Alternator question., Not Charging. Options

[Tdskip]

I think malcolm2 is right -- and I don't think even Bosch rebuilds are immune. That's one of the reasons I ended up doing an alternator swap using a new manufactured alternator from a company with a good reputation.

I’ve gotten bad rebuilt ones, not unheard of unfortunately.

[Gatornapper]

Ok, friends - this thread has been very helpful, but my situation is a bit different from any listed here.

New gel battery, resting voltage, 12.6. Ground connections good.

Gen Light:

* Comes on very bright as it should with ignition on, engine not running.
* Completely goes out when engine is running. No, it's not even dim.
* Comes on dim when headlights are on.
* MAXIMUM charging voltage with engine running, no loads except ignition, is 12.2, very slowly drops over time; drops to 11.9 with headlights on, slowly continues to drop over time. Strong battery lets me drive for 30 min with headlights on.
* Gen light never comes on bright when engine is running; only when engine is off.

So, alternator is not charging - OR, VR is not adjusting voltage for load.

DID THE D+ TO DF Jumper TEST: at rpm, voltage at battery jumps to 16.9 to over 17.

So alternator is good, right?

Purchased NOS regulator from great fellow member here.

My original VR and the NOS VR both perform exactly the same....no charging. Gen light is OFF unless I turn headlights on, then is dim. Engine running with either VR is 12.2, and seems to stay there for some time.

So it seems to me that there is some charging going on - just not enough.

Been doing auto electrics for almost 50 years and never seen this one. Never seen a VR/alternator problem before I couldn't diagnose and repair.

Oh - would the wrong size Gen lamp cause this? Seems the correct size to my by the way it is functioning......but hey, what do I know?

Oh- ordered a cheap new VR from Rock Auto to use as a test unit, but it won't be here for 10 days - like to have the car ready for the local 9/14 - 914 event.

TIA,

GN

[Spoke]

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V
D- to chassis ground. Should be 0V
DF to chassis ground. Should be 5-9V
Battery POS post to chassis ground. Should be 14V
Battery NEG post to chassis ground. Should be 0V

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

When did this start happening? Did you do any work on the car?

[Gatornapper]

Only work on car had nothing to do with electrical. Problem has been there since I first ran engine a couple months ago - I've not been driving the car much and have been focused on other more important mechanical needs - like brakes.

Should I read these voltages at the VR pins as well? Or only the alternator plug? BTW, I cleaned both after the NOS VR did not produce proper voltage. Seem the relay board has to be good to get the 17v with D+ & DF jumped, right?

Car sat for almost 14 years......

Thanks for all these voltages to check - will do tomorrow.

GN

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V
D- to chassis ground. Should be 0V
DF to chassis ground. Should be 5-9V
Battery POS post to chassis ground. Should be 14V
Battery NEG post to chassis ground. Should be 0V

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

When did this start happening? Did you do any work on the car?

[914Sixer]

Do you have a spare relay board to swap out?

[Spoke]

Should I read these voltages at the VR pins as well? Or only the alternator plug? BTW, I cleaned both after the NOS VR did not produce proper voltage. Seem the relay board has to be good to get the 17v with D+ & DF jumped, right?

The voltage can be measured with the alternator plug connected to the relay board as in normal operation thus you'll also be measuring the VR pins. The nice part about these measurements is you don't have to set up anything difficult, just measure the voltages at the plug WRT chassis ground.

About the relay board, I have heard of guys having issues with the relay board because the VR or alternator plug pins pushing through to short out to ground or whatever is below the pins. Not sure how to test these. Maybe someone can chime in who has faced this issue.

[Gatornapper]

I have quite a bit of experience with circuit boards, so if our voltage read-outs don't help, I can trouble-shoot the relay board too.......

GN

About the relay board, I have heard of guys having issues with the relay board because the VR or alternator plug pins pushing through to short out to ground or whatever is below the pins. Not sure how to test these. Maybe someone can chime in who has faced this issue.

