I have converted by 1950 ford generator to 12v by switching out the generator case for a 12v case and field coils. I polartized the generator by touching the field lead to the batt. lead at the volt. reg. and also by touching the field terminal at the generator with power from the battery. The generator will motor, but doesn't put out current (tested with voltmeter). BUT........ It motors counterclockwise as you face the generator and but the engine rotates clockwise. Is the polarization reverse of what it should be? If so, how can I change it? Thanks for helping.
This is how I used to do it...To polarize: connect the field terminal to the body of the generator (ground) Connect battery plus DIRECTLY (not through the regulator) to the generator B+ terminal BRIEFLY (just a few seconds). It should spin forward.
So a jumper wire from the field terminal to the generator body and a direct power lead from the battery sparking to the armature terminal? Is that correct? Is that for a ford generator? DK
Koolman, I think when you replaced the field coils, they are out of position in the housing and the timing is off. Did you use the old 6v armature?
I used the original 6V armature. Are you saying the field coils are not 'clocked' to the armature correctly? I simply swapped the 6v generator case with a 12v generator case and kept everything from the original 6v generator. I never removed the field coils from the case.
Yes I think that's possibly what's going on- compare the two housings and the field coils are probably wired slightly differently. Polarizing the generator (putting in a slight residual magnetic field in the pole shoes) doesn't have any effect when you're 'motoring' the generator. As an alternative, you could possibly just reverse the field wires (internally in the gen housing) to fix your problem. Let us know how you make out with it. D
I was going to say maybe the brush holders are not in the right position ( off 90 or 180 * out ) or the armature and feild poles are reversed ( if that can happpens as one side I know is grounded internally
well one thign that got me thinking was it motors the wrong way , and if the brushes are out of phase it will motor along with the engine rotation and not make juice ( and we use the generator as a starter motor on the old cub cadets this way ) I was going to mention you do have to use a 12V regulator otherwise the cutoff will not close and not send power to the field .
That is kinda what I was thinking: That the generator motors opposite to the rotation of the engine ( motors counterclockwise and engine rotates clockwise ) which might cancel any voltage output. I have tested the output at the generator eliminating the voltage regulator ( which is a new 12V model ). Nothing but goobly gook changing numbers ( this is a digital voltmeter and possibly it is getting a lot of RF interference from the ignition. ). Also, checked at the battery and no increase in volts. I am I correct is assuming that the polarity of the field coils is irrelevant? OR should I try to change the polarity. BUT how, should I spark the arm. terminal? Thanks for thinking this through with me.
Hi Koolman, If the generator's motoring opposite to your engine rotation, either the brush locations or the field wiring polarity is backwards. I assume you are motoring the generator by connecting the A+F terminals on the generator together and then applying your power to that. By the way, doing this motoring test will also simultaneously polarize the generator... Normally, to polarize a Ford generator, you disconnect the field wire from the regulator and just touch it to the battery terminal a couple times- that's it. Ford gens are known as "B-circuit", and wired differently to other types. I've attached a diagram showing the Ford B-circuit. Also for many older ignitions without RF suppression, a digital voltmeter will be pretty useless as you've experienced already! Use an old moving-coil (needle) type meter. The polarity of the field coils is definitely not irrelevant. It's easy to confuse 'polarizing the fields', with 'polarity of the field coils'. Polarizing is momentarily energizing the field windings, in order to put a slight residual magnetic 'memory' on the iron pole shoes. Reason you need this, is that when you start your car, there is no electric field current applied yet. That slight amount of residual magnetic field comes into play in order for the armature to start to develop current across the brushes, in the correct polarity. After the engine develops some rpm, the field coil is then energized (through the regulator contacts) by using some of the current developed by the armature. A bit like a domino effect. However, if the field coils happen to be wired backwards (incorrect 'polarity of the field coils'), this whole system collapses and the armature will try to develop current in the wrong polarity and nothing works. Usually the cutout contacts in the regulator will start to fry. Hope this helps somewhat?? Don
Don, Thanks for taking the time and for the very lucid explanation! Much appreciated! I did rotate the base plate 180 degrees which rotated the brushes 180 degrees. The generator then motors correctly, clockwise. I then mounted the generator to the engine and tested the output with a analog meter. ( jumper wire between the field terminal and the arm. terminal. Then touching the jumper wire connection and a ground with the voltmeter) I got output readings of about 19V with the engine rpm's around 1000. I still am not getting any battery charging ( checking volts at the battery while engine and generator running around 1000 rpm). I may have fried the VR when the generator was not charging and motoring backwards. BUT, with the 180 degree base plate rotation my base plate is upside down. Funny looking, but also the oiling port is upside down. Is there any harm in running this way? (I could try and find another 12V case or change the field coils. I could turn the generator upside down, drill a fixation hole for the bracket stud etc.) I still am at a lost why the field coils are apparently reversed.
Okay, you're getting progress! Note you won't get much battery charge current while the engine's only doing 1000 rpm. When you're not getting any output with your system, you can determine whether the VR is faulty by doing a few tests: Disconnect the field wire from the VR and start the car. Get it up to about 2000 rpm. Put a voltmeter across the VR BAT terminal and chassis ground. Note the voltage now. Then touch the field wire to the ARM terminal. This will give full field current to the gen and demand max output. The ARM voltage should rise fast and quite a bit, probably to over 15v or so. You would only do this for a max of 20-30 sec, just enough to get a high reading. If this works, the VR regulator portion is bad because it's not giving current to your field. If the test doesn't show these results and things still don't work, the cutout portion could also be the culprit. Test the cutout portion of the VR by doing a similar test- get the engine revving 2000 rpm, and with the F wire connected to the ARM terminal on the reg (full field current), note the voltage on the ARM terminal, then quickly also note the voltage on the BAT terminal. If the ARM voltage is any higher than the voltage on the BAT terminal, the cutout is fried and it is not connecting the generator to your battery and completing the charge circuit. Regarding why the field wiring might be different in the 12v housing, it could just be updated design, since you're using an old armature with a much later housing. They are really built as matched sets and actually we're lucky it works at all! Don
Thanks Don, I will do the regulator tests after I get an oil leak fixed at my oil pressure gauge. ( seems like I get one problem solved and another shows up. ) I will post the results. Dar
because the armature was wound different ( smaller wires and more poles ) or the fields are clocked different to prevent use by another manufacturer or to get around a patent . as for the oil holes check the casting some times I have seen plugs 180* from the ports being used for the oil cups . it will look like a BB was smashed in it thats a lead plug and we would drill them out . but not all generators or motor frames have that .
Some days I'm pretty thick, so this may be a dumb question! Can't you just use the whole 12 volt generator, then you have matching parts that don't have to be upside down and "look funny"?
I wanted to keep my 1950 8cm look, with the intake manifold, generator bracket, fan and I also needed a wide generator pulley to work with my crank pulley and keep consistent with my wide water pump pulleys. I did what was suggested here: http://www.jalopyjournal.com/forum/threads/flathead-generator-conversion.58743/
Just got a 12v core from a 64 galaxy and replace the current case and field coils with it and the generator motors normally (clockwise}. I will have to test the output next.
The generator now is putting out power. I am getting 13.6V at the battery at fast idle. Thanks for everyone's help!! Dar
Way to go Dar, Did you have a good look inside the new gen housing to see what the difference was? Glad you have it working! D
I need to take it apart again, so I will get a look and compare. I will post what I see. Thanks for the help!
It looks like the problem 12V generator case has it's field coil wired opposite of the replacement correct working case field coils. I don't know why. Maybe it was for a pos. ground system, though it was reported to be from a late 50's Ford.
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