big volts

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barbee6043

barbee6043

barbee 6043
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Shepherd, Texas ( SE Tx)
72 duster 225 slant, points, been sitting a lot since last fall.

always been running driving car. the batt, is new. reads 12.6 at the battery, when running the ballast reads like 16.5 and 18.5 v. ( key on, ign 1, I get 13-15 v and 16 -18 v. the meter bounces all around) I ground the meter at the battery and scrap it on the outer casing of the vr, the meter reads 6 or so v.

the vr is the flat case type not the earlier type. bad VR or ?????

I found this my accident. I h from engine. the have 3 good grounds at the engine. I have cleaned the firewall and back of vr.........?
 
The regulator is not grounded properly. Scrape or sand the front and back of the regulator where the bolt goes through. also clean the paint off of the firewall where the bolt goes through. This should fix things.
 
superchargeddrt said:
The regulator is not grounded properly. Scrape or sand the front and back of the regulator where the bolt goes through. also clean the paint off of the firewall where the bolt goes through. This should fix things.
Click to expand...

yep , hardly any ground. it should read 0 - .2 at the very most. if it is still overcharging, the VR probably needs to be replaced.

read through this thread. I know it pertains to my 73 , but the theory is the same.

http://www.forabodiesonly.com/mopar/showthread.php?t=173673&highlight=charging+issues
 
i drove this car to work occasionally (65 mi) last year. first time i left the house the headlight switch went south. but never any electrical problems after.

I put a " reconditioned " battery in it other day, but havn't been anywhere.(SUSPECT!???)

when I saw these volts, I cleaned the firewall at the VR and back of it, cleaned the batt --- to engine block and rad support, and added 10 gauge wire from eng to f irewall! ( only reason if was even checking volts here was to get some figures to help diagnose another car with "problems"! LOL

after supper, I will switch batteries. if no change I will tomorrow set out to do all the checks you included. No ONE ever said anything is easy!!??? LOL

thanks for the input..
 
-If cleaning the VR ground doesnt do it, then perhaps this;
-It seems to me that the charge current is not getting back to the battery.
-Juice goes from alt to port"P" on the bulkhead connector, then to the #1 splice(somewhere under the dash),then to the ammeter, then back to the bulkhead connector,port"J" this time, then to the fusible link, then the binding post on the starter relay called "B", and finally to the battery.
-Getting back to the #1 splice;There are 6 wires spliced together in the harness there. Two you already know; the feeds from the battery and the alternator.The other 4 are feeds to; the ignition sw,the fuse box,the headlamp, and the horn.
-From the ig sw. RUN side; power is fed to the regulator and the ballast.

-Heres the thing; if everything is connecting properly, the voltage should be about the same everywhere in this circuit. Its all one long series circuit.
-Since the ballast is receiving a high voltage, that means everything from the alt to the #1 splice to the ballast is connecting.So the problem must be between the splice and the battery.But since it runs, that means it cranks, so power is obviously getting from the battery through the splice to the ig sw.
-So its a bit hard for me to understand how its possible for one end of the circuit to be at 16+ volts and the other end to be at 12.8volts.
-I tell you what;With engine off, measure the voltages at the battery and at the alt output stud.They should be close to the same, because they are pretty much opposite ends of the same wire.If theyre not nearly the same, I would do two things. First I would check for a pretty substantial off-draw.If none found,I would then check the following; the "J"port at the bulkhead connector(this is probably the number 1 problem spot on our old A-bodies),the fusible link,the binding post at the start relay,the ammeter connections,and finally, the #1 splice ( this splice super rarely makes trouble).
-Well I better not forget the battery itself.I suppose it could have an internal problem.
-Oh, in case you need to know; the "J"port is where the fusible link enters the bulkhead. I believe its the center connector, bottom right.And the "N" port is the same center connector, top left corner.
-Ive been wrong before, so I hope its the VR ground
 
If none of that works then fart on it.
 
after supper yesterday, I did put another good battery on it and checked the batt, vr, alt outpost post, and ball with KEY ON. getting about the same reading except when I put meter to body of VR and gr at batt, the reading was less 3-5 V rather than 8-10! LOL

did basically the same thing to this second batt, got about the same readings except again less at the VR body. AND with this second battery, the alt bug lug showed 14.7 instead of 16-18...

