Posted: Sun Jun 17, 2018 8:09 pm Post subject: Polarizing the electrical system. - need help
I need some help understanding how to polarize the electrical system on my jeep. I can't find anything in the military manuals I have. I've done some research on the web but much of information was contradictory and now I'm more confused than before I started.
Here are some details on my set up. My jeep is a 1952 M38 Frankenjeep. The jeep has not run since 1980. I'm almost done a complete rebuild of all the major systems. Here is what I have for the electrical system:
The system is 12 volt using a single battery in the cowl battery box.
The jeep has a new CJ3A wiring harness from Walcks.
I have not been able to identify who made the generator. It was six volt but I had it rebuilt to 12 volt.
I believe that the starter may be an AC Delco unit. It was also rebuilt to 12 volt. It has a solenoid and the jeep has a key start.
The voltage regulator is from Walcks. It is described as a 12 volt regulator for jeeps from 1957 to 1966.
So my questions are:
1. How do I polarize the system?
2. I currently have the battery installed and grounded but the the positive cable is not attached to the starter or battery. Do I need to install the positive cable before the system is polarized or should I leave it off until the system is polarized?
3. Below are two pictures, one of the generator and one of the regulator. The regulator did not have a ground terminal, just Field, Armature, and Battery terminals. I attached the generator ground wire to the regulator cover screw (as seen in the picture) is this correct?
4. Does the system need to be re-polarized fi the battery is disconnected?
Thanks as always for your help. I'm getting close to the end and I don't want to fry my parts by messing this up. Marty
All DC electrical systems powered by DC generators will often require polarization. This can become needed during a component replacement/repair or after long storage periods resulting in dead batteries.
You must know exactly which type DC generator based system you have. They came in two forms or systems :
A System: Externally Grounded Field Generator.
B System Internally Grounded Field Generator.
You must know which you have because they are polarized differently.
Here's a quote from the old Vernco web page:
Quote:
All of the generator manufacturers made two types, with the field either internally or externally grounded. This is a bit confusing, as neither type operates any better than the other.
However, it is also critical that the voltage regulator be the matching type.
The stock generator used by Willys was the "A" type, with an externally grounded field coil. Remember, I don't know if your generator is the stock unit or not, and have good reason to suspect it is not. The other type, a "B" type, has an internally grounded field coil and uses a different method for polarization.
Cross referencing the part number on the generator may not mean anything, as it could have been converted from an A to B type, or visa versa. With an ohmmeter, it is easy to determine whether you have an A or B type generator:
First disconnect the battery. Disconnect the field connection on the generator. (It is the
smaller of the two insulated terminals) Remove the cover over the generator brushes for access. Zero out your trusty ohmmeter and connect it between the field terminal (on the generator) and the generator frame. You should see maybe 3 or 4 ohms, which is the field coil. Now pull back on one of the brushes, it doesn't matter which one, so that is doesn't touch the commutator. You can usually see the heavy flexible copper wire used
on them. If your meter still reads the same, you have a "B" circuit. If you lose that continuity, you have an "A" circuit just like one on my CJ2A.
It is very important that you take the couple of minutes to determine whether you have an A or B type generator before proceeding. The above test with an ohmmeter will only take a few minutes. Hook the battery up again for the generator polarization.
Here is what an old textbook of mine has to say about polarizing the "A" type circuit: "With all the leads connected, momentarily connect a jumper wire between the ARM and BAT terminals of the regulator." You could also accomplish the exact same thing by momentarily connecting a jumper between the battery's (+) post and the armature
connection right on the generator. This beats trying to read those terminal labels buried at the bottom of the regulator. Make the final connection at the generator so the spark is away from any explosive hydrogen gas vented by the battery. Naturally don't do this in the presence of any gasoline vapors, either.
The B circuit is polarized just a bit differently. Remove the Field ("F") wire from the regulator. Momentarily touch the "F" wire to the battery ("B") terminal on the regulator.
Reconnect the "F" wire to the regulator.
Wes, thank you for that information. I have the cover off the Generator. The instructions say to "Now pull back on one of the brushes". I'm afraid I'm not quite sure how to do this. I can clearly see a spring on the brush that I can pull back towards me but it does not seem to move the brush off the commutator. I just wanted to check in for some additional information on how to complete this particular task before I proceed. Thanks, Marty.
The spring only maintains pressure against the brush. The brush is not attached to it. You must find the electrical lead that is attached to the brush and pull on it.
Finding out which generator you have is only half the battle.
The wrong regulator will damage the generator.
Once you determine weather your generator is a circuit A or B then you must research the regulator's part number to determine which generator it is used with. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Wes, I pulled the generator today and completed the ohm tests. My generator is an "A" circuit generator. My voltage regulator is also an "A" circuit regulator so I should be good to go. Many thanks for posting those detailed instructions. It took me a little while to figure out how to lift the brush but it turned out to be very simple once I got a close look in good light. Thanks again, Marty.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
Forum FAQ
Search
Usergroups
Profile
Log in to check your private messages
Log in
