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Generator Charging Problem

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  • Generator Charging Problem

    I promised johng I would write up the sequence of how our original voltage regulators work.

    The most important part to check is the current path through the resistors. Here's why...

    When we first turn the key, the voltage regulator is disconnected from the battery. That means the Cutout Relay must be energized strictly by generator power.

    As the generator starts to produce power, the armature (A) feeds the generator's field (F) through normally closed contacts. The coils and resistor (R2) are connected to each other via ground. Without the resistors, current for the cutout relay coil would not have a completed path. Therefore it would never connect the battery to the generator.

    Check this out and give the sequence lots of time to better understand each phase of operation:

    So why is this so important? Troubleshooting a 'dead' voltage regulator is simple if you understand the current paths, especially while the cutout relay is NOT energized.

    Look at the normally closed contacts from the overcurrent and overvoltage relays. If either are dirty or open, the field only gets enough current passing through the top resistor to sustain the cutout relay coil IF it's already closed. It's not enough to initially pull the cutout relay in.

    Battery charging can only happen when the cutout relay is energized. All the generator's power goes through this one contact. The other two control the field.

    I'm sure some of you will have questions. - Dave
    My latest project:
    CLICK HERE to see my custom hydraulic roller 390 FE build.

    "We've got to pause and ask ourselves: How much clean air do we need?"
    --Lee Iacocca

  • #2
    I'll start off with the questions. My son has a '60 with the 30-amp generator and we've been chasing a charging issue for months now. Here's what's been done. Replaced all three wires between the generator and the regulator using 10ga. for the ARM between the regulator and the generator, 12ga. for the field lead between the generator and the regulator, and a black 16ga wire for the ground between the gen and the regulator. All terminals were soldered on and sealed with shrink wrap. Generator has new brushes. Regulator has been replaced three times now. Here's why; First one worked for about a week and the cutout relay stopped pulling in (closing). The second one quit charging after completely burning out the brushes in the generator coming back from a car show. Now I'm on #3. While idling, there's 14.8v at the ARM terminal of the regulator. I have 12.0 at the battery. The GEN light glows dimly at an idle, gets brighter as the engine speed increases (If I momentarily full-field the generator it'll shoot up to 17 volts). Voltage at approx. 2,000 rpm is 15.2v at the ARM terminal. Battery voltage stays right at 12.0. Car currently has a 3-day-old battery in it, and it starts right up. Regulator is a BWD brand R156P. Supposed to be "bulletproof" according to the counter man at O'Reilly. The 1960 factory shop manual diagnostic procedure is not helpful, and is rather confusing on this subject (I don't know anyone that has a 0-100 amp ammeter or a carbon pile rheostat). I know the battery voltage should be around 13.5v if I'm correct. The generator has been polarized a couple times. Obviously I'm missing something, but its about to drive me insane! Any ideas??? Tim


    • #3
      Tim, sounds like you have at least a couple issues. Let's take this one at a time.

      It takes TWO wires to make a circuit, right? We actually have two circuits, one supplied by the battery and the other supplied by the generator.

      Yours are NOT connected together. The GEN light confirms this. How? Your battery feeds the key switch. When turned on, the key switch feeds one side of the GEN bulb. The other end of the GEN bulb connects directly to the armature of your generator at the voltage regulator's ARM terminal. The wiring diagram shows this wire as yellow/black.

      The diagram further shows, when your voltage regulator's cutout relay closes, the ARMATURE is directly connected to your BATTERY terminal's yellow wire. So, the GEN light is connected between your battery and your generator's armature. That means, it will only shine when there is a voltage DIFFERENCE between the two. When you first turn the key, the GEN light shines because the generator is putting out zero but the battery is at 12. Both are separated from each other by the cutout relay contacts. When generator motion starts, the light becomes dimmer until both gen and batt are the same voltage, then the cutout relay contacts close because those resistors on the back of your regulator allow the cutout coil power to flow to ground which closes the contacts. Now, the battery and armature are connected together.

      So far we have not discussed the other wire, your ground wire, because we are on the positive side.

      The generator's case is grounded to the engine and you have a separate ground wire connected to the voltage regulator. The battery is grounded to the engine, but where is the body ground? Are you depending on that generator ground to also serve as the body ground? Don't do it. Like modern cars have, install a short wire from your battery's NEG terminal to the radiator support (or somewhere around there).

      Without these solid grounds, all the power wires in the world will not make your generator charge the battery.

      After grounding is established and you are sure the yellow wire on your regulator is connected to the battery/starter solenoid, take the cover off of the voltage regulator and start the car.

      BTW, your starter solenoid should have all the yellow power wires on the battery side and only ONE fat wire on the starter side. Mis-wiring your solenoid will produce your problem.

      If the voltage regulator resistors are good, the generator should produce enough power to energize the cutout relay and close the contacts. Then, your gen will charge the battery.

      Watch and study my picture in the first post. It's not a simple picture as the cycle takes a long time. - Dave
      My latest project:
      CLICK HERE to see my custom hydraulic roller 390 FE build.

