generator light

[Member 10617]

KVH,

Seems to me it should be entirely off when you are running.

 

[Member 10617]

Let me ask once more. When hooking up the voltmeter to the control box, how is this done? What is the setup for the wire connections and what is the process? Also, in connecting the terminals, is there a specific gauge of wire you need to use? I'm speaking of the test that you need to make when you want to adjust the screw in the back of the control box. (A photo would be great help...)

 

[ArcticOne]

Ed

I have 10 PDF's dealing with the Lucas Dynamo and Control Box. They cover some of the questions that you ask.

PM me your email address and I can send them to you. Absolutely FREE, no charge, no shipping fees, no handling fees. When was the last time you heard that in mid December???



By the way - did anybody else notice that you can break the Christmas lights at the top of the page?? Move your cursor over the light and watch them explode - if you have your speakers turned on they even make a noise. WEEEEEE, great fun.

jb

 

[Member 10617]

Hi, JB,

Many thanks. I already have the PDFs of the Lucas Dynamo and Control Box instructions, but even with them I'm not altogether clear on how to set up the wiring to check the box: exactly where to attach the wires, what gauge wire to use, how to hook up the voltmeter -- pretty basic stuff not covered in the Lucas instructions.

 

[sp53]

Yeh I need to switch to decaf plus I was in high school in the late sixties. Anyways, I did it again,I hooked the meter up wrong and measure across A1+A to D and did not hook up to ground. Moreover, thanks for hanging in there with me Randall, I appreciate it. When I did set the meter up correct, I got 15.5 volts so good. I looked things over for Bad connections and did clean up a couple. The ignition is newer, and I could not feel any warm wires. One thing I did notice was that if I turn everything on including the parking lights, but leave off the head lights, the gen light does not have that very slight dim glow. Perhaps the head light switch has some resistance. I do not like how they have 2 large wires going to one pole (blue and brown) and the switch is original.

 

[TR3driver]

Let me ask once more. When hooking up the voltmeter to the control box, how is this done? What is the setup for the wire connections and what is the process?

There are different connections required for different tests. For checking the regulated voltage, the voltmeter needs to be connected from the D terminal to ground (which can be either the E terminal or any good solid ground point).

Mechanically, it's best to have leads that end in alligator clips. Some meters will come with clips already, so just use them.
https://www.sears.com/shc/s/p_10153_12605_00920925000P?sid=IDx01192011x000001

With most meters, you'll need some way to adapt the meter probes. I generally use what I've always called "clip leads", but Radio Shack calls them "Test Jumpers"
https://www.radioshack.com/product/index.jsp?productId=2062660

Also, in connecting the terminals, is there a specific gauge of wire you need to use?

No. The voltmeter draws essentially no current and so using even very small wire will not affect the reading. It's best not to go too small though, just because the wires become mechanically fragile. Bigger wires are stiffer though, which becomes a hassle if you go too big. So I'd say anything from, oh, 24 AWG up to maybe 16 AWG will work fine.

 

[Member 10617]

Randall,

Many thanks. That gets me part of the way there. But here, in more detail, is my question:

The Lucas instructions read as follows: "Disconnect A and A1 leads, this will disconnect the battery from the generator and take the series windings out of circuit. Connect a voltmeter between the regular frame or "D" terminal, and earth. Join the A and A1 leads to provide an ignition feed." -- This is the connection that I'm not sure about. Use a wire and two alligater clips? But what gauge wire joined by the clips?

The instructions continue: "Start the engine and run up to charging speed; the voltage reading will increase until the setting point of the regulator is reached and there should then be no further increase. If the voltage does not conform to specification for the particular model, turn screw (Fig. 7-1) inwards to increase the voltage, or outwards to lower it, then re-check reading."

And, to further complicate matters, the setting given by Lucas is not the same as the setting given by Moss. The explanation from Moss is that times have changed....

According to an article by Moss (Oct. 2010) "The point at which the contacts open (around 8.5 to 11 volts) is known as the drop-off point.... The point when the contacts close is usually adjusted so that the internal voltage of the regulator is about 12.7 to 13 volts."

But the latest instructions from Moss indicate that "The cut-out relay should be adjusted so that the points open at 10 to 12 volts." And ... "The regulator relay should be adjusted so that the points open at 13 to 14 volts."

According to Haynes, the cut-in voltage is 12.7 to 13.3 v. And the drop-off voltage is 8.5 to 10.0 v. (Same as the Service Manual).

See my problem?

