Adjustable voltage regulator...how to adjust?

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Johnny Mac

Johnny Mac

www.blueprintengines.com
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Here's a new one to me. Anyone know how to adjust one of these? Ever even seen one?

I assume this is in some sort of factory default position as it sits...but which way is more or less...I can't decipher.

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15596097251051639086697355890996.jpg
 
Typically the white dot in the center has a notch for a small screw driver. Turn and the voltage goes up or down dependent on direction. Looks like the person who built that one installed backwards.
 
Syleng1 said:
Typically the white dot in the center has a notch for a small screw driver. Turn and the voltage goes up or down dependent on direction. Looks like the person who built that one installed backwards.
Click to expand...
It's a bad picture. It does in fact have a slot where you can spin it...I guess my confusion is the fact that there are no discernable markings that mean anything I recognize...
 
Right increase, left decrease? Guess I will try it with a voltmeter.
 
The white dot is a "potentiometer" or sometimes called a "pot." Turning the pot adjuster to the right (clockwise) "should" increase resistance, thus dropping current flow. Counter clockwise should decrease the resistance and increase current flow. If wrong...I'll stand corrected.
 
circlepilot said:
The white dot is a "potentiometer" or sometimes called a "pot." Turning the pot adjuster to the right (clockwise) "should" increase resistance, thus dropping current flow. Counter clockwise should decrease the resistance and increase current flow. If wrong...I'll stand corrected.
Click to expand...
Thanks. Will give it a whirl. Trying to combat low voltage during idle as a result of a small diameter crank pulley. (Couldn't keep belts on at 7800)
 
Johnny Mac said:
Thanks. Will give it a whirl. Trying to combat low voltage during idle as a result of a small diameter crank pulley. (Couldn't keep belts on at 7800)
Click to expand...
Don't turn it in either direction too far, you can damage the pot and make any adjustments with the "power off."
 
circlepilot said:
Don't turn it in either direction too far, you can damage the pot and make any adjustments with the "power off."
Click to expand...
So make minor adjustments only, with the power to the vehicle off. Got it. Thank you
 
Transpo/ Wai Wei sells adjustable VRs and VR guts but never noticed any instructions in the catalogs. (A websearch for Transpo alternator parts should turn up a catalog)

Be interesting to see the results of your experiment.
It won't be surprising if a higher voltage setting has little to no effect at idle.
If the voltage is low at just at idle, the regulator is probably already maxing out the field current supply. The alternator is just turning too slow and the magnetic field is already fully saturated.

My understanding is maximum power output at a given rpm is fixed.
Power = Current x Voltage
We see this effect in reverse on older stock setups at idle. The alternator attempts to provide the current demanded with accessories on and the voltage drops a little.
So increasing the output voltage will cause the maximum current to go down.
Here's a representation of how increasing or decreasing the test voltage would change the maximum current an alternator can provide.
upload_2019-6-4_8-57-21.png


The Chrysler shop manual tests are done at 15 Volts, so they are conservative.
If a company wants to make their alternator output look better, they use lower voltage like 12.
 
small update. No difference with dial turn, so this one is either defective, or the "adjustment" is peak only, or is so small that its only .1 volts at idle. no difference vs my OEM napa replacement either (probably 10 years old). same idle volts, and appeared to be the same peak with a touch on the throttle. O well, live and learn.
 
Mattax said:
Transpo/ Wai Wei sells adjustable VRs and VR guts but never noticed any instructions in the catalogs. (A websearch for Transpo alternator parts should turn up a catalog)

Be interesting to see the results of your experiment.
It won't be surprising if a higher voltage setting has little to no effect at idle.
If the voltage is low at just at idle, the regulator is probably already maxing out the field current supply. The alternator is just turning too slow and the magnetic field is already fully saturated.

My understanding is maximum power output at a given rpm is fixed.
Power = Current x Voltage
We see this effect in reverse on older stock setups at idle. The alternator attempts to provide the current demanded with accessories on and the voltage drops a little.
So increasing the output voltage will cause the maximum current to go down.
Here's a representation of how increasing or decreasing the test voltage would change the maximum current an alternator can provide.
View attachment 1715344665

The Chrysler shop manual tests are done at 15 Volts, so they are conservative.
If a company wants to make their alternator output look better, they use lower voltage like 12.
Click to expand...
Thats good info there! so what i would call negligible output change probably "squeezed" my overall range with a tiny bump at idle, and less peak. I haven't measured it going down the track or anything, just some throttle whacks, and at idle. Wish i would have talked to you first! lol
 
Make sure you ground the regulator (I used a jumper cable). I adjusted mine for a max reading at speed of 14.5 volts.
 
superchargeddrt said:
Make sure you ground the regulator (I used a jumper cable). I adjusted mine for a max reading at speed of 14.5 volts.
Click to expand...
Yeah i bolted it back to the inner fender after adjusting it. did you spin yours Left or right to increase? i truthfully saw no difference with either max setting, other than perhaps .1 or .2 at idle on the voltmeter.

I put a voltmeter on the charging post, and the alternator is only putting out 12V at idle with NO accessories, and it'll only go to 14 when revved. Alternator drops clear to 10.8 when fan, fuel,water, are on. they think its more a factor of the alternator needing repaired, so may be more the ALT being unable to keep up with the load, opposed to the REG. since the reg can only put out what it gets from the ALT.
 
You may be right about needing s new alternator Mine runs 12.8 at idle with lights on, electric fans, Mallory 6AL and Fitech fuel injection. I am however running a chrome Powermaster 90 amp alternator. I have to turn my adjustment clockwise to increase the voltage
 
superchargeddrt said:
You may be right about needing s new alternator Mine runs 12.8 at idle with lights on, electric fans, Mallory 6AL and Fitech fuel injection. I am however running a chrome Powermaster 90 amp alternator. I have to turn my adjustment clockwise to increase the voltage
Click to expand...
Yeah, its a Tuff stuff 140 amp, so i think i've just worn it out over the 10+ years of ownership. I'm sending it up to them in cleveland and they're going to go through it. Good company, quick turn around. Then maybe my adjustable regulator will function, or maybe it won't even be needed. I know my small crank pulley probably slows down the charging, but the car labors with 40 degrees of locked timing to start (after a day or racing and idling through the pits) , even with not hitting the ignition until its fully cranking.
 
See if you can get them to give you a full test report which would include a max current vs. rpm test like above.
That test report came with a Chrysler revised squareback rebuilt in 2009.

Yes its possible that an alternator will work but with lower output. One bad diode, or like I found recently, the connection for one of the three stator windings was broken. So that alternator was roughly limited to 2/3 of its potential and the output wasn't as smooth.

My understanding is not all strategies to create higher output are helpful at increasing low rpm output.
Here's an example from the 2008 Delco Remy selection guide. (GM 10 SI alternators).
upload_2019-6-4_17-29-21.png

Depending on the pulley ratios and the loads at idle, the alternator rated "63 amps" could be a better choice than the "72 amp" version.

Some claim that an advantage of some of the newer alternator models is that the tolerances allow the rotor to run closer to the stator. This means the same magnetic field can induce more current out. Another advantage at low rpm may be wider windings.
I mention this because with what you're doing (EFI etc) I assume you're pretty open to fitting in a different type of alt if needed.
 
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