Why am I getting 22-30 volts?

Charging, starting, lighting, gauges, HVAC

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GregoYatzee
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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Fri Oct 14, 2016 11:37 am

So, today I talked to a guy at a used tire/scrapping shop... he suggested disconnecting the alternator. Hadn't thought of that...sadly...

Battery and field lead off alternator, truck started and ran smoother than it ever has. alt output read about 2 volts. Connected the field wire and alt output started @ 55 volts and climbed to 70 volts before I shut it off after a minute or so. Ran full field test with vr bypassed, same voltage output from the alternator. Is it possible that the pulley is too small? (grasping at straws)

Recap/pondering... At this point, I believe that the alternator is totally isolated from the system as far as any other possible short is concerned. Solid ground, battery wire is disconnected (truck running entirely on battery), new field wire... which was disconnected from the truck while jumped for field test. In the morning, I will take both the new and old alternator to be bench tested. I am still curious about 3 alternators having the same problem.

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sargentrs
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Re: Why am I getting 22-30 volts?

Postby sargentrs » Fri Oct 14, 2016 7:26 pm

Maybe it's time to just bite the bullet and bypass the VR altogether with a 1-wire alternator system. http://www.speedwaymotors.com/Tuff-Stuf ... ,9283.html Running one on my Fairlane right now with no issues, just not this particular one.
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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Sun Oct 16, 2016 11:11 am

I found and repaired a short in bed side markers.

With ignition to on, another short runs through the system. Is the wire from distributor to coil "-" supposed to be grounded? When I unplug wire to "+" side of coil, short goes away. I had to pull new distributor, point fell apart... Junk. I put old distributors back on and wonder if the insulator in it is bad.

The reason I keep skipping on rebuilding charging system is that all its components test out. Don't wanna spend time and money with no evidence pointing that direction...though I have essentially rebuilt it already.

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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Sun Oct 16, 2016 11:54 am

Used this process from http://www.gasenginemagazine.com/gas-en ... geContent3

"Use your voltmeter to check for a short to ground between the battery and the points. Block the points open with a small piece of wood and put one probe on the appropriate battery terminal and the other probe on the point itself. Just make sure that you have your polarities straight. With the points blocked open one will be positive, the other negative. If the meter doesn't show any voltage when the probe is on the "spring clip," you may have a bad insulating washer at the distributor, which would let electricity go to ground through the block before going to the points. Test for continuity between the block and the negative coil terminal to confirm this theory. Test for continuity between the block and the stationary point attached to the distributor plate."

With points open, I get 12.5v on fixed and 0.4v on spring. The fixed point has continuity with the block. When points are closed, there is continuity to the negative coil terminal. When open, no continuity. I either have to special order distributor or spend more and eliminate points.

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Re: Why am I getting 22-30 volts?

Postby dv7508 » Mon Oct 17, 2016 10:38 pm

The yellow wire that splits from the black 8-10 gauge wire is the sense wire going to the voltage regulator. In the video, when you crank the engine and your multi meter + probe is in the fuse holder, you get high voltage, due to the circuit being open. The yellow wire is supposed to sense and basically tells the regulator to adjust field current based on load conditions, state of charge, etc. An alternator MUST have the battery in the circuit or it will not function properly, ie. overcharge. A generator does not require a battery. An open or much resistance in either the "hot" wire or the yellow wire will result in your problem. Ford never used a 30a fuse, but rather a fuse link. In your case, delete the fuse holder. Orange wire (fld) goes to fld term on reg. Green wire goes i term of reg and is run thru indicator light or a resistor, but CAN be 12v switched. White w/ black stripe goes from sta on alt to S on reg, it's only function is to turn off indicator light (or electric choke) and is not needed for charging. Yellow wire goes from bat + to A term of reg. Do all this, and it will charge, assuming reg and alt are grounded. Or, visit your local starter shop, not the box parts stores, and take your alt and ask for a F7078 1 wire regulator. They will bolt it to the back of your alt, charge you $50, and all you have to do is run 1 "hot" wire to the battery. Problem solved. If you deside on the 3 G conversion, see the thread on fordification, then ask your parts store for an Alternator for a 1997 ford Taurus 3.0. Bolts right on. These can also be fitted with a special 1 wire regulator for simplicity.