      "We've got to pause and ask ourselves: How much clean air do we need?"
      --Lee Iacocca


      • #4
        Thanks for the reply Dave

        When I got home from work, I did a voltage drop test across the body ground cable, the 8ga. wire between the Rt. side head and the Rt. fender apron, engine running or off, 0.00 volts. Checked voltage drop across both positive and negative battery cables, less than .5v on both while cranking. Checked voltage drop from case of regulator to the body, 0.0v. Disconnected and checked voltage of yellow/black wire from the GEN light circuit at the regulator, had 11.7 volts with key on. Started engine, revved to 2,000 rpm, had 15.8 volts at ARM terminal of regulator, 4.8v at the FLD terminal, 11.7v at BAT terminal. Cutout relay never closed, GEN light obviously still on. I even checked to make sure the bulb was correct, it was (57). I have to be missing something, but this keeps telling me there's something amiss with the regulator. But its currently (no pun intended) on its 3rd one, so I have a hard time believing that's the issue. Possible, but not probable. I find it odd that Ford put that small external ground wire from the generator to the regulator mounting tab, seems redundant but I'm sure the engineers had a good reason for putting it there. 0v drop from the generator ground lug to the regulator base. Just for grins I checked the resistance of the field windings with the field wire disconnected, showed 6.5 ohms. The armature is a new old stock piece from Mac's.

        I normally love a good electrical challenge but this one is kicking me arse! All the other circuits in the car work fine. What should I look at next?
        Thanks for the help, greatly appreciated! Tim


        • #5

          After reassuring myself that I had checked and double-checked everything within the charging system, I removed and opened up the "newest" warranty replacement regulator, and I found the root cause of my issues. At the bottom of the cutout relay's pull in coil, the solder connection where it joins the strap for the contact point had broken away, causing the cutout relay to not close. It looks as if when they assembled it they didn't remove enough shellac from the wire prior to soldering. I cleaned up the solder end of the coil, re-soldered it, started the car and BAM, we were getting 14.5 volts to the battery side of the regulator. I ran outside and repeatedly screamed "I FIXED IT!!!" My neighbors were not amused. My son drove the car about 30 miles yesterday and all is well.
          Dave your animated diagram of the voltage regulator is dead on, but you knew that. Thanks again for your reply!


          • #6
            Don't you just love Foreign made replacement parts.

            John Pizzi - Squarebirds Administrator

            Thunderbird Registry #36223



            • #7
              Well, alright! Glad you found the bad connection. Dad bought land in Middletown, Ohio so I nearly grew up there. Glad to help out, y'all from Ohia.

              Mechanical regulators look bullet proof but all it takes for them to stop working is one skinny little wire that's disconnected or one of those resistors in the back that is broken. Think about it, this invention is brilliant and done with NO solid state. It automatically disconnects your battery from the charging system as soon as the generator stops.

              My thanks go out to you, Timmy. You persevered and used sound troubleshooting techniques to find the fault. You were right to troubleshoot the cutout relay. Many others would have quit. You won this day, for sure.

              I don't have much faith in aftermarket parts until I check them out for myself. I have a 'mom and pop' auto parts store I go to. They ordered a regulator that I waited two days for. After paying fifty bucks, right there on the counter, I pulled out a screwdriver and removed the cover. Sure enough, the contacts didn't mate AT ALL. I showed the salesguy and he got beet red. He said, ' ..want me to order another one?' I said, '**** no, this is pure junk.' He totally understood and promptly refunded my money. Lesson learned: These parts are rarely tried out before they ship.

              BTW, what's wrong with the other voltage regulators? - Dave
              My latest project:
              CLICK HERE to see my custom hydraulic roller 390 FE build.

              "We've got to pause and ask ourselves: How much clean air do we need?"
              --Lee Iacocca


              • #8
                Originally posted by simplyconnected View Post
                ...We actually have two circuits, one supplied by the battery and the other supplied by the generator...
                Originally posted by TimmyT1960 View Post
                ...I find it odd that Ford put that small external ground wire from the generator to the regulator mounting tab, seems redundant but I'm sure the engineers had a good reason for putting it there...
                What happens if the voltage regulator loses (or partially loses) ground?

                Again, we have two power supplies going on. The battery (and it's ground) is one. The generator (and it's ground) is the second. Remember, it takes two wires to complete a path.

                A bad or loose Voltage Regulator ground will never energize the cutout relay so the generator will never connect with the battery. Remember those resistors? They need ground or the regulator simply won't work. Since the generator is the power supply for the voltage regulator, it only makes sense to use a ground wire from the generator because it is in close proximity.

                Whenever I troubleshoot electrical faults, I never let probability sidetrack my methods because anything is possible. I don't listen to, 'well, last time it was...' I simply prove conditions using sound troubleshooting techniques. When there are two or more faults in series, most troubleshooters give up. Not me, that's when my jumper wire comes in coordination with my Fluke.

                BTW Tim, how important is that #57 GEN lamp? - Dave
                My latest project:
                CLICK HERE to see my custom hydraulic roller 390 FE build.

                "We've got to pause and ask ourselves: How much clean air do we need?"
                --Lee Iacocca