Another 8n Charging Issue

[sfrye5853]

Group,
Working with a 49 8n. Removed all the wiring and put it back to a 6 volt system. Put in a new battery, a new voltage regulator (https://just 8n's/8N10505B-Years-1948-50-Voltage-Regulator-8N-Before-263844) a new resistor and mounting block assembly (https://just 8n's/A8NN12250A-Years-1948-50-Resistor-And-Mounting-Block-Assembly) and had an original ford generator rebuilt. Bought all new wiring and wired everything up based on the diagrams in the old manuals. When the tractor is running the ammeter is a 0. When we turn on the lights, it goes negative. With everything new and/or rebuilt, what could my issue be?

 

[JMOR]

Group,
Working with a 49 8n. Removed all the wiring and put it back to a 6 volt system. Put in a new battery, a new voltage regulator (https://just 8n's/8N10505B-Years-1948-50-Voltage-Regulator-8N-Before-263844) a new resistor and mounting block assembly (https://just 8n's/A8NN12250A-Years-1948-50-Resistor-And-Mounting-Block-Assembly) and had an original ford generator rebuilt. Bought all new wiring and wired everything up based on the diagrams in the old manuals. When the tractor is running the ammeter is a 0. When we turn on the lights, it goes negative. With everything new and/or rebuilt, what could my issue be?

Iron pole pieces in gen need residual magnetism in order to initiate generation. It gets this from polarizing the generator. For your gen, this is done in about one second by shorting Battery to Armature.

 

[Factotum]

I find that my 8n doesn't charge until the rpm is over 1100 or so.

 

[DWF]

I find that my 8n doesn't charge until the rpm is over 1100 or so.

Do you have an alternator, if so quite a few alternators need a little speed to excite them.
DWF

 

[Factotum]

No. It's a generator, I think they work the same? At least low rpm don't charge very well. I only mentioned it since the op may have been idling and not seeing a charge.

 

[sfrye5853]

No. It's a generator, I think they work the same? At least low rpm don't charge very well. I only mentioned it since the op may have been idling and not seeing a charge.

Thanks, after doing the above jumper wire technique, we drove it around the block (in a neighborhood lol), never showed a charge.

 

[Factotum]

Something I did when it didn't want to charge, I cleaned the contacts in the voltage regulator with some 800 grit. Just a couple of passes to make sure they were clean. Now, I didn't get into any real testing at the time, I figured it was just as easy to quickly try and clean the contacts and see what happens. Shorting bat to arm when running caused mine to charge immediately. Since then it'll charge at 1100 rpm, so I haven't pursued it any further.

 

[Janicholson]

Iron pole pieces in gen need residual magnetism in order to initiate generation. It gets this from polarizing the generator. For your gen, this is done in about one second by shorting Battery to Armature.

If the generator is a B circuit (probably not) the field is polarized by removing the wire from the Field terminal on the regulator, and jumping 12 volts from Bat to the F terminal on the gen. (not the regulator terminal. Jim

 

[docmirror]

Are you certain, positive, 100% that you hooked up the ammeter correctly? An ammeter hooked up backwards will show a charge as a discharge as the current is flowing in opposite direction.

Charge your batt fully. Take the charger off, wait 2 min and measure the resting voltage of your battery. Record that reading, about 6.3 or a bit more volts. Start the engine, and run it up to 1200 RPM. Now measure the voltage of the battery. Is showing 7.4 or greater volts? If yes, your ammeter is wired backwards, swap the two wires on the ammeter. If it is below 6.3, you are not charging.

I've had marginal luck with new V Regulators. With the tractor running at 1200, measure the voltage on each of the three legs on the V Reg. Report back here.

 

[JMOR]

Thanks, after doing the above jumper wire technique, we drove it around the block (in a neighborhood lol), never showed a charge.

As a generator test, you can temporarily bypass the VR with a jumper from BATT to ARM while running and if still no charge, add a second jumper from Field to Ground. At this point the VR is doing nothing and Arm is connected to battery and Field is seeing full voltage/current.

 

[Ozlander]

Now you know why it had an alternator on it.
Went thru the same thing on my Ford 860.

 

[FWB in SK]

What JMOR said will tel you if it is a Gen or Regulator problem..