I can see the starter relay and VR are showing age. I will pull on an new VR I have and a starter relay off another car and get some readings.

I can also run some of those other tests 73 AbodEE listed. my meter is not old at all but is cheapo H F model. it will sometimes BOUNCE from like 1 V to 18 getting these weird readings. thanks for the help and I will list results back later today..
 
barbee6043 said:
after supper yesterday, I did put another good battery on it and checked the batt, vr, alt outpost post, and ball with KEY ON. getting about the same reading except when I put meter to body of VR and gr at batt, the reading was less 3-5 V rather than 8-10! LOL

did basically the same thing to this second batt, got about the same readings except again less at the VR body. AND with this second battery, the alt bug lug showed 14.7 instead of 16-18...

I can see the starter relay and VR are showing age. I will pull on an new VR I have and a starter relay off another car and get some readings.

I can also run some of those other tests 73 AbodEE listed. my meter is not old at all but is cheapo H F model. it will sometimes BOUNCE from like 1 V to 18 getting these weird readings. thanks for the help and I will list results back later today..
Click to expand...

You are still getting too much voltage on the case of that regulator. Try, as a test, running a wire directly from the battery negative post to the case of the regulator. This will assure that the case of the regulator is at the same ground potential as the battery. Keep us informed.

Glenn
 
update. I went out and put on new VR. it shows no reading at the case. GOOD>I have also wonder about my HF meter. I also cleaned off the bulkhead where the two big hots wires go in. they look good, the terminals looks pretty good, a very minute bit of "green". cleaned it all with copper brush.

NOW I check batt =, reads 12.5,,, the alt running is get 17-18 at big post, and 12.5 at green file wire ( 2 field posy alt). I try to get reading at the ball. NOTHING.

yesterday, when getting these big numbers, the meter would sow 1 V. then bounce around 15, 16, 18 etc..... I will see if I can find some new batteries for the meter.

I havn't changed the starter relay, probably run to town and get a new one after a while.

I have a new ballast I will put on there. I tried to get a reading at the VR with it running, but then it showed no reading????

new update!! I just back out and changed to a new ballast. NOW it all reads this running: batt. 12.5 v,,,, I was getting 12.8 at the new V R, and new ball reads 9.4 and 11.8 ... the alt reads 12 at the big stud and 8 at the green field wire.........

with just key on, I get 12.5 at batt... ballast l is 11.6 both terminals, .. at the VR I get 11.6 out of both the green and blue wire there. why would I get any reading at the green field wire at the VR ???????
 
cause the key is on.
If you are only getting 12vdc at the output stud of the alt, and reading 12.5 at the battery, then the alt is no longer charging. Now it may be that its defective/broken or it may be that the field circuit is not working.

"with just key on, I get 12.5 at batt... ballast l is 11.6 both terminals, .. at the VR I get 11.6 out of both the green and blue wire there. why would I get any reading at the green field wire at the VR ?"

