6v Alternator

[DBSHELTON]

I converted a GM alternator to 6v positive ground with a kit. Installed it on my 29 Tudor. You have to rev the engine to excite it to charge. Is this common?

[Bill G]

That's the way mine works.

[alexiskai]

Mine too, that's normal. You can rev it when you start up, or you can just let the car run off battery for the first few minutes until it kicks in on its own.

[Mike Peters]

ditto.

[McMimmcs]

I think that Is the way they have to be excited to start, Certainly no big deal once you realize what you have to do. It becomes instinct! .

[DBSHELTON]

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Thanks, I figured that was the case, just wanted other opinions. The alternator in my other Model A seems to have a lower cut-in point but that may be due to the little-bit smaller pulley.

[MrBruce]

You can buy the smaller pulley from most Model A vendors and it will kick in quicker.

[DBSHELTON]

I have the one available at the Model A parts dealers, but the one on my other alternator is even smaller.

[Jim/GA]

When you use the small diameter pulleys on an alternator, you will get better belt grip on the pulley, without a lot of belt tension, if you use a fan belt with the little V-notches in it on the inside surface.

Example:



The exact belt you get will depend on the circumference you need for your engine setup. I don't want to quote a belt number and have it be wrong for your car. Work with your parts supplier.

.

[Bob Bidonde]

The alternator needs a small current flow through its field windings to start. The starting current in a modern car occurs when the charging light goes on as the car is started. I have an alternator in my Coupe that does not self start and requires revving the engine. To the contrary, I have a Nu Rex alternator in my Victoria that self starts. So there is a way of making your alternator self start, but I am not sure to do this.

[DBSHELTON]

I know you can ground the #1 terminal on it momentarily and it will start charging.

[VinceBlack]

You can add an exciter wire to the 2wire plug-in, no.1 is excite term no.2 is voltage sense. Add a wire to no. 1 run into cab, by momentarily ground wire alt will start charging. Or you can add a resistor inside of alt to help turn on faster. There are several ways that will help.

[Y-Blockhead]

Best I have found is to not worry about it. I just drive slowly up the street and by the time evrything is starting to warm up it is showing a charge.

I now have a PowerGen and it does not have that non-issue. It charges right from the get-go.

[rfitzpatrick]

And I thought it was notched for cooling !!
You ever consider writing a book -- for those's of less common sence, such as myself?


Example:



The exact belt you get will depend on the circumference you need for your engine setup. I don't want to quote a belt number and have it be wrong for your car. Work with your parts supplier.

.[/QUOTE]

[Jim/GA]

Originally Posted by rfitzpatrick

And I thought it was notched for cooling !!
You ever consider writing a book -- for those of less common sense, such as myself?

I'm glad you find my little tips helpful.

I do not plan to write a book. I have been writing "Jim's Tech Tips" monthly for MAFCA for a couple of years now. They include it in a monthly email blast that they send to Members, and in another monthly blast to all of the Chapter newsletter editors, for clubs to put in their newsletters.

If you want to get the email blast each month, send your email address to modelagarth (at) yahoo (dot) com

.

[DBSHELTON]

I went ahead and installed a momentary switch to ground on the #1 terminal. Now one touch and it is charging. Makes me feel better anyway.

[BRENT in 10-uh-C]

Originally Posted by DBSHELTON

I went ahead and installed a momentary switch to ground on the #1 terminal. Now one touch and it is charging. Makes me feel better anyway.

So on a similar note, what do you do about the self-exciting regulator that constantly has a parasitic draw on the battery?

[Mulletwagon]

Originally Posted by Jim/GA

When you use the small diameter pulleys on an alternator, you will get better belt grip on the pulley, without a lot of belt tension, if you use a fan belt with the little V-notches in it on the inside surface.

Example:



The exact belt you get will depend on the circumference you need for your engine setup. I don't want to quote a belt number and have it be wrong for your car. Work with your parts supplier.

.

Yep, that would be your BX40 or slightly larger BX41. This is known as a cogged belt.

[DBSHELTON]

Originally Posted by BRENT in 10-uh-C

So on a similar note, what do you do about the self-exciting regulator that constantly has a parasitic draw on the battery?

Beats me!

[Synchro909]

Originally Posted by BRENT in 10-uh-C

So on a similar note, what do you do about the self-exciting regulator that constantly has a parasitic draw on the battery?

I use an isolating switch on the earth side of the battery. There can be no parasitic draw if the battery is not connected.

[loowiloowi]

I thought that all driver Model A's had a battery disconnect on the ground side....

[DBSHELTON]

Originally Posted by loowiloowi

I thought that all driver Model A's had a battery disconnect on the ground side....

Does that really matter? Mine are on the Minus side.

[BRENT in 10-uh-C]

Originally Posted by DBSHELTON

Does that really matter? Mine are on the Minus side.

Ground side and Minus side can be two totally different items.

In a nutshell, interrupting the ground circuit to the battery does nothing if the circuit is re-connected by a battery that rubs against a grounded object, -or has a brake rod/etc. become the new ground. On the other hand, when the power source is disrupted through a switch, it does not matter if something shorts out the ground circuit.

[DBSHELTON]

Originally Posted by BRENT in 10-uh-C

Ground side and Minus side can be two totally different items.

In a nutshell, interrupting the ground circuit to the battery does nothing if the circuit is re-connected by a battery that rubs against a grounded object, -or has a brake rod/etc. become the new ground. On the other hand, when the power source is disrupted through a switch, it does not matter if something shorts out the ground circuit.

I am now confused. So, on a positive ground system, would you install the disconnect switch on the + battery terminal cable or the - battery terminal cable.

[Badpuppy]

Install the switch between the frame and whichever battery post should be grounded.

[BRENT in 10-uh-C]

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Originally Posted by Badpuppy

Install the switch between the frame and whichever battery post should be grounded.

Ummmm, ...that really is not the way it is supposed to be done. The interruption needs to be between the battery and the main power line feeding all of the circuits power. In the case of the Model-A, this is the wire feeding the starter switch which has the chassis wiring harness attached.

Whether the Model-A is wired positive or negative ground in this instance is moot.

[BRENT in 10-uh-C]

Originally Posted by DBSHELTON

I am now confused. So, on a positive ground system, would you install the disconnect switch on the + battery terminal cable or the - battery terminal cable.

Lets break this down further. Pretend you remove the "+" and the "-" labels from the battery. At this point, it really does not matter whether it is considered a + ground or - ground when you connect the battery cables, -especially if the battery's current has been drained.

So if the disconnect switch is placed in the cable between the battery post and the chassis ground, even with the switch turned off, I can potentially lay a screwdriver (-or any piece of metal) on top of the battery and over to any component (frame, transmission, brake rod, etc.) and re-connect the ground to the system. Therefore having the disconnect in the ground cable is useless. Now if the disconnect switch is placed in the battery cable connecting the starter switch to the battery post, any short that happens on the opposite side of the switch (opposite side of battery post) can have the power disrupted and stop any short from creating a fire.

Does this help you understand??

[Badpuppy]

Either way interrupts the current path. With the switch open, the only way you get a short is directly across the battery posts. Placed on the hot side the switch exposes more bare metal to the post area. On ground side no worries using a metal tool or extension to operate it.