[Gatornapper]

Spoke -

Ran tests tonight after 1 hour drive, so nominal battery voltage at time of test was 12.2 v, not my normal 12.6

Results of Lights Off in Blue; Lights ON in Red. All readings to chassis ground from VR pins.

So what does this tell you? Clearly something major is wrong as the DF voltages are no different from the D- voltages. But when D+ and DF were jumped, battery voltage was about 17v....

Bad relay board? No, do not have another....

TIA,

GN

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V 11.73v 10.89

D- to chassis ground. Should be 0V .015v -.004v

DF to chassis ground. Should be 5-9V .015v-.004v

Battery POS post to chassis ground. Should be 14V 12.2v
Battery NEG post to chassis ground. Should be 0V 0v

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

[904svo]

Just a WAG, measure the voltage between the alternator and the engine case with the engine running. There should be less than 1 volt. If its over 1 volt you have a grounding problem.There is a problem between the alternator and the engine case, there
should be a ground strap between the alternator and the engine caseto correct this problem.

[Spoke]

Spoke -

Ran tests tonight after 1 hour drive, so nominal battery voltage at time of test was 12.2 v, not my normal 12.6

Results of Lights Off in Blue; Lights ON in Red. All readings to chassis ground from VR pins.

So what does this tell you? Clearly something major is wrong as the DF voltages are no different from the D- voltages. But when D+ and DF were jumped, battery voltage was about 17v....

Bad relay board? No, do not have another....

TIA,

GN

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V 11.73v 10.89

D- to chassis ground. Should be 0V .015v -.004v

DF to chassis ground. Should be 5-9V .015v-.004v

Battery POS post to chassis ground. Should be 14V 12.2v
Battery NEG post to chassis ground. Should be 0V 0v

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

I assume the GEN light is off? It looks like there is no activity from the VR. DF drives the alternator armature and with 0V on DF thus 0V on the armature, the alternator is technically off and not running. You might want to check the resistance from the VR pins to the alternator plug just to make sure DF connects to DF, D+ to D+, and D- to D-.

If the VR pins to alternator plug resistances are good (0 ohm), then I would suspect the VR.

[Gatornapper]

Thanks for the idea - I'll do that. But previously I've checked all grounding connections and they are all good. Completely refurbished the one from the battery negative terminal to the chassis......

Another good point to measure is from the alternator mounting strap to the chassis and to the engine case while running.....I'll do that one too. All should be way less than 1 volt.....really zero.

GN

Just a WAG, measure the voltage between the alternator and the engine case with the engine running. There should be less than 1 volt. If its over 1 volt you have a grounding problem.There is a problem between the alternator and the engine case, there
should be a ground strap between the alternator and the engine caseto correct this problem.

[Gatornapper]

Spoke - yes, GEN light is OFF until I turn on headlights, then on, but very dim.

I will check for zero resistance between the VR pins and the alternator pins -

Thank you.

If all is well with the relay board, I have a bad VR that came with car and a bad NOS one I just bought from a forum member - who will refund my money if I want. First I want to make sure the NOS one is bad as well.

AND I have a cheap (Chineses I suspect) one coming next week from Rock Auto I got just for a point of reference.

Thanks!

GN

Spoke -

Ran tests tonight after 1 hour drive, so nominal battery voltage at time of test was 12.2 v, not my normal 12.6

Results of Lights Off in Blue; Lights ON in Red. All readings to chassis ground from VR pins.

So what does this tell you? Clearly something major is wrong as the DF voltages are no different from the D- voltages. But when D+ and DF were jumped, battery voltage was about 17v....

Bad relay board? No, do not have another....