 

[KVH]

I'd like to know more here, and I say that realizing that if I dug through the archives long enough I'd find the answers, but here are my questions:

a) what are the two cut-outs in the Voltage Regulator, and what function is each performing?

b) how is it that bringing voltage to one side of the ignition light from the Voltage Regulator and to the other side from the Battery, via the solenoid and ignition switch, somehow turns the light off? I'm imagining some balancing of power from two opposite sides, like a reverse tug of war, but what happened to the positive and negative that turned the light on in the first place?

I've never understood auto electrics!

 

[TR3driver]

a) what are the two cut-outs in the Voltage Regulator, and what function is each performing?

There are two relays in the control box. One of them (the one with the screw on the upper contact) regulates voltage and current, by virtue of having two windings on it. It has "normally closed" contacts, so when the relay is not energized, the contacts bypass the resistor in the field circuit and apply full generator output voltage to the field coils inside the generator. When either voltage or current rises high enough to move the armature, the contacts open and the resistor limits the current through the field coils to a small value.

The other relay, commonly known as the cut-out relay, is what connects the generator output to the battery. It is necessary to prevent (or at least limit) reverse current flow through the generator, as otherwise it will drain the battery when the engine is not running (and potentially overheat the generator as well). The generator will actually double as an electric motor and try to turn the engine. It can't, of course, but it will try. The cutout relay also has two windings, one of which senses generator output voltage and the other generator output current. The voltage winding is what closes the relay initially, but then when current starts to flow backwards into the generator, the current winding fights the voltage winding and the relay is released. When it opens, it interrupts the current, and then stays open until the voltage comes back high enough to close it again.

b) how is it that bringing voltage to one side of the ignition light from the Voltage Regulator and to the other side from the Battery, via the solenoid and ignition switch, somehow turns the light off? I'm imagining some balancing of power from two opposite sides, like a reverse tug of war,

Yeah, I guess you could look at it that way.

but what happened to the positive and negative that turned the light on in the first place?

Normally, the light comes on when you turn the key on, because the ignition is supplying 12v to one side of the lamp, and the other side is grounded through the generator armature. When the engine starts, the generator starts producing voltage and the voltage on the 'D' terminal (which is connected to the armature through the brushes) comes up. When it gets close to 12v, the light goes out because it now has 12v on both sides.

Does that help?

 

[Member 10617]

So.... given the 2 Moss, Haynes, and Shop Manual specifications, which is "correct"?


Sure would help if someone could provide a photo of the connectons in place and voltmeter hooked up to test volts. And, does this hook-up give you both the cut-in and cut-out volt readings?

 

[KVH]

Yes, very much. Thanks. A follow up:

. . . . so when the relay is not energized, the contacts bypass the resistor in the field circuit and apply full generator output voltage to the field coils inside the generator. When either voltage or current rises high enough to move the armature, the contacts open and the resistor limits the current through the field coils to a small value.

The generator applies its own output voltage to the field coils in the generator itself? And when you say the output will rise high enough to move the armature, that confuses me. I thought only the fan belt moves the generator's armature. I'm embarrassing myself, but I'm used to it. Trust me.

. . . The generator will actually double as an electric motor and try to turn the engine. . . .but then when current starts to flow backwards into the generator, the current winding fights the voltage winding and the relay is released. When it opens, it interrupts the current, and then stays open until the voltage comes back high enough to close it again. . . .

So it's analogous to a back flow valve or anti-siphon valve? Charge can't go back to the generator?

Thanks!

 

[TR3driver]

The generator applies its own output voltage to the field coils in the generator itself?

Yes, through the voltage regulator contacts in the control box. It seems like an odd way to do it, but there is actually a method to the madness. By making the generator self-exciting (rather than drawing power from the battery), it won't draw from the battery when the engine isn't running, which might overheat the coils (and run the battery down).

And when you say the output will rise high enough to move the armature, that confuses me. I thought only the fan belt moves the generator's armature.

Sorry, that was my bad. The part of the relay that moves is also known as an armature, but it was a poor choice of words. My point was that when either voltage or current rises too high, the regulator relay contacts open and reduce the generator field current, which reduces the output of the generator. Normally, this open-close-open cycle happens too fast to see, but under some circumstances it can be slow enough to make the ammeter jump around.

So it's analogous to a back flow valve or anti-siphon valve? Charge can't go back to the generator?

Yes, exactly. A big diode would do the same thing (more or less), but solid state diodes hadn't been invented yet when this circuit was designed. Alternators have diodes, so they don't need a cutout relay.

 

[TR3driver]

Join the A and A1 leads to provide an ignition feed." -- This is the connection that I'm not sure about. Use a wire and two alligater clips? But what gauge wire joined by the clips?

