Charging Issue, Sporadic charging voltage Options

[slapshot]

I've been unable to figure out why my charging voltage is so sporadic. Charging voltage ranges from 12.35 volts to 16+ volts. I first noticed this 2 months ago but it could have been going on since I got the car last November. I've tried 4 voltage regulators, the one that came with the car (after market), an original VR from a 74 1.8l and two different models from Transpo. The issue is the same with all VRs, with the voltage jumping around as RPMs change. Today I started it and the voltage at the battery was 12:35 with the car running. Voltage did not change as the increase RPMs while the car was still parked. When I took it for a drive I saw it was over 14V then later it was over 16V. Voltage does lower to the expected amount (< 14B) when I turn the head lights on which puts more load on the battery. I've redone three grounds, the one above the transaxle in the back, the one under the relay board and the one under the fuse panel under the dash. Has anyone else experienced this?

[fixer34]

I've been unable to figure out why my charging voltage is so sporadic. Charging voltage ranges from 12.35 volts to 16+ volts. I first noticed this 2 months ago but it could have been going on since I got the car last November. I've tried 4 voltage regulators, the one that came with the car (after market), an original VR from a 74 1.8l and two different models from Transpo. The issue is the same with all VRs, with the voltage jumping around as RPMs change. Today I started it and the voltage at the battery was 12:35 with the car running. Voltage did not change as the increase RPMs while the car was still parked. When I took it for a drive I saw it was over 14V then later it was over 16V. Voltage does lower to the expected amount (< 14B) when I turn the head lights on which puts more load on the battery. I've redone three grounds, the one above the transaxle in the back, the one under the relay board and the one under the fuse panel under the dash. Has anyone else experienced this?

Check the belt and puleys. Loose/worn?
Next is to pull the alternator and have it checked/rebuilt.

[windforfun]

Speaking of voltage regulators, maybe yours is shot.

(IMG:style_emoticons/default/shades.gif) (IMG:style_emoticons/default/shades.gif) (IMG:style_emoticons/default/shades.gif)

[Spoke]

Did all 4 VRs give the same results? Exactly the same?

Does the GEN light come on when starting then go out for all driving?

With the engine running, lights on, measure the 3 voltages on the VR connector to chassis, not engine case.

D+ should be 14V
DF should hover 5-10V
D- should be zero volts

The charging system is quite simple but the components are buried in the car.

D+ and battery voltage and B+ should be identical.

Measure all to chassis, not engine case or battery neg.

[slapshot]

I've been unable to figure out why my charging voltage is so sporadic. Charging voltage ranges from 12.35 volts to 16+ volts. I first noticed this 2 months ago but it could have been going on since I got the car last November. I've tried 4 voltage regulators, the one that came with the car (after market), an original VR from a 74 1.8l and two different models from Transpo. The issue is the same with all VRs, with the voltage jumping around as RPMs change. Today I started it and the voltage at the battery was 12:35 with the car running. Voltage did not change as the increase RPMs while the car was still parked. When I took it for a drive I saw it was over 14V then later it was over 16V. Voltage does lower to the expected amount (< 14B) when I turn the head lights on which puts more load on the battery. I've redone three grounds, the one above the transaxle in the back, the one under the relay board and the one under the fuse panel under the dash. Has anyone else experienced this?

Check the belt and puleys. Loose/worn?
Next is to pull the alternator and have it checked/rebuilt.

The belt is tight and I'm able to turn the crank using the 22mm bold on the alternator pulley to set TDC for valve adjusts. Removing the alternator and having it rebuilt might be what I end up doing since swapping VRs and checking grounds does nothing.

[slapshot]

Speaking of voltage regulators, maybe yours is shot.

(IMG:style_emoticons/default/shades.gif) (IMG:style_emoticons/default/shades.gif) (IMG:style_emoticons/default/shades.gif)

I've tried 4. 2 are new.

[slapshot]

Did all 4 VRs give the same results? Exactly the same?

Does the GEN light come on when starting then go out for all driving?

With the engine running, lights on, measure the 3 voltages on the VR connector to chassis, not engine case.

