onto the battery GROUND post, and the regulator mounting ear. the voltmeter will measure any voltage drop (while in operation) between battery ground and the regulator ground "point."

Just like the voltage drop in the "hot" side, ANY drop in the ground will ADD voltage to the regulator "set point"

Let's "say" there is 3 tenths drop in the hot side of the harness, and 3 tenths drop in the ground. That's over 1/2 volt. So if the regulator "just happens to be one that's on the bit 'o the high side, let's say, 14.2, NOW you have 14.2 plus .3 plus .3 for 14.8 volts!!! That, really, IS about the borderline. Most healthy batteries, 'specially on long trips in hot weather, will "use water," smell, and bubble over enough to make a mess in the engine bay after a period of time / miles.
 
ok, sorry about misunderstanding what you wrote.

here is the following checks i did this morning.
batt voltage at rest was 12.47 volts

batt voltage after running and warmed up was 14.8 to 14.9 v

neg post to vr ear was 0.09 v with no load.

neg post to vr ear was 0.31 v with headlights on.

voltage at battery at 14.8 volts and had 14.2 volts at high side of ballast.

off subject for a second, should i get a resistance reading on ballast resistor with an ohm meter?
If I am supposed to get a resistance reading with an ohm meter, then I may have a bad ballast because my check on the ballast gave me 0.00 ohms on both sides, it's a dual ballast.
 
You have to check the ballast resistance with all wires (or at least both wires on either end) disconnected.

If you disconnected the wiring and showing zero ohms, then your meter is not accurate

Here:

http://www.mymopar.com/index.php?pid=115

Notice that one side (this varies a bit) is the same resistance as the "single" ballast below. The 5 ohm side was only used on older Mopar ECU boxes to supply the box. This was "designed out" somewhere along the line. None of the aftermarket boxes know of use a "dual" ballast

Not knowing "how" you took the reading at the high side of the ballast, it may be meaningless

We are having a disconnect, here. There is a REASON that I detailed EXACTLY how to take these readings. This is so that I KNOW how you took them, as if "I were standing there" so that I know what you did and what it means

Please review my very first post:

67Dart273 said:
To check voltage drop turn the key to run but with engine not running

Put one probe directly onto battery positive post. Put the other probe as "close as you can" tot he regulator IGN terminal. This might be the "high" (ignition switch) side of the ballast, or the blue field wire on the alternator.

You are hoping for a very low voltage, the lower the better. More than about .2-.3V (three tenths of one volt is too much
Click to expand...
 
I have checked other ballast resistors with this meter and got readings on them, i'll change the battery in my meter and test again.

I did remove the wires when I tested the ballast.

To check voltage drop turn the key to run but with engine not running

Put one probe directly onto battery positive post. Put the other probe as "close as you can" tot he regulator IGN terminal. This might be the "high" (ignition switch) side of the ballast, or the blue field wire on the alternator.

You are hoping for a very low voltage, the lower the better. More than about .2-.3V (three tenths of one volt is too much



I did this but it was hard to tell because the voltage on the battery was dropping, voltage dropped into the 11 v range. I tried this test also while it was running and had 14.8v at battery and 14. 2 v at ign side of ballast

my car is a 73 model and has a 5 pin ecu and dual ballast


perhaps my battery is on the way out the door.
 
When you make the test as I suggested, you do not run the starter, is that what you are trying to do?

The battery cannot possible drop much during that short test, or it would never crank the engine at all.

But your running test "actually" shows what we want. You have the DIFFERENCE between 14.8 and 14.2. The 14.2 shows that the regulator is trying to regulate "at that" voltage. That is, it is looping to maintain it's "sense" point (the regulator IGN terminal) at 14.2. The fact that the battery is running HIGHER means that the voltage the regulator "sees" from the battery is LOW.

In other words you have a .6 voltage drop between battery........through all the harness and connectors and the switch.........to the regulator.

An "easy" way to "fix" this is to install a relay to feed the ignition / regulator
 
ok, thanks, I was going to put the headlights on relays. I'll add another for the regulator untill I can get a new wiring harness.
 
I've started getting high voltage following higher engine rpms. At idle I have 14.3 volts and at high rpms it's as high as 15.5. This is checked with my dash mounted volt meter and a digital multimeter.

I changed the voltage regulator and got the same readings.

I checked your test out and have a few questions. I freely admit that the charging system is one of my weak points so be gentle. No ego here. I am a dumbass on this.

First off can you explain "voltage drop"? When I think of voltage drop I think of losing voltage due to resistance- for instance by a poor connection or a long distance over a wire. How does this test check "voltage drop" in the car?

Below are the results of the first set of tests you outlined:

On the first test I connected to the dark blue field wire at the alternator and the positive battery post with the ignition switch to "running" and the engine off. With the meter set to DC voltage I got 12.56. Pretty much straight battery voltage.

To test the ground circuit I'm assuming I need to switch the meter to read ohms now because I'm reading from one ground point to another?

