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Tcash
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telford dorr
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 Posted: Sun Nov 04, 2012 5:30 pm Post subject: Re: Charging System |
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All good stuff, except:
"Testing the Generator in the Car" section.
Don't do this - without disconnecting the Df wire between the generator and the regulator. There is a good possibility that the regulator voltage control relay contact set could be damaged. This is because it's possible (likely?) that the armature voltage will exceed the maximum voltage on the regulator relay, which will close and short the field winding (as it's supposed to do - see the "How the Generator Voltage is Safeguarded" section). This stops all field current, effectively shutting the generator off. Unfortunately, by jumping Df to D-, the voltage relay will also short the armature. This is not good at all for the voltage regulator's lifespan (especially if it's an electronic regulator).
Removing the Df wire from the regulator will allow the test to be run without damaging anything.
Even so, limit the test (as stated) to the minimum amount of time possible, to avoid generator damage from over-voltage.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
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Tcash
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| Posted: Sun Nov 04, 2012 8:05 pm Post subject: |
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Tcash
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| Posted: Wed Mar 27, 2013 11:29 am Post subject: |
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Thanks goes out to Telford
| telford dorr wrote: |
I concur. You have to treat the alternator / regulator / interconnecting harness as a 'system'. Failure of any one part will cause the 'system' to fail. It's either 100% OK, or it's not.
The best way to check out the system functionality is with a voltmeter. You should get 13.8 to 14.4 volts (typically) at the battery when the engine is at, say, 2000 rev/min. You should have approximately the same voltage on the battery side of the ALT light, and at the alternator 'D+' terminal. The alternator rotor voltage, measured between D- and Df, will typically be high at idle, and decrease with increasing engine speed. The alternator should pull no current from the battery when the engine is stopped and the key is off.
If testing shows that the 'system' isn't functioning properly, the best course of action is to disassemble and remove the entire 'system' from the bus and test it externally; on the bench (if you have a motor of some kind to spin the alternator), or at your FLAPS which offers testing service. If you do the latter, take the entire system (including the battery and a test light to sub for the ALT light on the dash [as others have mentioned, required for the system to function]) and have it tested as a system. If it doesn't pass, then test individual parts until you find the bad one(s). You're not done until the entire system passes functional testing. Do not settle for 'deductive' testing (since everything else seems to be good, then this untested part must be bad...)
At this point, you know that you have good parts. If, after re-installation, you still have issues, and you've checked the installation for shorts, etc., then the problem must lie elsewhere in the bus wiring.
The bus wiring may be quick-checked by disconnecting the regulator wiring. Then, with the key 'on', the ALT light should be off. Grounding the blue wire at the regulator should cause the ALT light to illuminate.
Note: in the schematic above, connect the test light between the 'to ALT light' wire and the 'to battery' wire for testing. Connect the battery between 'to battery' ('+' terminal) and ground ('-' battery terminal), where 'ground' is the frame of the alternator. |
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telford dorr
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| Posted: Wed Mar 27, 2013 11:35 am Post subject: |
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Great photo collection! They should be put as a reference in "Technical" somehow. Everett???
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
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old DKP driver
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| Posted: Wed Mar 27, 2013 7:09 pm Post subject: charging system |
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Telford,
The information & Pictures Are from 'Late Model 68-Up type 1 FORUM
FAQ "STICKY"
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telford dorr
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| Posted: Wed Mar 27, 2013 7:39 pm Post subject: |
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That's good, but Bus people may never go there. I think they're useful enough to have their own subsection in "Technical".
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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Tcash
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Location: San Jose, California, USA
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Tcash
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Location: San Jose, California, USA
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| Posted: Tue Feb 18, 2014 9:29 pm Post subject: Mechanical Voltage Regulator Internal Wiring Schematic/Color |
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Thanks to Telford Dorr
Diagram of how a voltage regulator is wired internally
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Tcash
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Tcash
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Joined: July 20, 2011
Posts: 12844
Location: San Jose, California, USA
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| Posted: Wed Jun 29, 2016 11:46 am Post subject: 38 amp generator install |
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To link to this post
| Code: |
| [url=http://www.thesamba.com/vw/forum/viewtopic.php?p=8131698#8131698]38 amp generator install[/url] |
Thanks to all that posted information.
This is the assembled components needed to install a 38A generator.
--38A generator 211 903 031 D 13mm longer. Bosch short number GR17.
38A generator on Left is 13mm longer than 30A generator on Right.
--38A generator Pulley 211 903 109 cast iron.
Left: 30A pulley is pressed metal. Right: 38A pulley front half is cast iron and has more of an offset.
Note: Pulley back half has a balancing weight and the profile is different.
Note: Cast iron, hub and pulley are one piece.
