Voltage Regulator (ext.) / How it works (7 Viewers)

bj40green

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A lot of you don't like electric stuff and especially not complicated things like an external Voltage Regulator. So maybe it's time to explain how this black box with 3 or 6 wires works. It's really pretty simple.

A VR (Voltage Regulator) regulates the charging process of the alternator. Our mechanical VR's have only 3 positions.

Position 1. Full charge
The battery voltage is less than 13.6V.

Position 2. Trickle (or Half) charge.
The Voltage is 13.6V. The battery is now fully charged and needs only to be topped off.

Position 3. No Charge / the battery is full and more charging will damage (cook) the battery.
The Voltage is 14.4V (or between 14.4 and 14.8 depends on the factory setting aka "set point")

Here is the Toyota explanation from the FSM (Factory Service Manual)


I've "translated" the FSM diagram in this one which is easier to read and understand.
The left part of this diagram is the alternator, the right part shows the Voltage Regulator.
No matter if the VR has 3 or 6 wires, there is always a E, IGN and F wire/terminal.
The other 3 are N, L and B in case of a 6 wire VR. More about this later.
E = Earth / Ground
IGN = Voltage from the Ignition key (= battery voltage) aka "Sense".
This voltage is used to detect how high the battery voltage is.
F = Field. This voltage activates the alternator and controls the output voltage of the alternator.

Look at the VR part of the diagram. The heart of the Regulator is a 3 way switch that is activated by magnetism. Most people call this a relay which is in a way correct.

The switch is pulled closed in the top (1st) position by a spring.
The Voltage from the battery (passing the ignition key) goes directly to the F terminal. Therefore the alternator is activated to charge with full power. Note: The resistor is bypassed / overruled / shortened out.

When the voltage goes up, the coil of the switch is energized and builds up a magnetism that starts pulling the switch to the 2nd position.
When the battery voltage reaches 13.6V the coil is enough energized to actually pull the switch to the 2nd (open) position.
At this point the switch is open and the 10 Ω (ohm) resistor is now in series with the F terminal. The voltage to the F terminal and thus the alternator, is reduced to approx. 6 to 7V.
The output of the alternator is now decreased and the battery will be Trickled charged.

The battery voltage will continue climbing until the Voltage is 14.4V. At this point the coil is so much energized that it pulls the switch in the 3rd position.
When the switch is in the 3rd position the F terminal is grounded so the charging process is stopped.
Unfortunately (or on purpose by design, I haven't figured that one out yet) now the V ignition is also grounded via the resistor and this creates a lot of warmth and makes the VR feel pretty hot.

Here is the same story but now in a graphic.


Here are 3 pics with the different positions.

Full charge


Trickle or Half charge


No charge / Battery is Full


I also made little movie so you can see it live!



Rudi
 
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bj40green

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Thanks for the write up!

FYI images show an error when clicking on them.

I checked on both my computers with Explorer, Firefox and Chrome and have no problems with the pictures when clicking on them.
What error message do you get?
Are U using a PC or some handheld iPhone/tablet thingy?

Rudi
 
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I checked on both my computers with Explorer, Firefox and Chrome and have no problems with the pictures when clicking on them.
What error message do you get?
Are U using a PC or some handheld iPhone/tablet thingy?

Rudi

Works for me way over here in tiny little New Zealand Rudi :)

thanks...
 

Vae Victus

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Using the app on iPad. Shows connection error, but clicking the arrow for the next picture brings it up. Then clicking the previous button brings up the first pic. FYI.
 

Coolerman

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Awesome write up Rudi! :clap:
Your video shows exactly how the three stages work. Did you use a variable power supply to trigger it? That's how I test and adjust my regulators.
 

bj40green

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Thanks guys.

@Coolerman: Yes I use this power supply
DSC00823.JPG

Rudi
DSC00823.JPG
 
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Thanks, Rudi! How would I be able to adjust the voltage level down a bit? By bending the P1 bar outward a little?
 

SouthBostonFJ40

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Rudi,
Thanks! If you could do a write up on switching to an internally regulated alternator and getting rid of the VR all together, that would be great.
 
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Thanks for the write up! So if your VR died in the middle of nowhere could you wire the F terminal on your alternator to battery voltage to make it home? Would you have to cycle the connection on and off to prevent over charging?
 

bj40green

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Thanks, Rudi! How would I be able to adjust the voltage level down a bit? By bending the P1 bar outward a little?

Here are some pics from the FSM how to do the adjustment
adjusting voltage regulator.JPG

VR adjustment 1.JPG

And one from myself to show what to touch and what not.
DSC06151_adjustment.JPG
NOTE: I wrote Do NOT bend/touch this spring which means don't try to make the adjustment bending this spring. This spring is the counter force for the coil.