With the meter set on 200 ohms it was .9 when I first hooked it up.
With the engine running fast it was .8
With the headlamps on running fast it was 15.0

I ran a 10awg jumper wire from the negative battery post to one of the regulator mounting bolts.

1.0 engine running fast
12.3 engine running fast with headlamps on.

The final running charging voltage test was the first thing I did as you saw above.

What do you suggest next?

I followed that wire coming off the regulator ignition terminal on my factory wiring diagram and through a couple of splices it kind of goes all around.
 
You confused me with part of your post

"Voltage drop is caused by resistance in a circuit. All circuits have some resistance, it's just that "usually" such things as wire, connections, and switches have such a tiny amount of resistance, that you almost cannot measure it. This is GOOD Otherwise, you might burn down your house (or even your car)

On a factory wiring harness, the voltage regulator IGN terminal IS not only power for the regulator, but the SENSING terminal, from there to ground

So "ground" must be same as battery NEG (voltage)

And hopefully, the IGN terminal should be the same voltage or as close as we can make it to battery + voltage

DO NOT try to measure resistance (ohms) Use low voltages scale on your meter. If you don't have "auto" ranging post a photo or the brand / model of your multimeter, and we'll help you set it up.

Picture in your mind the path the battery "might" take from NEG post to the regulator mount flange.

From the battery NEG terminal, the battery clamp, the main ground cable, to the engine block.

From the engine block there should be a ground jumper to the body

There might ALSO (or instead) be a ground pigtail from the battery NEG clamp to the body.

ANY of these points (additive) might have some resistance---rust, corrosion, loose.

The grounding right at the voltage regulator to the body can and usually is a culprit.

So what you do is...........

with the engine running "fast idle" make the following test first with all accessories off

and again with lights, heater, etc turned on.

Stab one probe of our meter right into the top of the battery ground post. Stab the remaining probe into the mounting flange of the VR. This is with the meter set on LOW VOLTAGE. You are measuring across all the connections, good and bad, on the "road" from battery NEG to the VR mounting flange.

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

The same thing is going on down the "roadway" from the battery positive post, through all the wiring, bulkhead, connections, and back, on the way to the VR IGN terminal.

This is what you are checking following:

Engine stopped, Key in "run"

Put one probe on switched 12V ignition, the other probe on battery POSITIVE.

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

In BOTH the above tests, you are hoping for a very very low reading on your multimeter, the lower the better. More than 2--3 tenths of one volt means you have a voltage drop problem

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

If these above tests check out, I would RUN THEM AGAIN and read this again to make absolutely certain. Re--check your charging / running voltage.

If the above tests don't show anything, and the charging voltage, WARM, is more than 14.5, Replace the regulator. ( I guess you already have?)

If that doesn't cure the problem, I would try and swap in a known good battery.
 
I can understand this better if I know what's happening and why.

I'm still fuzzy on reading voltage from one ground (the battery negative post) to another (the mounting flange of the VR) Can you explain where the voltage would come from? I would expect there to be no voltage at all going ground to ground. That's why I thought I'd be reading ohms (resistance) in that path between the battery post and the mounting flange but now rereading your previous posts I see that was wrong. I had only printed out your first post and brought that out to the garage.

If the ground contact between the VR flange and the body or any other contact in that path between the battery post and the VR flange is bad, does a small amount of voltage backfeed from the VR to the battery post through the meter giving you some sort of a voltage reading? Is that what happens with a bad VR ground?

Next question.

"Put one probe on switched 12V ignition, the other probe on battery POSITIVE."

"switched 12V ignition" as in the IGN terminal on the VR, correct?

I hope I don't sound like a total idiot here. Thanks for your patience.
 
I will try to explain about voltage drops. It goes back to Mr. Ohm, he figured out the relationship between current, resistance and volts. V = I x R. An Ohm meter applies a know regulated current, and measures the voltage to measure Ohms. The meters are are designed to force only a very small current, and also limit the maximum voltage. This is done so sensitive electronic circuits may be measured without damage. Ohm meters are only used in unpowered circuits, because the circuit currents and voltages will result in improper readings or damage meter.

An Ohm meter does a poor job measuring low Ohms. The voltage method is far better. So if current is flowing, measuring voltage across the resistor, shows the is a drop. If you do not know the current, you still know the voltage drop will be enough to be a problem. A few tenths may be OK. A few volts is not.

A regulator is simple, it measures the IGN voltage with respect to the case ground. It has an internal voltage reference set to about 13.8V. If the IGN voltage is less than 13.8V the regulator output goes low, pulling one field wire low. The other field connection is powered by IGN, so the field is energized. The current builds and the alternator responds, increasing voltage. If the voltage increases above 13.8V, the regulator output opens, shutting off energy to field. All this happens fast, the field is controlled in an on-off fashion, but the field current ramps up and down because of the inductance, it smooths, the voltage, along with battery, also a good filter and storage unit.

So that ground at the regulator is very important, it serves as the measurement reference point on the input, and also has to supply the ground return for the field current. All hell happens with a voltage drop there, because of unstable operation, the output, results in a change in perceived input voltage.

