no charge at idle

[dick lyons]

hi guys. what can I do to get my one wire alt. to charge at idle r.p.m. its good good once its excited. 6volts with wide belt pully on a eac engine. internally regulated. thanks. dick.

[dick lyons]

thanks for the reply, prof., I guess that is one way to do it, but I was hoping someone on the barn has done it electricly.

[Jack E/NJ]

dick lyons>>>what can I do to get my one wire alt. to charge at idle r.p.m. its good good once its excited>>>

That's the nature of most 1-wire alternators. Just rev your engine a bit on first starting to self-excite the alternator. Then it should charge fine at idle. Rev on every start.

Jack E/NJ

[CT AV8]

I have a 12v one wire on our AV8 and you need to rev it up to about 1,500 rpm to excite it. It should charge at idle after you do that. Also keep in mind, that one wire goes to the battery terminal on the solenoid (or to the battery itself), so it's always hot and since the alt is grounded, it will eventually discharge the battery if left unattended. You could wire it through your ignition switch but I wouldn't advise it since that's your charging wire to the batt and carries high amperage. I used a 10 ga on a 12v system. You will need something heavier on a 6 volt. That could be part of the no charge problem also.

[41LjH]

Generators generally won't charge much (or at all) at idle. Suppliers sell one wire alternators that are reworked to charge right off idle. Even they won't charge below about 1,000 PRM, but that's better than 1,500 for a normal generator. If you aren't highway driving and have a generator or a one wire alternator that hasn't been reworked then watch the AMP meter

[Marv]

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Originally Posted by dick lyons

hi guys. what can I do to get my one wire alt. to charge at idle r.p.m. its good good once its excited. 6volts with wide belt pully on a eac engine. internally regulated. thanks. dick.

You could change the alternater pulley. Go to a smaller one.

[dick lyons]

marv. it already has small pulley. 41, I guess I will live with it. av8,it doesn't charge at idle after rev up. also, I have a battery cut off switch I always use at shut down. jack, refer to reply to av8. guys, thanks for your replys. this is what the barn is all about. any one else want to help, please do. dick in tiny Delaware.

[Bruce Lancaster]

A fairly cheap solution is to change the regulator in there to a normal one...the jump to 2 wires instead of one is not a big deal, and then it will charge like a modern alternator. The need for higher revs to engage the thing is tied to the single wire regulator.

[Ed Pitts]

I use a 3 wire alternator on my 36 as Bruce has suggested. You just put a diode in line with the white wire that goes to the ignition switch. This is the exciter wire and the current only goes to the alternator. This setup allows the alternator to work as it normally does in a late model car. Ed

[dick lyons]

bruce and ed. I suppose the thing for me to do is take the alt. to a shop and explaine what I want. I don't know enough about wireing . bruce, you say 2 wires and ed says 3. sorry, but I don't get it. maybe a diagram from you, ed?? thanks, dick.

[Ed Pitts]

Dick, sent you an email with a further discussion. Here are a couple of pic of a 39 engine on the engine stand that shows the alternator wiring a little better. Ed

[Jack E/NJ]

ck lyons>>>but I don't get it.>>>>

Your best bet is if you can find an alternator shop that can replace the 1-wire internal regulator with a 3-wire internal regulator.

If you want to run a 3 wire regulator as a 1 wire all you do is run a pigtail wire from the #2 sensor terminal directly to the battery output terminal. The #1 exciter terminal is left open (you don't have these 2 terminals on your existing regulator). As you already know, without an exciter terminal, you sometimes must rev the engine a bit to get it to start charging from residual magnetism in the alternator.

For a 2-wire setup, again run a pigtail from #2 to the battery output terminal. The #1 terminal is then connected to the ignition switch thru a bulb idiot light and/or resistor in series.

For a 3-wire setup, run a wire from #2 to some remote circuit location to sense voltage at that point. The #1 terminal is connected to the ignition switch like the 2-wire setup. The 3-wire is the best setup to keep battery properly charged and is preferred over a 1-wire only alternator setup.

As for your existing 1 wire not charging at idle with a smaller pulley after excitation , I think this indicates a problem with either the alternator coils or its internal regulator.

BTW, if the alternator does drain the battery when not in use, there is a problem with it's internal diodes.