D+ should be 14V
DF should hover 5-10V
D- should be zero volts

The charging system is quite simple but the components are buried in the car.

D+ and battery voltage and B+ should be identical.

Measure all to chassis, not engine case or battery neg.

All VRs react the same.
The charging light hasn't come on today even with the key on not running. I have seen it come on before.

Here's what I've got

Right after startup.
D+: 0V
DF: 0V
D-: 0V
B+: 12.6V

After a 1 minute drive parked at idle.
D+: 12.6V
DF: 7V
D-: 0V
B+: 13.7V

Parked reved @3000 RPMs
D+: 16V
DF: 3.1V
D-: 0V
B+: 15.9V

[windforfun]

Have you measured the alternator output vs. rpm & time?

[slapshot]

I went for a drive tonight and the battery guage in the car shows normal voltages with the lights on. Well, I'm not sure if normal is right but it stays between 12.5 and 14.0. With the lights out I see it go above 16 whitch is the last #.

[slapshot]

Have you measured the alternator output vs. rpm & time? Perhaps disconnect the hot side & see what it does without a load. It's just maybe a stupid suggestion. It's what I would do next. And I would measure it relative to the battery.

I'm not sure what you mean by "Have you measured the alternator output vs. rpm & time?". Is that different from what I did above? I haven't disconnected the alternater output yet. I've read not to run the car with the alternator disconnected. Maybe its fine for a short test.

[slapshot]

I figured out my charge light on the dash gauge. The issue was with the new VR I got today. The mounting plate on this one doesn't reach the screw holes in the relay board when plugged into the relay board. I had read in another thread that you can turn the VR around and plug the alternator cable directly into the VR. doing that broke the circuit to the charging dash light. It might have been the reason I got 0 volts on D+ and DF on initial start up for my test. I don't know. After I plugged the VR to the board as designed my charging light eliminated with the key on and car not running then turned off after started. My D+ voltage did jump over 14 while revving in my garage. I'll test again tomorrow when I don't need my lights to drive.

[Spoke]

I figured out my charge light on the dash gauge. The issue was with the new VR I got today. The mounting plate on this one doesn't reach the screw holes in the relay board when plugged into the relay board. I had read in another thread that you can turn the VR around and plug the alternator cable directly into the VR. doing that broke the circuit to the charging dash light. It might have been the reason I got 0 volts on D+ and DF on initial start up for my test. I don't know. After I plugged the VR to the board as designed my charging light eliminated with the key on and car not running then turned off after started. My D+ voltage did jump over 14 while revving in my garage. I'll test again tomorrow when I don't need my lights to drive.

OK without the GEN light in the circuit the VR may have a hard time starting up. The GEN light provides just that little bit of current needed by the armature to develop some magnetism to get the alternator started. This is called bootstrapping.

If you spin the motor fast enough even w/o the GEN light, a little bit of residual magnetism in the armature while spinning fast could get the alternator started.

Once started up, the alternator doesn't need the GEN light thus it's off during normal operation.

Your measurement of 16V is a problem. The battery voltage should never go much over 14V and unless loaded down with lights at low RPM, shouldn't go below 13V.

[campbellcj]

^ I didn't know about the operational details re alternator bootstrapping until just now, but just had this scenario happen as the Gen LED in my (old) custom Mark Surel quad-gauge failed. My mechanic was thinking using an LED vs incandescent bulb might interfere with proper charging system operations but it does seem to be working fine again with a new LED via NH Speedo and a new Hella VR.

[windforfun]

Have you measured the alternator output vs. rpm & time?

I'm not sure what you mean by "Have you measured the alternator output vs. rpm & time?". Is that different from what I did above? I haven't disconnected the alternater output yet. I've read not to run the car with the alternator disconnected. Maybe its fine for a short test.

Do not disconnect the alternator.

[Superhawk996]

Did all 4 VRs give the same results? Exactly the same?

Does the GEN light come on when starting then go out for all driving?

With the engine running, lights on, measure the 3 voltages on the VR connector to chassis, not engine case.

D+ should be 14V
DF should hover 5-10V
D- should be zero volts

The charging system is quite simple but the components are buried in the car.

