Brain fart regulator question Options

[mb911]

I’m going to post one more which is Spoke’s simplified schematic for an alternator and 3 pin regulator

I did a strike through on a line that has no bearing to your issue.

As previously noted the voltage on the field (DF) will vary based on battery state of charge and the electrical load the system is seeing. A higher voltage on DF indicates the system is “pushing” the alternator harder and trying to increase alternator output.



Note: color codes on this reflect the /4 914 regulator wiring. The other illustration is from a 911 factory manual and 911 wiring, thus the difference in color of wires.

Note 2: the voltage measurement of DF is referenced with the regulator plugged in and functioning by rapidly energizing and de-energizing the solenoid coil within the regulator.

Thanks that will help me track it down

[bkrantz]

Wait ... someone makes a brain fart regulator? (IMG:style_emoticons/default/blink.gif) I could use one of those at work! Where can I order one?

Yeah, that's what I was hoping to learn about. (IMG:style_emoticons/default/chair.gif)

[windforfun]

(IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif)

[Dave_Darling]

Where are you taking the voltage reading from? If it's the standard center console gauge, it's normal for it to read low. And change a lot depending on the electrical load on the system, particularly turn signals and such.

--DD

[rgalla9146]

Ben your VR and Alt are both SEV Marshal...so should be compatible.
You're in a certain era of 911 equipment ('74-'77 ?) so keep that in mind.
I feel for you... I recently did the whole job ....engine in the car only to discover a
loose wire on the back of the alternator. (IMG:style_emoticons/default/sad.gif) My own mistake from 2009

[ClayPerrine]

Ben,

I would suggest running a "full field test" on your alternator. Disconnect the regulator, and start the car. With a DVOM connected to the battery posts, apply positive voltage to the DF wire that attaches to the voltage regulator using a wire from it to the positive battery post. You should hear a whine as the alternator goes to maximum charge, and you should see 15 Volts or more on the DVOM.

If you don't, you have a bad alternator. If you do, it is a problem with the regulator.

[mb911]

Where are you taking the voltage reading from? If it's the standard center console gauge, it's normal for it to read low. And change a lot depending on the electrical load on the system, particularly turn signals and such.

--DD

Right at the battery

[technicalninja]

Ben,

I would suggest running a "full field test" on your alternator. Disconnect the regulator, and start the car. With a DVOM connected to the battery posts, apply positive voltage to the DF wire that attaches to the voltage regulator using a wire from it to the positive battery post. You should hear a whine as the alternator goes to maximum charge, and you should see 15 Volts or more on the DVOM.

If you don't, you have a bad alternator. If you do, it is a problem with the regulator.

(IMG:style_emoticons/default/agree.gif)

Bingo!
It's been a LONG time since I full fielded one.

Only way to go with an external regulator.

All alternators have a "thermal cut" in speed.

You need 1500-2000 rpm to properly load test an alternator/generator.

[mb911]

I want to quantify a few things. As rpm increases I do see charging just not what I would expect, alternator has a few thousand miles on it from @mepstein and his rebuild source, the charge voltage was spot on last fall when I put the car away for the winter, I just cleaned up wiring but did change out the voltmeter I had for an integrated unit from John bell, the battery is 10 years old just confirmed this morning, I am changing that out today, one thing I noticed a few weeks back as the battery tender was on the battery isolated from the car is that the tender was charging the battery for a day and getting hot. I assumed it was a bad tender and bought a new one. It’s the name brand battery tender so not sure what was going on. I will verify everything today maybe. It’s like Texas up here not sure how you guys work in that temp on the regular

[ClayPerrine]

It’s like Texas up here not sure how you guys work in that temp on the regular

Dude.. you get used to it. And we adopted the Mexican's siesta mentality. If we have to work outside, we get up early and work until noon, then sleep in the hot afternoon and go back to work in the evening when it cools down.

Me personally, I put AC in my garage. (IMG:style_emoticons/default/piratenanner.gif) (IMG:style_emoticons/default/piratenanner.gif)


I can't see how you can survive the winter cold up there. I am bundled up in a heavy coat when it gets below 40 degrees F. And I HATE snow! (IMG:style_emoticons/default/mad.gif)

[mb911]

It’s like Texas up here not sure how you guys work in that temp on the regular

Dude.. you get used to it. And we adopted the Mexican's siesta mentality. If we have to work outside, we get up early and work until noon, then sleep in the hot afternoon and go back to work in the evening when it cools down.