Jack E/NJ

[Bruce Lancaster]

On the 2-3...Jack knows far more about it than I do! But what I learned matches what he says: I was converting a GM car from the early external reg alternator to the '70's type. Manuals had the 3 wire circuit, then I went shopping at the junkyard for terminal shells to refill with new brass so I could build a nice original looking harness, and I discovered that GM used the 2 wire circuit as described by Jack on some of the later cars using that common alternator. Connection was made right on the alt, with the extra wire straight from its terminal right over to the big bat connection.
2-3 wire setup is simple enough that I don't see any reason to put up with the single... that kludge seems to take away about half the benefits of the alternator!

[Ed Pitts]

The plug in connector that contains the red and white wires (shown in the second pic in Post #10) can be purchased from NAPA. Part # VRC148 at $4.49
The diode can be purchased at Radio Shack.

[Jack E/NJ]

Ed Pitts>>>You just put a diode in line with the white wire that goes to the ignition switch.>>>

Hi Ed. Why are you using a diode instead of or in addition to a bulb and/or resistor to the ignition switch for excitation? Thanks. Jack E/NJ

[Ed Pitts]

Jack, the diode is a one way switch that allows the current to flow in only one direction and you want that to be from the ignition switch to the alternator.

[Jack E/NJ]

Hi again Ed. From your pictures, it seems you are using a GM SI series type of alternator or clone. I don't believe a diode is specified in this application for a 3 wire setup. However, a 10-20 ohm resistor and/or idiot bulb is specified in order to limit the excitation field current. Without this resistance, your diode won't limit this current other than by virtue of a small ~0.5 volt drop in its forward-biased state. Your internal regulator should not allow voltage to exceed the alternator output voltage at its exciter terminal to the extent your diode is actually in a reverse-biased state. If it does, your regulator is not regulating properly.

Jack E/NJ

[Ed Pitts]

Jack, you can use either method to excite the alternator; yours or mine, they both will work fine. Why have a light in the circuit when you can use the diode. If you don't have a light or diode in the ignition hook up, the engine would continue to run when you turn off the ignition switch. You can also hook the white wire to your stop light switch and you can push on the brake pedal to excite the alternator and then you don't need a light or diode. The big advantage of the three wire is if you have a problem, you can go to any Auto Zone or O'Rileys and pick up a rebuilt alternator to bolt on.
Ed

[mralternator]

This Problem can be solved in a few different ways, depending on the style of alternator used, There are now regulators that can be changed to turn on quicker, and also the most important factor is the air gap between the rotor and stator, too many times someone buys an alternator at a parts store and because of the manufacturing process they cut down the rotor and even sand down the stator because the application has an ignition on it, the air gap isn't a problem, I can assure you it isn't an expense fix either , contact me and I can provide you with more information if you like

[mralternator]

And Actually , after an alternator is turned on, It will charge until shutoff

[Bluebell]

...For the same reason, that you can't push start a battery ignition vehicle with a dead flat battery, that is fitted with an alternator, but you can when it has a generator.
The generator holds residual magnetism in the pole shoes (and is self excited) An alternator has to be fed to start. (it has to be excited... electrically speaking)

[mralternator]

An Alternator has to have battery voltage connected to it, and actually for Good cause, as NOONE , even the generator guys wants you to run there system on a dead battery or even a low battery for any period of time, YES the GENERATOR will Generate power , Hence the name with no power hooked to it, BUT this will most definitely over heat the generator as it is not designed to charge that high for along time period if at all really,
The Alternator will do a better job and quicker , BUT then again it will severely take away life from the unit. The Alternator has much more cooling design put into it as the Generator has NONE, It is ALWAYS recommended to charge the battery as much as possible to prolong the life of every charging device.
The self exciting comes from a few different areas, The rotor spinning creates AC, some tap off of this initial AC charge and use it to activate the regulator.

[Bluebell]

Mr Alternator, Don't take me wrong. I'm not knocking the alternator, just explaining that side of the differences. An alternator will deliver its rated output eg a 55 amp alternator can deliver 55 amps, continuously. The biggest demand being when the battery is at its lowest.
They also, by design have a much longer service life (potentially more reliable)

[mralternator]

No sir, no ill will intended , Just explained that yes you are correct , that a generator will charge with out any voltage attached to it, and just wanted to explain the hazard of running any system this way, and even with a low charged battery. I am hoping that everyone will understand this better and try to keep there battery charged to its fullest before operating any system, and a FYI as a Delco Remy Technical Representative, it is true that an alternator rating is not its true maximum output, example a 105 amp rated alternator will in fact produce 118 amps at a certain rpm