D+ and battery voltage and B+ should be identical.

Measure all to chassis, not engine case or battery neg.

All VRs react the same.
The charging light hasn't come on today even with the key on not running. I have seen it come on before.

Here's what I've got

Right after startup.
D+: 0V
DF: 0V
D-: 0V
B+: 12.6V

After a 1 minute drive parked at idle.
D+: 12.6V
DF: 7V
D-: 0V
B+: 13.7V

Parked reved @3000 RPMs
D+: 16V
DF: 3.1V
D-: 0V
B+: 15.9V

If I were a betting man, I’d bet alternator armature brushes are worn out or sticking based on the readings right after start up.

Would also explain the erratic readings as you drive.

The other weird reading is the 16v @ 3000 rpm with DF at 3.1v. Seems like the alternator is being full fielded but with very little voltage on DF. Could potentially be two issues with both a bad alternator and a sticky voltage regulator?

The more I look at the numbers - a sticking voltage regulator could also account for the numbers you see at at start up if contacts between D+ and DF are open. If they are stuck open, and DF isn’t even making it to the armature until then contacts rattle around / come unstuck and then the alternator can be bootstrapped to life.

I’d start by getting a good Bosch voltage regulator in to it. The fact that you have 4 of unknown quality and history isn’t helping convince me it’s not the voltage regulator based on your measurements.

914Sixer has a used Bosch solid state on F/S and sounds like a couple other NOS units on the way which will seem pricey but will be better than cobbled aftermarket units that don’t fit right.

Do you know what kind of regulators you’re currently using are - solid state transistor or the original mechanical solenoid style? Original mechanical regulators are sometimes repairable by cleaning the contacts between D+ and DF if you’re inclined to try to troubleshoot a mechanical regulator.

http://www.914world.com/bbs2/index.php?showtopic=367286

Edit: just seeing this in context of initial readings after start

Yet another reason to stop screwing with aftermarket voltage regulators that don’t fit and may not work properly:

The more I look at your post(s) and the measurements - the more I’m leaning toward a bad voltage regulator regardless of what I said initially about armature brushes.

[slapshot]

Did all 4 VRs give the same results? Exactly the same?

Does the GEN light come on when starting then go out for all driving?

With the engine running, lights on, measure the 3 voltages on the VR connector to chassis, not engine case.

D+ should be 14V
DF should hover 5-10V
D- should be zero volts

The charging system is quite simple but the components are buried in the car.

D+ and battery voltage and B+ should be identical.

Measure all to chassis, not engine case or battery neg.

All VRs react the same.
The charging light hasn't come on today even with the key on not running. I have seen it come on before.

Here's what I've got

Right after startup.
D+: 0V
DF: 0V
D-: 0V
B+: 12.6V

After a 1 minute drive parked at idle.
D+: 12.6V
DF: 7V
D-: 0V
B+: 13.7V

Parked reved @3000 RPMs
D+: 16V
DF: 3.1V
D-: 0V
B+: 15.9V

If I were a betting man, I’d bet alternator armature brushes are worn out or sticking based on the readings right after start up.

Would also explain the erratic readings as you drive.

The other weird reading is the 16v @ 3000 rpm with DF at 3.1v. Seems like the alternator is being full fielded but with very little voltage on DF. Could potentially be two issues with both a bad alternator and a sticky voltage regulator?

The more I look at the numbers - a sticking voltage regulator could also account for the numbers you see at at start up if contacts between D+ and DF are open. If they are stuck open, and DF isn’t even making it to the armature until then contacts rattle around / come unstuck and then the alternator can be bootstrapped to life.

I’d start by getting a good Bosch voltage regulator in to it. The fact that you have 4 of unknown quality and history isn’t helping convince me it’s not the voltage regulator based on your measurements.

914Sixer has a used Bosch solid state on F/S and sounds like a couple other NOS units on the way which will seem pricey but will be better than cobbled aftermarket units that don’t fit right.