Me personally, I put AC in my garage. (IMG:style_emoticons/default/piratenanner.gif) (IMG:style_emoticons/default/piratenanner.gif)


I can't see how you can survive the winter cold up there. I am bundled up in a heavy coat when it gets below 40 degrees F. And I HATE snow! (IMG:style_emoticons/default/mad.gif)

That’s a good idea. Did a little bit this morning after the gym, then maybe a nap today then back at it. Gotta figure out autotune on megasquirt as well but tuning in this weather sucks

[Superhawk996]

Just know that if you full field it - you will get an uncontrolled voltage well over 14v.

If you have other electronics in the car that aren’t over voltage protected (not sure on MS specs) disconnect them before full fielding.

[mb911]

Just know that if you full field it - you will get an uncontrolled voltage well over 14v.

If you have other electronics in the car that aren’t over voltage protected (not sure on MS specs) disconnect them before full fielding.

Good point that would be bad

[mb911]

So verified some basic connections and ohms tested the wiring. The 12v wire all good. Ground good. dF is weird as I get different values depending on what 12 pin connection I check. I know that’s not a field test but now concerned I could blow something out with over voltage

[mb911]

Oh but the interesting thing is the battery light does go out when the car starts. Gonna verify tomorrow that it has the right bulb in it though

[Superhawk996]

dF is weird as I get different values depending on what 12 pin connection I check. I know that’s not a field test but now concerned I could blow something out with over voltage

The DF varying by where you test it may be a sign you’ve got some voltage drop going on. Either within the relay board multipin connector (pin 2) or within the board between pin 2 and DF. Might try a quick clean up of pin 2 and its female counterpart.

I wouldn’t worry about it going over voltage from varying DF due dirty connections. If anything voltage drop might be why you’re seeing only 13v instead of something more solid like 13.6 - 14 volts.

One other thing about DF is that it usually isn’t a rock solid stable voltage. It’s the nature of the beast (mechanical regulator) due to the regulator solenoid serving as a sort of very crude pulse width modulation of the field. Some fluctuation is normal as DF leads and lags the actual alternator output. Example if you measure pin 2 and then take a minute or two to remeasure over at 3 pin DF connection, the voltage may have already changed a volt or two.

The ultimate judge is what’s coming off D+ and B+ (alternator output to battery positive).

[emerygt350]

A hair off topic, and not to hijack, but why is the vdo volt meter so wonky? Mine is running right off the battery but it still isn't reliable (it just doesn't respond to the brake/turn signals anymore).

[Superhawk996]

A hair off topic, and not to hijack, but why is the vdo volt meter so wonky? Mine is running right off the battery but it still isn't reliable (it just doesn't respond to the brake/turn signals anymore).

I’m confused. So you want it bouncing around? (IMG:style_emoticons/default/confused24.gif)

If you are running it right off the battery it should be stable. The battery (in theory) is an infinite current source and its voltage should remain unaffected by minor loads like a turn signal bulb.

The OEM red / white wire that supplied the volt meter ran a convoluted route from battery to fuse 9, to the stop switch, and then to the volt meter and is subject to variance and voltage drops across lots of wire and the fuse. That red / white wire also went to a number of other locations that could load it down.

Easy enough to go back to original if you miss the variability dependent on load. (IMG:style_emoticons/default/shades.gif)

[mb911]

dF is weird as I get different values depending on what 12 pin connection I check. I know that’s not a field test but now concerned I could blow something out with over voltage

The DF varying by where you test it may be a sign you’ve got some voltage drop going on. Either within the relay board multipin connector (pin 2) or within the board between pin 2 and DF. Might try a quick clean up of pin 2 and its female counterpart.

I wouldn’t worry about it going over voltage from varying DF due dirty connections. If anything voltage drop might be why you’re seeing only 13v instead of something more solid like 13.6 - 14 volts.

One other thing about DF is that it usually isn’t a rock solid stable voltage. It’s the nature of the beast (mechanical regulator) due to the regulator solenoid serving as a sort of very crude pulse width modulation of the field. Some fluctuation is normal as DF leads and lags the actual alternator output. Example if you measure pin 2 and then take a minute or two to remeasure over at 3 pin DF connection, the voltage may have already changed a volt or two.

The ultimate judge is what’s coming off D+ and B+ (alternator output to battery positive).

Today I am digging into to gauges. That is the other area I messed with over the winter.

[mb911]

Ben,

I would suggest running a "full field test" on your alternator. Disconnect the regulator, and start the car. With a DVOM connected to the battery posts, apply positive voltage to the DF wire that attaches to the voltage regulator using a wire from it to the positive battery post. You should hear a whine as the alternator goes to maximum charge, and you should see 15 Volts or more on the DVOM.

If you don't, you have a bad alternator. If you do, it is a problem with the regulator.

@ClayPerrine thanks for this. Was super nervous about doing this but checked this morning and appear alternator is perfectly fine so need to get a regulator I guess. I did pop the cover off my regulator not sure what to check so may have to go digital but at least the engine doesn’t need to come out