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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Tue Oct 18, 2016 10:27 am

dv7508 wrote:The yellow wire that splits from the black 8-10 gauge wire is the sense wire going to the voltage regulator. In the video, when you crank the engine and your multi meter + probe is in the fuse holder, you get high voltage, due to the circuit being open. The yellow wire is supposed to sense and basically tells the regulator to adjust field current based on load conditions, state of charge, etc. An alternator MUST have the battery in the circuit or it will not function properly, ie. overcharge. A generator does not require a battery. An open or much resistance in either the "hot" wire or the yellow wire will result in your problem. Ford never used a 30a fuse, but rather a fuse link. In your case, delete the fuse holder. Orange wire (fld) goes to fld term on reg. Green wire goes i term of reg and is run thru indicator light or a resistor, but CAN be 12v switched. White w/ black stripe goes from sta on alt to S on reg, it's only function is to turn off indicator light (or electric choke) and is not needed for charging. Yellow wire goes from bat + to A term of reg. Do all this, and it will charge, assuming reg and alt are grounded. Or, visit your local starter shop, not the box parts stores, and take your alt and ask for a F7078 1 wire regulator. They will bolt it to the back of your alt, charge you $50, and all you have to do is run 1 "hot" wire to the battery. Problem solved. If you deside on the 3 G conversion, see the thread on fordification, then ask your parts store for an Alternator for a 1997 ford Taurus 3.0. Bolts right on. These can also be fitted with a special 1 wire regulator for simplicity.


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Thank you, Ira.
In short, eliminate ammeter gauge and rewire for the dummy light? If so, any special light, or can I just wire in a 12 volt socket? Ammeter leads on the cluster are gone (burned out). My plan was to eliminate the ribbon and hard wire everything.

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Re: Why am I getting 22-30 volts?

Postby dv7508 » Tue Oct 18, 2016 8:52 pm

Any 12v light would do, I would not use an 1157 bulb, but any small 12v bulb would be appropriate. The OEM ammeter uses a shunt coil, and was marginal even when new. A true indication of charge would be a watt meter (Volt x Amp=watt), but none exist. Amperage is only relevant if you know voltage as well. Idiot light is pretty fool-proof. Even the 1 wire setups have a provision for a light if desired.

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Re: Why am I getting 22-30 volts?

Postby Ranchero50 » Wed Oct 19, 2016 7:05 am

Ditto. This is why I ended up with a voltmeter in my cluster. At least it gives a true reading of the battery.
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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Sat Oct 22, 2016 10:51 am

Before I dig into rewiring, I want to eliminate all possibility of shorts. The black/yellow wire (37) (which feeds the ignition, light switch and the fuse box) has continuity to ground. Light switch and fuse box are unplugged and test OK. At ignition, the purple and red/blue both have continuity to ground. The purple goes straight to the dual brake warning switch. The red/blue tests good and goes straight to the S term on ignition solenoid. I have seen solenoid tests describing that the S term should test continuity to ground. Is this correct? If so, how does it not short the system as it is tied into the main supply and is carrying it through the ignition? When I turn ignition to run, the continuity to ground continues to the corresponding wires. I have looked through this post: viewtopic.php?f=8&t=68376&p=726168#p726168 and speculate that there may be a problem with the switch. However, when I unplug this at the firewall, that short is isolated.

For wiring, I am looking at the attached diagram. Will it function properly if I do not wire a light, leaving the I term empty? Also, does the A connect to the battery term of solenoid?
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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Mon Jun 19, 2017 5:33 pm

Been a while, back at the truck again. I installed a one wire (GM) alternator. Nothing is wired except the battery, solenoid, starter and start/run coil wires. Started the truck WITHOUT connecting wire to alternator. Truck runs fine off the battery. The alternator is producing 50 volts at idle. Voltage drops to the 30s if I increase idle. Is it possible that the pulley is too small? Every alternator I have used has the same sized pulley.

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Re: Why am I getting 22-30 volts?

Postby Ranchero50 » Mon Jun 19, 2017 5:49 pm

No, hook the alternator up to the battery so the battery knows how hard to charge.
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Re: Why am I getting 22-30 volts?

Postby GregoYatzee » Mon Jun 19, 2017 7:38 pm

13.3 volts..... :thup:
Now to start wiring everything else back one at a time to make sure all is well.
Thank you. Will update when finished.

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Re: Why am I getting 22-30 volts?

Postby 69Ford » Tue Jun 20, 2017 3:00 pm

If you have two 12Volt hot wire shorted together it will double the voltage to 24Volts inspect the wiring for two hot wire's connected together.
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Re: Why am I getting 22-30 volts?

Postby MadMike » Fri Aug 18, 2017 2:52 am

69Ford wrote:If you have two 12Volt hot wire shorted together it will double the voltage to 24Volts inspect the wiring for two hot wire's connected together.


This is not how voltage in a single power source system works.
Single battery, only 12VDC possible. You cannot create 24V or 240V by increasing the number of circuits tied together.
Two batteries, normally done in parallel to improve Amperage and capacity of the system would still be 12VDC.
Done in series they would create 24VDC but amperage would stay the same as a single 12VDC battery. One would use two of the same size/age/capacity batteries for this.

Now, one could make an elaborate, PITA, system where you could possibly create two separate systems(vehicle and house) and crossing the wires may double the voltage, however it would be highly unlikely that anyone would spend the time/money/resources to play mad scientist on their old Bumpside.

Whenever voltage is over 15VDC, there is usually something wrong with the regulator of the alternator.
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