Overcharging problems

[Mattax]

so I tested the blue wire voltage at the resistor and the blue wire voltage at the back of the alternator field wire both came back at 13.8 while the car was running so clearly there’s no loss

So there is little loss between those two points but a seems to be a significant drop before the current gets to the junction at the ballast resistor.

then I put a voltmeter to the battery and the back of the alternator both came back at 14.8 and then with a heavy load 15.8 i am stumped I checked all the wiring and everything looked good.

Exactly.
Well if the wiring didn't have a shunt and other mods we would know where to look next.
It would be in the path between the Alternator output and the junction at the ballast resistor.

Your're going to have to work this out by drawing in all the mods, and then the current going to the electric fan gets drawn in (you can find the current it draws at 12 Volts that will be close enough to guess the loads.

To get you started on how to do this,
Here's what it would look like with a std alternator and wiring.

The voltage drop is occuring along the current path between the 14.8 V and the 13.8 V.

Change the current and the voltage drop through any given resistance increases.

On this stock wiring scheme, the fact there is a 1 Volt drop (and its not showing in the path from the alt to the battery) means the resistance(s) must be in the only path between those two points.

 

[carmart1975]

The schematic pictured above shows all those blue wires connected together before the regulator. Did you find that connection where they are all soldered together? It has to be there somewhere. Where does the blue wire go from the regulator?

It has to have a power source. It comes from the ignition switch but before it goes the regulator it splits off and goes to the Alternator, ballast, and choke thermostat, You have to have that soldered splice in the harness somewhere or how would it reach all 4. You must not have looked very well or your harness has been changed around.

Testing You can take 2 wires from the voltage regulator blue wire. One to the battery and one to the alternator blue wire.. That should correct the charging for a test

I did make a jumper wire from the blue wire to the battery helped the problem slightly. I also ordered an adjustable regulator so I’ll put that in also because I do not have an extra regulator laying around.

 

[4spdragtop]

Not trying to hijack, but I have an overcharge issue i believe. At idle 14.86V at battery -ve and +ve.
@67Dart273 Del, which side of ballast is the "ignition" to VR? I have been running a 70 and up charging system on 67 cuda 340 elec ign. I'm trying to check for voltage drops. Here's a pic of my hand drawn modified(70+ schematic)
Thanks

This problem is likely made worse by the added fan IF you have stock wiring. Look up this article which slantsixdan LOVES TO CRITICIZE but I post it BECAUSE it points out the why and how of the base problem. Then rather than doing what they did, repair the bulkhead terminals because you STILL NEED THEM to feed the interior, and then make up a large gauge jumper cable direct --with a fuse-- from the alternator output to the battery.

http://[URL]http://www.madelectrical.com/electricaltech/amp-gauges.shtml

[/URL]

HOW THIS PROBLEM (usually) works.

Look at the diagram in the article. ALL of the terminal points in the diagram can cause voltage drop between the battery, alternator, and back to the "run" circuit in the engine bay. The path is battery--fuse link--bulkhead connector (big RED) to ammeter--out on big BLACK--welded splice--back through the bulkhead connector and to the alternator

The DROP to the VR starts at the same place, and after the welded splice goes to ignition switch connector-- through the switch -- back out the switch connector on BLUE "run" wire--out the bulkhead connector --and into the engine bay where it branches off, feeding the ignition system, the VR, the alternator field on 70/ later, electric choke if used, and smog doo dads on later cars.

THIS DROP causes the VR to "think" the battery is low, and ramps up the alternator until the blue "under the hood" meets 14V. BUT THE BATTERY IS ON the other end of the voltage drop so it sees 15V or so, whatever the amount of the drop

HOW TO CHECK

With key in "run" but engine stopped, stab one probe of your meter into the top of the POS battery post. Stick the other probe as close as you can get to the VR IGN terminal. On 69/ earlier, this would be the IGN terminal at the VR. On 70 later, the "key" side of the ballast resistor.

Whatever you measure there, let's say 1.5V, is ADDED to the VR set point. So if the VR is properly at 14, then the battery is gonna see 15.5

CHECK THE GROUND PATH

The ground, too can have voltage drop. Run the engine at fast idle, with engine warm (The VR is voltage vs heat sensitive)

Stab one probe into the battery NEG post and the other hard into the VR mounting flange. The less you read the better, zero is perfect. here again, ANY voltage you measure will be ADDED to the VR setpoint at the battery. Improve grounding.

View attachment 1716371543

 

[4spdragtop]

OK so i have 11.84V at battery +ve and -ve not running. Key ON, NOT running (1st 2 picd)batt +ve to ign 1/run on ballast(to male spade terminal with everything connected) i get 1.6V.
3rd and 4th pic, Key ON, NOT running. Batt +ve to Blue on alt stud( Fld +ve), i get battery voltage, =11.84V.