Note: The pulley is cast iron and brakes easily. So when using a screw driver in the notch, the pulley will break if you apply too much force. If needed use an air gun to zip the nut off while holding the pulleys in a gloved hand.
What ever you do. Do not be prying to hard on the sides of the pulley with screw drivers. Spray it with some rust penetrant and apply heat to get it off.
--Fan
(Non-Doghouse Style) 131 119 031 32mm wide.
(Doghouse Style) 113 119 031B 35mm wide. Can be up to 37mm.
--38A generator Fan Cover
outer 211 119 259
inner 211 119 261
Note: the fan covers are not flat but dished (dimpled, bowled) to accept the 13mm added length of the 38A generator. The dimple faces the fan shroud, the front of the vehicle.
Note: wrong 30A fan hub installed.
Note: 38A fan cover. The cover is concave (bowl) shaped. To help allow for the added 13mm length of the 38 amp generator.
Note: 30A fan cover. The cover is convex (hat) shaped.
--38A generator pulley Special Washer (Spacer) 211 903 183 11mm wide.
--38A generator Fan Hub 211 119 123
Note: 38A Hub looks like a Top hat, not offset between the hub and Gen.
--Hub Carrier Plate 111 119 131
--Shim 0.5 mm 111 903 131 A
--38A generator: Voltage Regulator 211 903 803 E
Note: 30A and 38A regulators look the same. So look for the 38A stamping near the mounting hole.
--Test Data
Cut in speed 1600 rpm
Cut in Volts 12.5-13.2v
Reverse Current 5-11.5A
Regulating Volts (no load) 13.5-14.2v
Regulating Volts (under load) 12.9-13.6v
Load current 35A
Workshop Bulletin No. E of 13 August 1968
http://www.jerseylooker.com/FicheDump/EarlyBaywindow/EarlyBay-9.html
http://www.jerseylooker.com/FicheDump/EarlyBaywindow/EarlyBay-1.html
Last edited by Tcash on Fri Jul 28, 2017 4:08 pm; edited 2 times in total |
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Tcash
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| Posted: Wed Jun 29, 2016 3:19 pm Post subject: 38 amp Voltage Regulator 211 903 803 E |
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--Test Data
Cut in speed 1600 rpm
Cut in Volts 12.5-13.2v
Reverse Current 5-11.5A
Regulating Volts (no load) 13.5-14.2v
Regulating Volts (under load) 12.9-13.6v
Load current 35A
--38A generator: Voltage Regulator 211 903 803 E
Note: 30A and 38A regulators look the same. So look for the 38A stamping near the mounting hole.
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telford dorr
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Location: San Diego (Encinitas)
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| Posted: Wed Jun 29, 2016 4:40 pm Post subject: Re: Charging System |
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checking in...
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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Tcash
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Location: San Jose, California, USA
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| Posted: Wed Jun 29, 2016 5:02 pm Post subject: Re: Charging System |
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| telford dorr wrote: |
| Filthy Dub wrote: |
| How would I be able to tell if the voltage regulator is kaput? |
The general method is to replace it. If the new one works, the old one was bad. [The problem with this method is if you have a 38 amp regulator, you'll likely have to substitute a 30 amp unit, as replacement 38 amp units are rare. If you substitute a solid state version, be aware the case shell is at 12 volts, so don't short it to ground accidentally.]
However, if you have a variable voltage DC power supply (a 'dumb' battery charger and a Variac will also work), you can easily bench-test them. On the regulator, you connect a test light between D+ and Df, and connect the power supply between D+ and case ground. You now slowly increase the power supply voltage. As it reaches around 14 volts, the test light will switch from solid on to flickering or off. If the regulator is a mechanical type, it will start buzzing. This is the regulation point. Don't stay at this voltage level too long, as there's a resistor on the bottom of mechanical regulators that will start to get hot.
Other tools / info: generator / alternator test stand:
Regulator internal wiring:
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| telford dorr wrote: |
| Tcash wrote: |
So this would test the (Current/Voltage regulator)
How would you test the (Cutout relay)? |
Connect the test light from B+ to ground. As you increase the voltage on D+, you'll reach a point where the cutout relay will pull in, lighting the light. Decreasing the voltage should cause the cutout relay to drop out, turning off the light. [Note this is not a complete test, as the cutout relay normally drops out from reverse current flow from the battery into the generator. You'd need an actual battery and voltmeter connected to B+, plus a power supply that can sink current (not common), to test this accurately.]
| Quote: |
| I found this on youtube. It is testing an alternator regulator. But shows the test procedure. Telford is this adequate for demonstration purposes? |
Yes, for solid-state regulators (other than the 15 volt regulation point - a bit high...) Mechanical regulators seem to vibrate the contacts at the trip point rather than a nice clean switch. But yeah, it's adequate. |
| telford dorr wrote: |
| Tcash wrote: |
Another question, a variac is expensive.
