exciting the alternator on a 1989 john deere 210c backhoe

The alternator will be spinning once the engine is running. The accessory position is there so you can listen to the radio with the engine off, you'll defeat that by hooking the alternator there, that's the only reason not to do it that way. Acc is also on with IGN when the engine is running.

Delmer,
I knew what the acc.position was for,but i did not know that it was active with the key in the on position. So just to be sure I'm getting this right, you're saying if i hook any 12v load to the acc.side of the ignition switch it will have power when the switch is on acc.and also when on the run side? I can't believe that I never knew that! Thank you, for clearing that up.I'm not saying that I didn't believe Repowerguy, but i was more than a little skeptical. LoL
thanks again, Lee

Hey,if you know anything about the hydraulic system on the 210c give my most recent post a look.

Yes sir, doesn't your radio work when the key is in Run?

Can you post a couple pictures of the setup and the end of the hose that came loose? The thing that I've seen blow hoses is air in the system, it gets released under some residual pressure and that is enough to blow a hose loose when it could easily handle the hydraulic flow without the surge from the sudden air pressure release.

The accessory term is hot when the key is on. Think of your truck, things like the radio are powered off the accessory side of the switch. If you power the excite term on the alternator from this, it will be separate from the ignition circuit but still powered up when the engine is running.
This is providing the switch has a accessory terminal on it of course.

Delmer, it sure does.
I think from reading Repowerguy and your messages,i was assuming that the acc.and the run position circuits were one and the same. When I thought about it i knew that they couldn't be. Because when the key is in the run position it would be possible for both circuits to be energized as one. But with the key in the acc. Position you wouldn't want your warning lights, gauges, etc.and the radio to be on at the same time. Therefor i was thinking two separate circuits,not thinking that in one position they both are energized and in the other only one.

repowerguy said:

The accessory term is hot when the key is on. Think of your truck, things like the radio are powered off the accessory side of the switch. If you power the excite term on the alternator from this, it will be separate from the ignition circuit but still powered up when the engine is running.
This is providing the switch has a accessory terminal on it of course.

Click to expand...

Repowerguy,
I get it now,if you read my response to Delmer, i explained my thinking, or lack of. I guess I was responding to him when you posted.
Thanks for your help, Lee

Repowerguy,
correct me if I'm wrong, but if the acc.circuit is energized while the switch is in the run position that means the excite circuit would be energized the whole time the machine is running correct? I was under the impression that the excite circuit should only be energized for a brief moment, until the alternator can make its own power.

As far as I know the alternator will be fine with power to the excite term while running. If that makes you nervous, you can run it in series with a dash mounted light, a idiot light if you will.
I'm sorry if it seemed I was piling on, after I made my response at 5:00 I got all the other posts from you and Delmer. A glitch in the forum software maybe?

Don't worry about it,i didn't think anything of it.
I'm on here because I want the advice of people who know a great deal more than me about these machines and their problems, i appreciate all of the responses .

Lee Timmons said:

Question,
the 560 ohm resistor that hookedondiesel talks about,is this the same as the diode that WRWtexan spoke of? If so where can I buy one? Wire it directly into the wire i have running from the alternator to the starter selonoid correct? I figure that i might as well put one in for safeties sake, being i don't know how long it will take to fix it right.
Thanks again

Click to expand...

The resistor is not the same. If your tractor is wired with the regulator through the dash, the power wire goes through the "gen" light bulb to bring the charging system online. If the bulb burns out, then the power cannot go through the bulb, so it won't charge. So they put a resistor around the bulb with a high enough value to not affect the bulb lighting up, but low enough value that if the bulb burns out, the resistor can still pass current through to bring the charging system online. You don't have to worry about any of this if you are going to rig your own wire.

A diode is just a electrical check valve, much a like a hydraulic check valve. It can be useful to let the excite signal go to the alternator, but not let the voltage from the alternator come back to the solenoid and cause problems. Radio shack usually sells these.

Lee Timmons said:

I was under the impression that the excite circuit should only be energized for a brief moment, until the alternator can make its own power.