Because that is a series circuit. The battery voltage is coming through the ig sw RUN down the blue wire to the VR,to the alt field coil,out the coil to the green wire ,and back to the VR.There will be a voltage drop from end to end, but its all one long string.
In a perfect system, with the engine not running, there would be the same battery voltage every where throughout the system.(except for certain dash gauges.)
In a perfect system, with the engine running, there would be regulated alternator output every where throughout the system.
The battery voltage is very nearly always below the VR set-point voltage. So right after you start the car,and the alt is fired up by the ig sw through the VR, it begins to pump out DCvoltage. It pumps it out hard, every where, and it only takes a moment to get to the VR down the blue wire.The VR says whoa there buddy, thats too much.It then immediately starts leaking what ever voltage is higher than the set-point.It leaks it from the green wire to ground.As soon as the voltage drops below the set-point the VR stops leaking, and the blue wire voltage rises. Thus it regulates the system voltage by varying the field leakage.The VR set point can be anywhere from a low of about 13.2 to a high of about 15.2. It varies by manufacturer.As a very general rule, on our classics,the charge voltage runs about 13.2 to maybe as high as 13.8. And thats about what you should be seeing everywhere except on the coil side of the B-resistor.Here it should start out near that same reference voltage, when its cold, and the voltage should drop as it heats up. Which doesnt take long.
So thats why the VR case has to be well grounded; so it can leak. And why the alt has to put out DC voltage, so the VR knows whats going on. And why the VR needs to see battery voltage at the blue wire.
High resistance connections anywhere in the system between the battery and the alternator, can fool the VR into thinking it ought to leak less and therefore puts out more voltage.
Do you know how to perform a full-field test? You will need to perform one on your alt to prove its good or not. Also you will need to check it for A/C output.
 
If your meter is going from 1vto 16/18 when on the DC mode, switch it to A/C mode. I bet one or more diodes are bad and its sending A/C out, through the system. The VR wont know what to do with that. Neither will the battery, or anything else except light bulbs. Bulbs run just fine on A/C. That may be why your headlamp sw quit. That would also explain the high and low voltage readings on the two ends of the same circuit.
Check it out.
 
the full feld test showed no increase in output, the back of the alt was not magnetic. I took it town, alt tested good. ?????
 
Thats not possible!
-What I mean is one of you is in error. If the alternator truly is good then a full field test will force the alternator to max output; whether you do it, or someone in town does it.So who are you gonna trust?Did they do a load test on it or just a voltage test?
-If you full field it, and the alt goes to max output, then whatever voltage comes out on that stud, should be seen throughout that circuit, anywhere between the alt and the battery, within about 5 %.
-The test points are; alt stud, port "P", #1 splice, ammeter(both sides), "J"port, Fuseable link, stud"B" on the starter relay, battery positive, ig sw feed, ig.run, port"N", VR blue, B-resistor feed blue. That same voltage should show up on the other feeds too, namely; headlamp sw, fuse box, and horn relay.

Have you pulled the wiring diagram up yet?
 
This should be fairly simple to solve. Since I am also simple I will tell you what I think. I think rather than jumping all over the place you should start over as if you had done nothing yet.

Get a wiring diagram and some colored highlighters. Trace the circuit in question so you know where to test. In order to properly regulate the alternator output the voltage regulator needs to know the system voltage. If I remember correctly, the dark blue wire at the regulator is the voltage sense from the ignition switch. This is essentially the input that controls the alternator output.

The alternator output goes from the alternator output stud to the battery. If there is a ammeter gauge the circuit goes through that. In either circuit, without any resistances the voltage should be essentially the same at all points in the circuit.

What you need to do is a voltage drop test. This is exactly what its name implies, as it is a test for voltage drops in a circuit. A voltage drop test is not valid unless the circuit is loaded, so the test must be done with the circuit live in the condition in which it is normally used. In this case, engine running because the battery is the load for the alternator output. If the voltage at the battery does not match the voltage at the alternator output you need to determine whether the fault lies on the input side or the output side of the circuit. If everything is working correctly the voltages on the input and the output sides should be within 1/2 volt of each other. The mistake most people make in testing electrical circuits is they forget about the ground return. The same applies, all points in the ground return circuit should be the same level as battery negative. This includes the body and the alternator case.

If you do not have system voltage at the blue wire on the regulator, then work backward in the circuit to the ignition switch. Now look at the diagram to see where the ignition switch gets its power sourced. Probably on a red wire from the ammeter. That is essentially where the input and output sides of the charging system meet. Continue until you find where the bad connection is located.

You can figure it out. Use the diagram. Use the colored highlighters in different colors for different parts of the circuit. It is just like reading a road map except the diagram is the road map for the electrical system. If you have more questions, just ask. There are a lot of smart guys here willing to help.
 