What specifications would be needed? |
Yeah, they are - but a good one will last a lifetime. Watch ebay - stuff comes up periodically.
130 volt 5 amp would be ideal. For purposes of this specific test, 1.5 amps would be enough.
| Quote: |
| Would one of these fit the bill? |
All are a bit light (for general purpose use). You need 0->15 volts at 4 amps minimum for generator testing and ignition testing. Again, I'd look on ebay for used adjustable lab power supplies. Mine is an old HP unit ('70's vintage) that's good for 24 volts and 4 amps.
If you already have a Variac, a 'dumb' battery charger is generally good for 10 amps, and can be had pretty cheap (especially used), as everyone wants 'smart' chargers now (which are definitely better for the battery, and won't fry your electronics, like the old dumb chargers would...)
And then there's serious overkill (30 amp Variac, 160 amp dumb charger):
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Tcash
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| Posted: Wed Jun 29, 2016 5:09 pm Post subject: 38 amp voltage regulator testing |
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So looking at the specs.
--Test Data
Cut in speed 1600 rpm
Cut in Volts 12.5-13.2v
Reverse Current 5-11.5A
Regulating Volts (no load) 13.5-14.2v
Regulating Volts (under load) 12.9-13.6v
Load current 35A
Reverse Current is 5-11.5A
Could you hook up
10A battery charger>battery>B+
To fool the Cut out relay in to thinking it had reverse current?
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telford dorr
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| Posted: Wed Jun 29, 2016 8:57 pm Post subject: Re: Charging System |
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Haven't tried it that way, but (on paper) it should work fine (unless you found a stubborn one that wanted the whole 11.5 amps of reverse current to drop out - but the probability of that is low...)
What's going on with that is as follows: note on the regulator drawing that the cut-out relay has two coils. The first coil has generator voltage applied to it, to ground. This is the coil that pulls in when the generator voltage is roughly the same as the battery voltage. Once that relay closes, charging current (from the generator to the battery) flows through the second coil, which increases the field strength, locking that relay on.
Now when the engine is stopped, as it slows down, it reaches a point where the generator output voltage falls below the battery voltage, When this happens, current now flows the other way, from battery to generator, through this second winding. The generator has now become a motor, trying to turn the engine. This reverse current flow counteracts the first coil, canceling its magnetic field, which allows the relay to open, disconnecting the battery from the generator. This stops the generator from trying to be a motor, which it really doesn't like, considering the load it's trying to turn.
Fortunately, this shutdown sequence happens really fast (within a second or two), thus any undesirable side effects are minimized - unless the cut-out relay sticks. Then the battery dumps itself into the now stalled generator, causing it to release its purple smoke and melting the armature into a lump . Now you need both a new regulator and a new generator.
These days, this whole mechanical fast dance has been made obsolete by the substitution of solid state diodes (in parallel) for the cut-out relay. Because they switch pretty much instantly, there's NO reverse current from the battery to the generator, ever. This pretty much makes a solid state regulator operationally superior to its mechanical cousin. With one exception: when it fails out in the middle of nowhere, it's dead and not coming back. With the mechanical regulator, you might be able to sand up its contacts with some 220 grit, and get yourself back on the road...
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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Tcash
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Joined: July 20, 2011
Posts: 12844
Location: San Jose, California, USA
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| Posted: Thu Jun 30, 2016 9:01 pm Post subject: Re: Charging System |
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Thank you
Let me ask you. Why would vendors be advertising the solid state voltage regulator for 38A generators?
Tcash |
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Tcash
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Location: San Jose, California, USA
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| Posted: Thu Jun 30, 2016 9:09 pm Post subject: Voltage regulator |
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This video does a good job explaining the Voltage regulator operation.
Link
Note the Voltage regulator and Current limiter are built into one relay on our regulators.
As depicted as the Current/Voltage Regulator in the picture.
Last edited by Tcash on Thu Jun 30, 2016 9:26 pm; edited 1 time in total |
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telford dorr
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Location: San Diego (Encinitas)
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| Posted: Thu Jun 30, 2016 9:19 pm Post subject: Re: Charging System |
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| Tcash wrote: |
| Let me ask you. Why would vendors be advertising the solid state voltage regulator for 38A generators? |
Because (1) it will work, and (2) they hope the average user won't notice that they're only getting 30 amps because it's generally enough to get the job done. Or they might not even know this. They're parts salesmen, and a sale is a sale...
Same as the fact that you can drive your bus without getting full throttle because the cable is misadjusted.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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Tcash
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Posts: 12844
Location: San Jose, California, USA
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| Posted: Thu Jun 30, 2016 9:31 pm Post subject: Re: Charging System |
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Telford
Could you wire in a resister on the current relay to increase the amps say from 30A to 35A?
Or would it require rewinding?
Thank you
Tcash |
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