Click to expand...

The excite only NEEDS to be energized briefly. But on nearly every machine ever built, it is energized from the ignition switch, mostly through an idiot light as described.

The only reason not to run it off ACC is that the battery will drain faster if you run the radio with the engine off.

The diode is for hooking your own line to the ignition or start positions, to keep the alternator from feeding power back and running the starter or keeping the engine running when you shut off the key.

All of you talking about the 'excite' wiring; is this the same wire as going from the ignition switch, thru a voltage regulator and then into the brushes in the alternator?

I've driven at least 100 different cars and trucks, and none of them with an alternator ever had any pushbutton to get it charging. It does that automatically when the 60 watts of power start flowing thru the rotor. It's about a 5 amp draw thru the rotor. Most alternators have a field terminal; that's the rotor windings, output off the stator, and the bulb circuit terminal.

The charge light circuit is power from the ignition switch into the bulb and it grounds in the stator, which is the output of the alternator.
When the alternator starts charging, there is 12 volts of power coming back up the wire to the bulb. With 12 volts on both sides of the bulb, no current flow and the bulb goes out.

This is what Franklin2 was talking about, but didn't include exactly how the bulb has the same voltage at both ends.

I've read about the GM single wire deal, those have to be turning 2K rpms? to charge.

I've heard about exciting a generator that has a permanent magnet instead of an electro magnet as in an alternator. But alternators don't need that.

Lee Timmons said:

Question,
the 560 ohm resistor that hookedondiesel talks about,is this the same as the diode that WRWtexan spoke of? If so where can I buy one? Wire it directly into the wire i have running from the alternator to the starter selonoid correct? I figure that i might as well put one in for safeties sake, being i don't know how long it will take to fix it right.
Thanks again

Click to expand...

The resistor is placed "across the bulb connection's, in the underside of the bulb socket.
It's a safety should the bulb burn out. I don't believe there is a need for a diode as you have an internal regulator in your alt that already takes care of this.
The "eciter" wire needs to be only momentarily, not constant, this is where you may run into feedback if you hook it up to "run" or "acc". It should be ran from the "start" circuit, and only get juice to excite momentarily.

El Hombre said:

All of you talking about the 'excite' wiring; is this the same wire as going from the ignition switch, thru a voltage regulator and then into the brushes in the alternator?

Click to expand...

The excite wire is just the Rube Goldberg way of getting it to charge. You need a magnetic field cut by another set of windings to generate power. Exciting the rotor is a way to start this magnetic field, and then by nature it stays magnetic until the rotor is stopped. The ignition switch power to the regulator is the normal way most things are wired from the factory.

hookedondiesel said:

The "eciter" wire needs to be only momentarily, not constant, this is where you may run into feedback if you hook it up to "run" or "acc". It should be ran from the "start" circuit, and only get juice to excite momentarily.

Click to expand...

I disagree. I CAN be run momentarily and work, but it is usually switched with the ignition switch.

Really, it shouldn't take two pages to Jethro an alternator, he had it working in post #15, and he doesn't need to understand what's going on to fix the original wiring, just needs a manual.

El Hombre, I disagree slightly with you to. The bulb circuit IS the excite line that goes to the field to start the charging. Once the alternator is charging the current draw stops and the light goes out. The other line is usually a remote voltage sense line that goes to a relay or fuse panel away from the battery, so that most of the electrical system will be in the right voltage range, even if the alternator has to put out 16V to keep the headlights, wipers, and fan feeds at 14V. For jethro'd farm wiring, that wire can go directly to the battery terminal on the alternator. There can also be a "W" terminal that is one phase of the AC output that is for driving a tachometer from the varying frequency.

The resistor/bulb serves the same purpose as the diode. To keep the engine from running on when you turn off the key switch.

The exciter terminal will keep putting out +14V while the engine still spins, but when it gets back through the resistor it will have dropped to negligible voltage.

If there is no diode or resistor, the voltage from the exciter terminal can easily supply enough power to keep the fuel solenoid on.