TIA,

GN

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V 11.73v 10.89

D- to chassis ground. Should be 0V .015v -.004v

DF to chassis ground. Should be 5-9V .015v-.004v

Battery POS post to chassis ground. Should be 14V 12.2v
Battery NEG post to chassis ground. Should be 0V 0v

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

I assume the GEN light is off? It looks like there is no activity from the VR. DF drives the alternator armature and with 0V on DF thus 0V on the armature, the alternator is technically off and not running. You might want to check the resistance from the VR pins to the alternator plug just to make sure DF connects to DF, D+ to D+, and D- to D-.

If the VR pins to alternator plug resistances are good (0 ohm), then I would suspect the VR.

[Gatornapper]

Re: VR not working.

Both VR's I have get very hot - too hot to touch. So it seems that they are trying to work - lot of activity going on electrically to produce all that heat......

[Olympic 914]

Re: VR not working.

Both VR's I have get very hot - too hot to touch. So it seems that they are trying to work - lot of activity going on electrically to produce all that heat......

I had two original regulators that were tested as good at a auto electric shop and both of them would get hot when running. That may be why there is a hole in the relay board under the regulator, to let some air get in there.

I purchased a solid state regulator from BERU. and it works perfectly and does not get hot. you have to modify the mounting holes on the BERU unit and trim the plastic relay board cover for it to fit but when mounted you can't see the modification to the cover.

I think the BERU unit was $25-30

[Gatornapper]

Thanks - would like to get one....

Checked BERU's site, cannot get to where I can purchase a unit......entered United States, and my zip code - got nothing......

I had two original regulators that were tested as good at a auto electric shop and both of them would get hot when running. That may be why there is a hole in the relay board under the regulator, to let some air get in there.

I purchased a solid state regulator from BERU. and it works perfectly and does not get hot. you have to modify the mounting holes on the BERU unit and trim the plastic relay board cover for it to fit but when mounted you can't see the modification to the cover.

I think the BERU unit was $25-30

[euro911]

Typically can't purchase products from companies' web sites ... need to purchase items from retail vendors

https://www.autohausaz.com/pn/12181365-9016...hgaAiXcEALw_wcB

[Gatornapper]

Thanks Mark.

Typically can't purchase products from companies' web sites ... need to purchase items from retail vendors

https://www.autohausaz.com/pn/12181365-9016...hgaAiXcEALw_wcB

[Gatornapper]

Ok, test results:

Relay board not the problem......zero resistance between the D+, D-, and DF at the VR contacts and their matching points at the cable to the alternator end. No corrosion or even dust at any of the contact points - but then I had cleaned them with electrical contact cleaner anyway.

Also, voltage between battery ground and engine while running is .007 volt......essentially nothing.

Ran separate ground from engine to chassis, no change in anything.

Only thing left is the VR as far as I can see things......

Long wait until next Tuesday.

GN

[jcd914]

Maybe I missed in the thread but did you check voltage between the alternator body and the engine case? Should be zero.
The alternator grounds to teh engine through the mounting to the engine, unless someone has added a ground strap.
There have been a few cases of painted or powder coated alternator bodies and/or mounting brackets that were preventing a good ground for the alternator.

Good luck

Jim

[Spoke]

Re: VR not working.

Both VR's I have get very hot - too hot to touch. So it seems that they are trying to work - lot of activity going on electrically to produce all that heat......

Just to check: both VR's get very hot but both do not work and no charging is going on, correct? No charging means you see less than 12.6V while running.

It is odd that 2 VR's both do the same thing (get hot) but don't work. However when you short DF to D+ you get full charging from the alternator.

One more thing to check with engine off, check: remove the VR and disconnect the alternator cable. Then check resistance between D+ to DF, D+ to D- and D+ to D-. Just make sure there are no shorts on the relay board. All should be infinite.

Also measure resistance D+ to chassis; DF to chassis; and D- to chassis. All should be infinite although D+ might show some resistance as D+ is connected to the GEN bulb and to stuff on the other side of the bulb.

Again looking for shorts to ground. Just want to make sure there are no shorts on the relay board.