You can do this with a running engine at 2000 rpm, a volt meter, a steady hand and the headlights on.

Wiggle the upper part of your pliers between the spring and the plate.


That plate is a tough cookie. It needs a lot of force to bend even a little. On the other hand it needs only a fraction to make a slight adjustment. So bend a little bit take away your pliers so that the force of the spring is not altered. Read your Voltmeter, and so on.

Good luck,

Rudi
adjusting voltage regulator.JPG
VR adjustment 1.JPG
DSC06151_adjustment.JPG
 
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bj40green

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Thanks for the write up! So if your VR died in the middle of nowhere could you wire the F terminal on your alternator to battery voltage to make it home? Would you have to cycle the connection on and off to prevent over charging?

Smart thinking Oregon! In theory you're right but............. there's always a but. If you connect F to the battery, the alternator keeps charging and charging 15V....16V.....17V.....18V..... do I need to go on?
If the VR dies, most of the time you can make it home on the battery. If the battery is in good shape you can drive a few hours before the ignition dies by starvation of voltage.
For DIESELS: Up to DEC '78 diesels can run with no battery at all.
From Jan. '79 the diesels are equipped with an EDIC system which needs power same as the ignition system for gassers.

If the battery is not in a good shape you can try this;
Connect F to +Batt and drive with low RPM's (around 1000 - 1200) and your headlights on. This way you keep the Voltage a bit under control. The alternator starts charging above 800 RPM.
NOTE: I don't recommend this method, but if you're in the middle of nowhere....

EDIT: keep a spare in your toolbox, better.... mount the spare on the inside fender.
DSC02072_text.JPG

Rudi
DSC02072_text.JPG
 
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bj40green

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Thank you so much, Rudi! Also, is it normal to see the VR getting hot, even to the point of light smoke venting out from the bottom of it?

YES and NO. When the VR is in the 2nd or 3rd position the resistor is in series with the F terminal. In the 2nd position (trickle or half charge) the resistor is getting pretty warm. When the VR is in the 3rd position (Battery is full / No charge) the resistor is grounded. A little calculations shows;
V = 14.4 Volt, R = 10 ohm, so the current = 1.4Amp
Voltage x Amps = Watts, so 14,4 x 1,4 = 20.16Watts.
That's pretty hot. The resistor is big enough to handle this but eventually the whole VR is getting pretty hot.
Did you touch the resistor? Maybe you left some grease or so on the surface which is now burning off.

Rudi
 
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Rudi,
Thanks! If you could do a write up on switching to an internally regulated alternator and getting rid of the VR all together, that would be great.

Easy done, I installed an internally regulated alternator intended for a 3F onto my 2F in an '81 FJ 45. Here's how:

The 3F alternator has a 3 pin plug, one pin is voltage sense, another is ignition, the 3rd is for the charge light. The ignition switched power and 12 volts from the battery for the sense wire are accessible from the 6 pin plug that used to be connected to that external regulator you've just tossed over the shoulder.:p

As for the charge light, the charge light pin hooks up to one side of either a dash light or resistor, the other side of the charge light hooks up to 12 volts switched from the ignition.

The charge light works this way: when the key is on but the engine isn't running, the 12 volt supply from the ignition turns on the charge light, once you start the motor, the alternator starts to produce power and now the L terminal of the alternator is at 12 volts, this means that both sides of the charge light are at the same potential and the light will go out. The alternator needs a charge light/resistor to work, no charge light = a non charging alternator. Of course, check the pinouts of your alternator.

HTH.:cheers:
 
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Also, for the diesels, the motor will still run with no battery, just that the edic system won't work, to start, tow it or roll down a hill. To stop the engine, stall it in gear or disconnect the edic arm off the governor and push the governor arm to the stop position.;)
 
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SouthBostonFJ40

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Easy done, I installed an internally regulated alternator intended for a 3F onto my 2F in an '81 FJ 45. Here's how:

The 3F alternator has a 3 pin plug, one pin is voltage sense, another is ignition, the 3rd is for the charge light. The ignition switched power and 12 volts from the battery for the sense wire are accessible from the 6 pin plug that used to be connected to that external regulator you've just tossed over the shoulder.:p

As for the charge light, the charge light pin hooks up to one side of either a dash light or resistor, the other side of the charge light hooks up to 12 volts switched from the ignition.

The charge light works this way: when the key is on but the engine isn't running, the 12 volt supply from the ignition turns on the charge light, once you start the motor, the alternator starts to produce power and now the L terminal of the alternator is at 12 volts, this means that both sides of the charge light are at the same potential and the light will go out. The alternator needs a charge light/resistor to work, no charge light = a non charging alternator. Of course, check the pinouts of your alternator.

HTH.:cheers:

Does this apply to an FJ60 alternator?
 

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