Do you know what kind of regulators you’re currently using are - solid state transistor or the original mechanical solenoid style? Original mechanical regulators are sometimes repairable by cleaning the contacts between D+ and DF if you’re inclined to try to troubleshoot a mechanical regulator.

http://www.914world.com/bbs2/index.php?showtopic=367286

Edit: just seeing this in context of initial readings after start

Yet another reason to stop screwing with aftermarket voltage regulators that don’t fit and may not work properly:

The more I look at your post(s) and the measurements - the more I’m leaning toward a bad voltage regulator regardless of what I said initially about armature brushes.

I didn't have a chance to look at it today.

The VR I just bought and have on it now is

https://www.amazon.com/dp/B09KSCGLZV?psc=1&...product_details

The one I bought last month is

https://www.amazon.com/gp/product/B09KSD9YH...=UTF8&psc=1

I have an original Bosch from a 74 1.8L. The one that was on it when I bought it was aftermarket. Its at the landfill now.

I'm leaning towards removing the alternator and see what the condition of the brushes are in. The alternator was replaced in 2010. If all looks good there, I'll go back to the VR.

[Superhawk996]

Just a heads up getting to alternator diodes and brushes isn’t easy. More often than not the alternator pulley is seriously tight on the armature shaft to the point that you will bend the pulley trying to remove it.

Of the regulators you posted links to the first appears to be solid state but shows some sort of adjustable potentiometer on the bottom - weird that a potentiometer would be left exposed like that. The second regulator looks to be more like mechanical solenoid based in a taped can.

Both made in China and I wouldn’t trust either of them to be working unless they were bench tested and verified to be working. Neither has any statistically significant user reviews to know how the quality of these units is.

Why the opposition to a decent Bosch unit?

The other thing that I’d verify is that all the spade terminals in the relay board and the alternator feed to the board are clean and tight. Loose connections, not making proper contact can lead to regulation problems. Are you absolutely sure the regulator is making positive contact with the terminals in the relay board?

[slapshot]

Just a heads up getting to alternator diodes and brushes isn’t easy. More often than not the alternator pulley is seriously tight on the armature shaft to the point that you will bend the pulley trying to remove it.

Of the regulators you posted links to the first appears to be solid state but shows some sort of adjustable potentiometer on the bottom - weird that a potentiometer would be left exposed like that. The second regulator looks to be more like mechanical solenoid based in a taped can.

Both made in China and I wouldn’t trust either of them to be working unless they were bench tested and verified to be working. Neither has any statistically significant user reviews to know how the quality of these units is.

Why the opposition to a decent Bosch unit?

The other thing that I’d verify is that all the spade terminals in the relay board and the alternator feed to the board are clean and tight. Loose connections, not making proper contact can lead to regulation problems. Are you absolutely sure the regulator is making positive contact with the terminals in the relay board?

Thanks for the info on the alternator, Sounds like I'd be getting into more than I want or should.

I'm not opposed to a Bosch VR. I just felt that with 4 VRs giving the same result I should look elsewhere. I'm going to PMB Performance tomorrow to get some wheel bearings and will buy the VR they sale. I will also ask if they are able to test my VRs.

My relay board isn't in perfect condition but I wouldn't say its in poor condition either. I think you make a great point with connections being a possibility. That's something I can work on.

[Spoke]

The VR I just bought and have on it now is

https://www.amazon.com/dp/B09KSCGLZV?psc=1&...product_details

@slapshot
@Superhawk996

I wonder what this potentiometer is for. Was there any information of how to set this pot?

Does yours even have this pot? Maybe this is a stock photo.

I have to imagine that there could be a gain setting in a VR to provide exactly the correct DF voltage given the voltage feedback at D+.

[Spoke]

The other weird reading is the 16v @ 3000 rpm with DF at 3.1v. Seems like the alternator is being full fielded but with very little voltage on DF. Could potentially be two issues with both a bad alternator and a sticky voltage regulator?

@Superhawk996

Yeah I noticed the low voltage at DF at high RPM too. Not quite sure what to make of it. I kinda looked beyond that assuming a high RPM armature would couple to the stator much more efficiently at high speed thus requiring less voltage at DF. Makes me want to start up my 914 and do this test at idle and 3k RPM.