 

[67Dart273]

LOL, Steve you should have started a new thread. Too late now!!! If the battery is 11.84 it is low, undercharged. Easiest way to determine which side of ballast is which is to just measure.

1... Turn key to run, measure to ground each side of ballast. Highest reading is the key side. With OEM electronic ECU, the coil should read (varies) 6-10V. This is because of the coil drawing current through the ballast, drags down the reading.

1A if you have breaker points and the points are open, the readings will be the same. Either bump the engine, or just clip lead the coil NEG to ground for a short time and redo your readings.

1.6 V drop if that is right is a fair amount. You certainly ought to look into that. Why tho, is the battery reading lo? You had the dome lights one a lot?? etc?

 

[4spdragtop]

Thanks Del, battery may be low. I'll charge and recheck tomorrow. I did put a load test on it and it checked fine. Nothing was 9n at the time.
It's elec ign so no points/breaker.
Why I measured the blue at the alt was i couldn't "access" the blue wire from VR. At the alternator had the only "accessible" spot.

1... when i measure coil measure from batt +ve to coil -ve??
Thanks again!

LOL, Steve you should have started a new thread. Too late now!!! If the battery is 11.84 it is low, undercharged. Easiest way to determine which side of ballast is which is to just measure.

1... Turn key to run, measure to ground each side of ballast. Highest reading is the key side. With OEM electronic ECU, the coil should read (varies) 6-10V. This is because of the coil drawing current through the ballast, drags down the reading.

1A if you have breaker points and the points are open, the readings will be the same. Either bump the engine, or just clip lead the coil NEG to ground for a short time and redo your readings.

1.6 V drop if that is right is a fair amount. You certainly ought to look into that. Why tho, is the battery reading lo? You had the dome lights one a lot?? etc?

 

[67Dart273]

No to determine which ballast wire is which, measure from ballast to ground

Coil+ to ground should be the same as the coil end of the ballast to ground, same wire

Normally you can just look at them with a bone stock harness, but yours may be different. Normally the coil side of the bypass will have a dark blue, going to the coil, and a brown, which is the bypass. The "key" side of the ballast will normally have two dark blue

 

[4spdragtop]

Thanks Del, I'll chk tomorrow after work. When facing engine, LH side of ballast has 2 blue wires, 1 with tracer and 1 without. And other side has a brown and a blue like you said

No to determine which ballast wire is which, measure from ballast to ground

Coil+ to ground should be the same as the coil end of the ballast to ground, same wire

Normally you can just look at them with a bone stock harness, but yours may be different. Normally the coil side of the bypass will have a dark blue, going to the coil, and a brown, which is the bypass. The "key" side of the ballast will normally have two dark blue

 

[4spdragtop]

OK, threw a charger on battery and the damn charger crept up to over 15 volts?? WTF? Verified that with multi meter.
Unplugged that asap. Not sure ifnits the charger or the battery, but I load tested the battery and checked out. Battery is approx 10 yrs old.
Rechecked static batt V with key off. 12.7V.
Key on, got 10.57 at ballast Ign #1/run, 7V at Start side.
Started car and measured voltage direct at batt, and it steadily increased from 12 and change up to over 14 in a matter of 1-2 minutes.
That's all I had time for, hopefully more time the next few days.
Thanks

 

[CFD244]

OK, threw a charger on battery and the damn charger crept up to over 15 volts?? WTF? Verified that with multi meter.
Unplugged that asap. Not sure ifnits the charger or the battery, but I load tested the battery and checked out. Battery is approx 10 yrs old.
Rechecked static batt V with key off. 12.7V.
Key on, got 10.57 at ballast Ign #1/run, 7V at Start side.
Started car and measured voltage direct at batt, and it steadily increased from 12 and change up to over 14 in a matter of 1-2 minutes.
That's all I had time for, hopefully more time the next few days.
Thanks

View attachment 1716401718

Steve, my experience........

I have a couple of industrial battery chargers and it is not uncommon for them to creep up into that range. Especially with an older battery that may be experiencing some sulphation (sp?).

 

[4spdragtop]

Thanks Troy, I was wondering that and this isn't the 1st time I've noticed it.

Steve, my experience........

I have a couple of industrial battery chargers and it is not uncommon for them to creep up into that range. Especially with an older battery that may be experiencing some sulphation (sp?).

 

[Mattax]

There's a selector button on the charger. Yes?
A simple charger is going to control either the current, or the charge voltage.

Think of it this way.
If the charger and the battery are at the same voltage, no electrons are going to move.

To get the battery to charge, it needs to be connected to something with power at higher voltage. The voltage difference is what gets the electrons to move. When they move through the internals of the battery they reverse the chemical reaction and rebuild the charge energy.

