Generator charging rate--part 2

To r4etired,Bob M. and Jim N. Thanks for all your advise. Found the resistor in the electrical box damaged with the wire broken and also found the 3rd brush in the generator loose and in contact with the output brush. Corrected that, and had to fabricate a resistor because none available in our little town. Would appreciate advise on where to order an original type, or suggestions about substituting another style. Thanks.

You're making good progress Dr!

I doubt a an original replacement resistor is available. (The usual fix for a busted resistor was to replace the cutout with a voltage regulator and eliminate the resistor entirely).

However any resistor with a value of 5 - 10 ohms or so and rated for 5 watts or more will work. If there's an amateur radio operator or electronics enthusiast in town pay him a visit - guarantee he'll have something in his "junk box" that will work.

Or you can substitute a small 6 or 12 volt lamp with a cold resistance in the 5 - 10 ohm range. A #194 side marker/instrument panel bulb is around is 5 ohms and should work.

I think you are doing well!
The resistance value is in the 5 ohm area. I believe a 50 watt resistor will be able to handle the heat. I think bob lrft off a zero. JimN

I think you are doing well!
The resistance value is in the 5 ohm area. I believe a 50 watt resistor will be able to handle the heat. I think bob lrft off a zero. JimN

Yo Bob n Jim, where you guys coming up with that "5 ohm" low charge external field resistance value??????????????? Seems to me like 3 ohms is more in line (for a 6 volt system at least) and 5 may be too much. Lets chew on this some, you guys got any known good LHBD switches laying AROUND AND A GOOD OHM METER LOL

ALSO is this a 6 or 12 volt system??? which makes a difference (5 ohms sounds more like it if a 12 volt system)

While there is a difference in genny field current, I see many of the older delcos (maybe those were all 6 volt units??) that draw 2 amps of field current, That means their fields total 3 ohms sooooooooo if you added another 3 in series at the LHBD switch the current is one half for LOW charge SOUNDS REASONABLE RIGHT????? i.e 5 ohms is toooooooo much

NOW if its a 12 volt genny and it still draws 2 amps of field current now then we have 6 ohms of field resistance so the addition of an additional 5 sounds about correct

SOOOOOOOOOOOOO I reckon Ima saying the resistor would be around 2 to 3 ohms if on a 6 volt tractor but 4 to 6 (You guys recommendation) on a 12

THIS A 6 OR 12 VOLT AND IS IT A 2 OR 3 BRUSH GENNY???????????

Sorry if I just missed that info

Yall Please correct my errors, PS you wont get any cherry lol

John T

John T---Thanks for the input. It is a 6 volt system with a 3 brush generator.

Thanks Doc, Lets see what my friend Bob n the Jimster have to say butttttttttttt if its a 6 volt with a 3 brush genny (as I sorta expected) IMA THINKIN 3 0hms is plenty of external (on the LHBD switch) resistance but with 5 ohms she wouldnt charge much if any. Nowwwwwwww dont get any Bright/Dim resistor confused with the gennys Low Charge Field resistor, the Bobster has pics of which is which I think n seems like the flat wire wound one is the bright/dim n the round is the field resitor THATS EITHER CORRECT OR REVERSED LOL Bob or Jim who are much more current on IHC then myself will know fer sure I bet

John T

You are correct. My thinking was based on the 20 or so amps being pushed in the first go around when the third brush was hitting the main Input (hot) brush. Now that that is operational, the three ohms # is good. I have used resistors out of heater blower motor speed control packs (from cars) to replace them.
But I never checked the actual resistance. Oh well. They do need to be able to handle 20 watts or so of dissipation to be realistic. the sealed nature of the box they are in prevents much air cooling. I think the light resistor (on those I"v been into) are open wound spirals
The Field resistor is the flat wound unit. There are different designs I think. JimN

Hey John T - you are correct about the two resistors' configuration!

The field resistor is a flat wound affair wound onto a flat, bakelite(?) bobbin/terminal assembly.

The headlight dimmer OTOH is a half-dozen or so loops of heavier wire in a self-supporting coil configuration. Further, from the factory the dimmer coil was originally wrapped in (gasp!) asbestos insulation - which is usually long gone 60 years later.

Regarding field resistance values and wattages I know a #194 lamp (4 - 5 ohms) will work as a substitute resistor because in a jam I tried it once! It'll cause the generator to max out at 3 - 4 amps - enough to fire the ignition and leave an amp or two left over to float charge the battery (ideal for long runs in hot weather).

...Bob M

To All My Tutors: Could not find a resistor in the town, so took one off the back of of an old voltage regulator--measured 4.8 ohms-- installed it and everything works--sort of--. When the knob is turned to H, I get about 4 amps charge and when on L --14 -15 amps. Obviously, a switched wire somewhere, but I can live with what I've got. Thanks again for all your help.

You are welcome. The fine times John T Bob M myself and many others have on this forum are justifiable on their own merit. Thanks for the opportunity. JimN

No point arguing over something that can be looked up:
Dimmer resistor 5 ohms.
Field resistor 2.8 ohms.

By the way, the original style cut-outs have a resistor connected to the F terminal. You can use it for low charge by adding a jumper from the generator F to the cut-out F and leaving the resistor off of the switch.