Sorry, Ed, I forgot that part since I don't do it that way. The temporary connection only needs to carry a few amps (just to run the ignition coil) and some voltage drop here won't affect what you are measuring. So the wire gauge is not critical and one of those Radio Shack "Test Jumpers" would do fine. Or if you have a somewhat larger alligator clip, you can just stuff both wires into the same clip and not worry about the wire at all (except to be sure it can't short to anything).

The instructions continue: "Start the engine and run up to charging speed; the voltage reading will increase until the setting point of the regulator is reached and there should then be no further increase. If the voltage does not conform to specification for the particular model, turn screw (Fig. 7-1) inwards to increase the voltage, or outwards to lower it, then re-check reading."

Any questions about that part? BTW, the screw setting is very sensitive to tiny changes. Move it only a tiny fraction of a turn before rechecking the voltage. If you have the earlier style box where there is a lock nut on the adjusting screw, I recommend also tightening the lock nut before making the check, as tightening it will make some small difference.

And, to further complicate matters, the setting given by Lucas is not the same as the setting given by Moss. The explanation from Moss is that times have changed....

According to an article by Moss (Oct. 2010) "The point at which the contacts open (around 8.5 to 11 volts) is known as the drop-off point.... The point when the contacts close is usually adjusted so that the internal voltage of the regulator is about 12.7 to 13 volts."

But the latest instructions from Moss indicate that "The cut-out relay should be adjusted so that the points open at 10 to 12 volts." And ... "The regulator relay should be adjusted so that the points open at 13 to 14 volts."

According to Haynes, the cut-in voltage is 12.7 to 13.3 v. And the drop-off voltage is 8.5 to 10.0 v. (Same as the Service Manual).

See my problem?

Sorry, I guess I don't, really. I've mentioned before that I do not agree with Moss on these points, so I'm not interested in trying to explain their point of view. 12.7 is simply not enough to fully charge the battery, IMO. You'd have to ask them why they would recommend such a thing. Unless you are using an Optima battery, the battery chemistry (and hence voltages) are just the same as they were in 1950.

And 12.7 isn't enough to charge an Optima, either. (Optima recommends 13.65 to 15.0)

In the RB106 regulator used on TR2-4A (both -1 and -2 varieties), the regulator relay responds to both current and voltage, meaning it actually reacts to the sum of them. Hence the regulated voltage will be affected by the current that is flowing at the same time. The battery also has a current/voltage relationship, which changes depending on how well charged the battery is. So it is difficult, if not impossible, to get a reliable adjustment with the battery in-circuit. That is why the book procedure calls for isolating the generator and regulator from the battery (by either disconnecting the wires on A & A1; or by inserting a piece of paper into the cutout contacts); and then using an unusually high set point for the voltage adjustment. The actual regulated voltage once the battery is reconnected will always be lower, because of the current drawn by both the battery and the ignition system.

The other thing to watch out for is that the "cut-in" and "drop-off" voltages are for the cutout relay, not the regulator relay. Only the "cut-in" voltage gets adjusted, the "drop-off" voltage is just a specification that, hopefully, results from the relay being adjusted as given in the procedure.

Personally, I use the numbers given in the TR2/3 workshop manual. They were revised slightly upwards later on (the numbers in the Haynes are the same as the TR4 workshop manual, I believe), but I feel the higher numbers produce a bit too much overcharging while running with just the ignition. There is definitely a compromise to be made; the lower setting will allow the battery to become slightly discharged when running with the headlights on, but also reduce the amount of acid vapor blown around with the headlights off (and possibly increase the life of the battery).

 

[Member 10617]

Randall,

I must be missing something. You write that you don't agree with Moss and say that 12.7 is simply not enough to fully charge the battery. But Haynes and the workshop (Service manual) call for the same voltage..?

To get things clear in my mind, in your opinion:
What is the ideal cut-off voltage?
What is the ideal cut-in voltage?

Here, again, is what Moss says: "We realize that these are not the specifications in the workshop manuals for cars equipped with these regulators. They are more conservative, and perfectly functional. Using these settings will minimize the chance of a problem with your new regulator and extend the life of your battery. The procedure for adjusting the two relays in the voltage regulator are covered in the workshop manual for your car. The procedure is somewhat complicated, and it takes some specialized equipment. Note that the settings for the relays in the workshop manual SHOULD NOT BE USED. Refer to linse 101 and 102 above. Because new tools are available, the instructions are a little dated. Most voltmeters today are digital, not analog. If you are not familiar with the procedure, and are not comfortable doing this yourself, there are a couple of options.... Having it done by a professional, or buying a pre-tested & adjusted regulator."

Everything else you write is clear and explains much of what has been a mystery to me. Many, many thanks.