We know on most cars the alternator is regulated to provide power from 13.9- 14.9 Volts.
Let just call it 14.5 Volts.
After starting the battery is low and we see on the ammeter that it is getting recharged.
So 14.5 Volts is enough to recharge the battery that might be down to 11.5 Volts.
As the battery charges, its internal voltage comes up. As the voltage comes up, the charge rate comes down. We see that on the ammeter. When the meter shows no charge, the battery is up around 13.4 Volts. This is the surface charge, which is kindof like a buffer.
So when fully charged 1 Volt is not enough difference to get electrons to move.from the alternator through the battery.

If we set a charger to charge at 5 amps, it will increase the voltage as needed to maintain the 5 amps charge rate.
The same is true for any charge rate we select on a manual charger.

There's a photo sequence showing that here
Its why we shouldn't recharge a drained battery with the alternator.
The voltage difference is high and so the charge rate is high.

 

[67Dart273]

Older chargers are not regulated AT ALL and some that claim to be are "poorly."

 

[4spdragtop]

Thanks for the explanation Matt. I called for replacement battery and he told me current battery is 2016, so could be toast? Core charge was $5, so I'll keep old one for now(use in boat??). With new battery hooked up, I was doing some "checks".
There is continuity from battery +ve to the VR case??
Shouldn't there be continuity from the -VE to VR case?
Thanks
Steve

There's a selector button on the charger. Yes?
A simple charger is going to control either the current, or the charge voltage.

Think of it this way.
If the charger and the battery are at the same voltage, no electrons are going to move.

To get the battery to charge, it needs to be connected to something with power at higher voltage. The voltage difference is what gets the electrons to move. When they move through the internals of the battery they reverse the chemical reaction and rebuild the charge energy.

We know on most cars the alternator is regulated to provide power from 13.9- 14.9 Volts.
Let just call it 14.5 Volts.
After starting the battery is low and we see on the ammeter that it is getting recharged.
So 14.5 Volts is enough to recharge the battery that might be down to 11.5 Volts.
As the battery charges, its internal voltage comes up. As the voltage comes up, the charge rate comes down. We see that on the ammeter. When the meter shows no charge, the battery is up around 13.4 Volts. This is the surface charge, which is kindof like a buffer.
So when fully charged 1 Volt is not enough difference to get electrons to move.from the alternator through the battery.

If we set a charger to charge at 5 amps, it will increase the voltage as needed to maintain the 5 amps charge rate.
The same is true for any charge rate we select on a manual charger.

There's a photo sequence showing that here
Its why we shouldn't recharge a drained battery with the alternator.
The voltage difference is high and so the charge rate is high.

 

[4spdragtop]

Lol, i agree Del. Seems like I'm always buying a charger every 5 years.
This one seems decent so far.
I should have daisy chained the 3 batteries thru the off-season and had them on battery tender?

Older chargers are not regulated AT ALL and some that claim to be are "poorly."

 

[Mattax]

Thanks for the explanation Matt. I called for replacement battery and he told me current battery is 2016, so could be toast? Core charge was $5, so I'll keep old one for now(use in boat??). With new battery hooked up, I was doing some "checks".
There is continuity from battery +ve to the VR case??
Shouldn't there be continuity from the -VE to VR case?
Thanks
Steve

I don't know Steve. Not sure what you are doing or testing for. Are you using a powered continuity tester? Measuring ohms with a meter?

The voltage from battery + post to any ground, including the regulator case should be the same as the voltage from the battery negative to positive terminal.

 

[4spdragtop]

There was a intermittent "no crank" when trying to bring out of hibernation. Battery was kept inside thru winter and put on trickle charger(2A).
A couple "odd" clicks under hood when i tried starting. Eventually got it to crank and start after disconnecting battery and charging for a few minutes. Once running i noticed the Autometer Volt meter real close to almost 15V. I checked at battery +ve and -ve and was 14.8(ish). I didn't like that, so i started to dig into the "issue".
I have a decent Voltmeter and am trying to decipher/diagnose.
I just noticed there was continuity between batt +ve and VR case(70 + style)whether key was off or in run. I thought it odd, but I'm thick headed with electrical.
Thanks.

I don't know Steve. Not sure what you are doing or testing for. Are you using a powered continuity tester? Measuring ohms with a meter?

The voltage from battery + post to any ground, including the regulator case should be the same as the voltage from the battery negative to positive terminal.

 

[4spdragtop]

Key on, not running I get 1.1V from batt +ve to IGN #1 at ballast with everything connected.
Checked for voltage drop on -ve side with car running batt -ve to VR case, voltage was in millivolt range.
So issue appears to be a drop from ign #1 circuit? Blue wire and blue with tracer? Which one would be suspect? Of course it's just wrapped/tidied last year lol and gonna be ripping that out....
Thanks
Steve