I admit to being "auto electrically" disabled!! LOL yes I have the FSM.

earlier today i did the " full field" test. it showed no increase in volts.... the clip at the alt field terminal must have moved up against the case.?? I took the alt to town, to parts store, tested good, came back home and did the test twice more, all tests read charging very well.

so at this point I have cleaned all bulkhead terminals, new V R, fully charged battery. I did pickup a new starter relay, but did not have time to put it on, but I did warm the engine good and tested volts key on,,,, and running, this is what I found:

KEY ON:batt.12.7..... ballast 6.2, 11.3,........ vr 11.7, 11.8

running; BATT 12.4,...... BALLASt 9, 12 .....ALT BIG POST 13.0..... VR 12.1, 12.2, alternator 13.0

readings at coil key on + was 6.3 and ---- was .1

at coil running + 9.5 and ------ 6.8

one thing I really need is what are the normal volts at all points both key on, running, and ign 2 when I'm trying to trouble shoot a non runner. i'm always trying to piece a roller back together.

since the old VR was grounded very good and the engine grounds are cleaned and grounded in 3 places. and the body of VR was showing 6-7 volts, I have to feel it needed replaced, it looked plenty old. the starter relay looks plenty old too, but does start the car easy.

I never want to just throw parts at them, but just what is needed!

I do appreciate everyone that try to help my electrical problems.
 
Have you checked for a battery off-draw yet?
When you rev it up, say to 2000rpm, what happens at the alt stud? and at the Bat +?

Think of this circuit as one long wire, with the bat+ on one end,and the alt output stud on the other end. In between are the Fuseable link, the ammeter, and the #1 splice, plus their various connections. Thats all there is to it.So whatever is at the stud, should be at the batt+, within about 4or5%.
From the #1 splice a wire goes all the way to the ballast resistor. On route it passes through the ig sw"run", and various connections, and up to but not through, the VR. Thats it.So whatever is at the #1 splice should be at the VR blue, within 4or5%. and all should be at battery voltage with the engine off/key on. And all should be at Alt output with engine running, again within 4or5%.
Forget about whats happening at the coil or ballast for a while.
Concentrate at getting alt output to the VRblue and batt+
There has got to be at least one high-resistance connection in that circuit somewhere.
BTW 12.7 volts at the battery is not a fully charged battery. In a lead acid battery, every cell should be at 2.2 volts when fully charged. Since car batteries have 6 cells thats 6x2.2 = 13.2 volts.

EDIT It seems I goofed, again. Lead-acid cells are considered fully charged at 2.1volts; so 2.1 x 6 =12.6 . I hate this part; So sorry
 
my last v readings showed the difference between the alt output post and the batt + to be a difference of about 5 or 6 volts. difference between the batt+ and th e VR blue wire is about 3 volts.

like I said, my meter is HF cheapie, so I would not be surprised if it is not totally accurate.

I did throttle up the eng and checked at the alt output post, but I failed to write it down. I know it did increase by not sure how much.

73 AbodEE showed a link to a lot of tests to check for wires and etc, losing volts, but I just havn't got to that yet, hopefully tomorrow.

since the ballast doesn't read 18-19 volts and the VR doesn't show 6-8 v at its case, (new VR),,, I figure I have made progress!! I will be driving this car 3 days week 65 mi, starting next week, so I am trying to get it all like it should. I have to wonder if it could have been doing this last year and fried something.???

i would love to know what volts should be at all the important points, key on, start, and run...... thanks for the help everyone.....
 
Find where the 5 V drop from ALT stud to BATT+ occurs. Should be <0.5 V. First, measure across the battery post, i.e. from post to cable clamp. Corrosion there is common and needs a yearly cleaning in MO. If across the bulkhead connector (2 terminals: in & out), then your bulkhead will soon melt since P=(5V)*(40A) = 200 W = hot! That is also common.
 