So follow all that 67dart273 suggest, it is all good. Not because I said, it follows all the rules of Ohms law, good trouble shooting skills and more.
 
Robj said:
I'll upload the photo of the meter while I digest what you've written. I appreciate the help.
Click to expand...

Ok to do the two tests that I outlined, move the pointer of the switch to upper left, about 10 o' clock, and start on the 20V scale. If your don't read anything, switch down one at a time until you get a reading. HOPEfully, doing these two tests, you will end up in the 2 or even 200mv (200 millivolt) scale. A millivolt is one / thousands of one volt, so 200 mv is .2 volts, or 2 tenths of one volt.


Robj said:
still fuzzy on reading voltage from one ground (the battery negative post) to another (the mounting flange of the VR) Can you explain where the voltage would come from?

If the ground contact between the VR flange and the body or any other contact in that path between the battery post and the VR flange is bad, does a small amount of voltage backfeed from the VR to the battery post through the meter giving you some sort of a voltage reading? Is that what happens with a bad VR ground?
Click to expand...

That is basically it. The VR draws current partly because of it's internal components "in operation." ANYTHING that draws current is capable of causing a voltage drop. Sometimes the drop is so small you simply cannot measure this drop. Picture in your mind a simple battery and light bulb. You have a light bulb connected by wires to a battery. Now remove one wire, and replace it with a REALLY small wire, that is REALLY long. Hundreds of feet long. NOW this wire, both because it is long and small, can start to have some RESISTANCE that we can measure.

Your multimeter DOES NOT draw very much current. This means that it does not CAUSE voltage drop in the kind of situation in which we are using it to measure. If you were now to take your light bulb, "in operation," with the hundreds of feet of wire, and were to hook your meter probes at each end of that hundreds of feet, you would read a small voltage. This hundreds of feet of wire, in fact IS a resistor. The current flowing through the light bulb causes the voltage to "drop" as it goes through the resistance of the wire

Your VR ground is the same. Let's talk "backwards"

Power comes from the battery to the VR IGN terminal, and operates the VR, which draws "some" current. Now it has to get back to battery NEG, but it CANNOT because there is a poor connection to ground---and on back--- to battery negative.. This RESISTANCE in the poor connection causes a small voltage to show up there right between the VR case and the battery.

To put this in EXTREME terms, if you were to remove the VR completely from the firewall, and "do this test"--------one probe on battery NEG and the other on the VR case----you would read FULL BATTERY VOLTAGE. This voltage then, can be anywhere from battery voltage down to zero ---- depending on "how good" the connection is between the VR case and the battery NEG

Robj said:
"Put one probe on switched 12V ignition, the other probe on battery POSITIVE."

"switched 12V ignition" as in the IGN terminal on the VR, correct?.
Click to expand...

Exactly so

There are many terms "we" use for switched ignition. Ma calls it "IGN 1" on the diagrams, sometimes we call it "ignition run."

This comes out of the bulkhead from the switch, and depending on vehicle model / year and accessories supplies several things

ignition system

VR "I" terminal

Alternator field on 70 and later

idle solenoid on some cars (smog)

distributor retard solenoid on some (smog)

auto choke heater if used

and a couple of other smog "doo dads" on some models and years.

THIS voltage IS the operating voltage AND the "sensing" voltage for the VR. If "all this stuff" which it powers is low in voltage, the VR will "think" that the battery is low----and crank up the charging voltage.

IN A CASE where a resistance in the ignition voltage is LOW, a DIFFERENT way you can check it is as follows:

With engine running, "normal" at fast idle, IF the VR is working properly, the IGN terminal of the VR will measure right at 13.8--14.2 (14V) LIKE IT SHOULD

But if there is "drop" in that circuit, the battery running voltage will measure HIGHER than 14. This is because the VR is simply maintaining it's "setpoint" or "sense voltage" right at 14 just like it should. But because the HARNESS and wiring, connections, switches, are DROPPING this voltage, the alternator is actually supplying HIGHER than 14V "to the battery."
 
Dell do you mind if I post the pic you drew for me to help out ?
it helped to beat it into my brain. LOL
 
First test

"Engine stopped, Key in "run"

Put one probe on switched 12V ignition, the other probe on battery POSITIVE."

Results:
The meter set on the 20v, the key on run, one probe on dark blue wire at alternator and the other on the battery positive post. 12.6 volts

I moved the one probe from the alternator to the dark blue single wire side of the ballast resistor and got 11.58 volts.

I then rechecked the battery directly between it's two posts and got 12.6.


Second test

with the engine running "fast idle" make the following test first with all accessories off

and again with lights, heater, etc turned on.

"Stab one probe of our meter right into the top of the battery ground post. Stab the remaining probe into the mounting flange of the VR. This is with the meter set on LOW VOLTAGE. You are measuring across all the connections, good and bad, on the "road" from battery NEG to the VR mounting flange."

Results:
Accessories off, engine at fast idle, meter set to 20v: meter read 0v
Meter set at 200m: meter read .02v

Heater fan and headlights on, engine at fast idle, meter set at 20v: meter read .02v
 
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