BillGrissom said:
Find where the 5 V drop from ALT stud to BATT+ occurs. Should be <0.5 V. First, measure across the battery post, i.e. from post to cable clamp. Corrosion there is common and needs a yearly cleaning in MO. If across the bulkhead connector (2 terminals: in & out), then your bulkhead will soon melt since P=(5V)*(40A) = 200 W = hot! That is also common.
Click to expand...

my mistake. yesterday, I jotted down the readings from the meter correct but when I listed it here, I should have wrote difference between the alt output post and batt + as .5 or .6 V. I just tested again, it read .2 volts difference but the engine didn't run all that long. I did check the batt + post to the end of cable , the same reading / ...... I checked at firewall bulkhead, running, 12.3 and 12.4, with just key on 12.1 and 12.3

I think I got the decimal on here now!! LOL

what did the engineer say as he watched the bridge fall? damn the decimal point??
 
barbee6043 said:
I admit to being "auto electrically" disabled!! LOL yes I have the FSM.

one thing I really need is what are the normal volts at all points both key on, running, and ign 2 when I'm trying to trouble shoot a non runner. i'm always trying to piece a roller back together.
Click to expand...

As I stated earlier, there is no point testing the system unless it is on and loaded. That means key on, engine running, preferably with the lights on. Test at idle and at fast idle.

At this point all you need to know is the total voltage drop in the system. Test the voltage between the alternator output stud and alternator case and note the reading. Then test the voltage at the battery posts, not the terminals. The difference between the two readings is the total voltage drop. Total voltage drop should be less than 1/2 volt.

If the reading is more than 1/2 volt, then you can test the positive side and the negative side separately to determine where the fault lies. To test the positive side put the positive meter lead on the alternator output stud and the negative lead on the positive battery post. To test the negative side put you negative meter lead on the alternator case and the positive lead on the battery negative post. The meter reading in each case will be the actual voltage drop in that part of the circuit. Easy.

Read that last bit as many times as it takes for you to understand it. A faulty test will give a faulty result. If you have any questions about the preceding just ask for clarification.
 
Rustedwrench said:
As I stated earlier, there is no point testing the system unless it is on and loaded. That means key on, engine running, preferably with the lights on. Test at idle and at fast idle.

At this point all you need to know is the total voltage drop in the system. Test the voltage between the alternator output stud and alternator case and note the reading. Then test the voltage at the battery posts, not the terminals. The difference between the two readings is the total voltage drop. Total voltage drop should be less than 1/2 volt.

If the reading is more than 1/2 volt, then you can test the positive side and the negative side separately to determine where the fault lies. To test the positive side put the positive meter lead on the alternator output stud and the negative lead on the positive battery post. To test the negative side put you negative meter lead on the alternator case and the positive lead on the battery negative post. The meter reading in each case will be the actual voltage drop in that part of the circuit. Easy.

Read that last bit as many times as it takes for you to understand it. A faulty test will give a faulty result. If you have any questions about the preceding just ask for clarification.
Click to expand...

I made 2 changes earlier today. I put a fresh battery in it, and replaced the starter relay, ( told in previous thread this can cause elect. problems).

I turned on the lights, heater motor, moderate to fairly high reves, readings: batt + : 12.2 alt. output stud 12.1 , and at idle : batt + 12.2 alt 11.9


the volts tested at alt output post and case are the same as alt output post and grounded at the batt.

when I tried to test for drop in circuit it had No reading.

I noticed the duster to have slight miss at idle. it is worse just then. also the dash amp gauge is showing slight discharge.

while at idle I checed the ballast: 8.9 and 11.2 the volt regulator showed 11.4 at both places. I see no readings from the VR case.

will the points/ condenser cause any of these problems????? thanks for the help guys!
 
barbee6043 said:
I turned on the lights, heater motor, moderate to fairly high reves, readings: batt + : 12.2 alt. output stud 12.1 , and at idle : batt + 12.2 alt 11.9


the dash amp gauge is showing slight discharge.

while at idle I checed the ballast: 8.9 and 11.2 the volt regulator showed 11.4 at both places. I see no readings from the VR case.

will the points/ condenser cause any of these problems????? thanks for the help guys!
Click to expand...

either not charging or not running fast enought to charge. those volts low.

no, points and condenser has nothing to do with trouble
 
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