Voltage regulator

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x_atlas0

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Hello, everyone.

I think I toasted my voltage regulator in a moment of stupidity, so I am on the hunt for a new one. This is the external type, since the PO seemed to have the alternator rebuilt, rather than upgrading to a new style unit. I have seen one on Ebay that looks like it would work, it has the right plug and everything. It is also 60$, and I have a recipt from the PO when he got a new regulator in the early 90s for 15$. So, I know there must be a btter price out there. Any suggestions?

Alternatively, I could make my own. I am pretty handy with a soldering gun, and I could get some voltage regulators as samples from guys like Maxim or Dallas semiconductor.
 
Geez...

you want a better price than $15 for a regulator?!

I think I paid that for the reg on my VW bug, back in the 70s.

Pretty small item to scrimp on. For less than $15, you can get a used reg in unknown condition and if it works, fine, if not, then it's not worth the postage you'll pay to get another.

That said, if you want one of my old ones I'll send it for five bucks, you pay shipping. Will it work? Maybe. For another five I'll test it in my car and tell you it worked at the time. Have we got a deal?
 
Re: Geez...

you want a better price than $15 for a regulator?!
Click to expand...

I think he wanted a better price than $60.

X, go to your local import parts store and ask for the Bosch VR for a 70's Porsche 911. They're about $35, and it's the same as the BMW part.
 
Regulator

my bad, misread the cost in the original post. Still have the used regulators though ^)

please to 'scuse my haste.
 
Ok, it isn't the regulator. I have tried three, including one I made, and it didn't make a lick of difference. So, I guess my moment of stupidity went so far as to burn the brushes off the alternator. Since 55A alts. are rather tricky to come by, will installing a higher-rated unit (say, 90A) damage anything? Any complications involving switching to an internally-regulated unit?
 
It looks like a 65 amp alternator from an E12, E23, or E24 should bolt up and it has an internal regulator - minor wiring change.

I have a used coupe one if you need it.
 
What wiring changes do I have to make if I switch to an internal regulator?

Although, I suppose it won't do anything to have two regulators in series, if I want to keep the wiring pretty much stock.
 
Upgrading the alternator is not only not a problem, it's a great idea. The stock alternator puts out only barely enough amps to keep the car running. Using the lights, wipers and heater fan all at the same time is likely pulling enough amps to draw down your battery, given the increased resistance of 30 year old wiring. The 65a from the e12 will drop right in, and even the 90a and larger alternators from the late e28's and e23's will work if you use the associated mounting bracket (these will NOT fit the original bracket).

The wiring change is easy. You hook up the big red battery wire to the +ive terminal on the alternator, and then connect the wire from the charge light to the D+ spade on the alternator. If memory serves me, that is the green wire that goes to the external voltage regulator. You should check the wiring diagram, my memory is notoriously unreliable.

Unless you are building a 100 point concours car, I'd chuck the external VR and wiring in the bin. The internal (or more accurately, alternator-mounted) VR's are cheap and widely available.
 
The current (no pun intended) wiring would be:
B+ to battery
D-, DF, and D+ to voltage regulator
Since the regulator wold be internal, you would just need to connect the D+ from the alternator to the D+ wire connection that would go to the external regulator - that branches off to the idiot light on the dash - and leave the rest of the wires alone. I am working off the wiring diagram and assuming that the body of the alternator is the ground.
 
Tony and I must have been typing at the same time, the wire according to the diagram is blue.
 
Ok, I picked up a rebuilt E12 65A alt, with an internal regulator. I made a connector that links the alt to the original plug, connecting the D+ on the alt to the D+ node on the connector. The idiot light seems to be working, as it is slightly lit when the car is first started, but then goes off when I give it any gas at all, then remains off. However, while driving it around today, it was acting very much like it had no power. The radio kept shutting off and restarting, which means the voltage dipped below safe levels.

I don't know what is up. Any hints?
 
Ok, I jury-rigged a voltmeter up to the battery so I could see what was happening. The alternator is simply not charging the battery. It is a rebuilt alt, with a new voltage regulator, and the idiot light is off. I don't understand it. Help would be appreciated.
 
Do one thing before you pull the alt and take it back for exchange -- test the charge lamp to be sure it works. If it is burned out, your alt will not charge the battery. I know it sounds crazy, but it's true.

If the bulb is good, you got a bad alt. Have the rebuilder give you another.
 
I had to get my 73 3.0cs alternator fixed and found 73 capri uses the same alternator. Parts for a 73 capri is easier to get. The regulator may also be the same part.
 
Ok, I've been tinkering wih this problem for the last few days on and off, since I stil can't get the dang thing working right. The alternator is spinning, I have the external voltage rgulator bridged, and the output of the alt (D+) is going to the exact same spot it used to on the stock alt. The idiot light seems tobe functioning as it should, meaning on whenthe key is in run with the car off, on when you start the car, and off when the engine is running. When the car is running, the voltage sems to be about 12.05V at idle. If I goose it, the voltage drops to ~11.8V then returns to normal.

At this point, I'm about ready to try and rebuild the original, if I can find rebuild kit and some directions.
 
Ok, I bought another alternator, more like the original. It has external brush holders and an external regulator. That seems to work, raising the voltage to ~14.
 
Ok, new problem. On my way home from work, the old external regulator went legs up. This time, I know it is the regulator because the bypass test works. (jumping the pins in the connector turns off the idiot light) I ordered a new rgulator, but it isn't working. It is an ebay regulator, so I suppose the next step is the OEM part. I also subbed in a much older mechanical regulator I had laying around, and it worked for about 30 seconds before malfunctioning. When I removed it, it was exceedingly hot.

Any ideas this time, guys? I'm ordering the OEM part, but if that fails, I am sorta out of ideas.
 
Sounds like you have had multiple problems, my sympathy

1... Your "new alternator" with the low voltage output could be due to several factors including . Brushes worn. Internal voltage regulator stuffed. Diode failure, poor earthing.
2... When you replaced it with one that uses the external regulator, which you "blew up" it sounds like that regulator was not regulating, plus it was not shedding the excess load, in terms of amps. Again multiple reasons for this but a bad earth (ground) will not help.

I would make sure that if your mixing and matching that an external regulator is capable of handling the maximum alternator output in terms of amps. For example, a 45amp regulator will rapidly be destroyed if you use it in conjunction with 75amp unregulated alternator.
I would suggest that you take both your alternators to a good auto electrician's shop where they can put them on a test rig and check thier functionality and output. That way you will really know what you have!
HTH
Malc
 
Sounds like you have had multiple problems, my sympathy

1... Your "new alternator" with the low voltage output could be due to several factors including . Brushes worn. Internal voltage regulator stuffed. Diode failure, poor earthing.
2... When you replaced it with one that uses the external regulator, which you "blew up" it sounds like that regulator was not regulating, plus it was not shedding the excess load, in terms of amps. Again multiple reasons for this but a bad earth (ground) will not help.

I would make sure that if your mixing and matching that an external regulator is capable of handling the maximum alternator output in terms of amps. For example, a 45amp regulator will rapidly be destroyed if you use it in conjunction with 75amp unregulated alternator.
I would suggest that you take both your alternators to a good auto electrician's shop where they can put them on a test rig and check thier functionality and output. That way you will really know what you have!
HTH
Malc
Click to expand...

Yeah, the whole charging system has gone nuts since I stupidly installed the battery backwards. (truly a brain-cloud moment)

The rebuilt alt, I think, has bad grounding, since it is freshly rebuilt, with new brushes, and a new regulator. The original plug only connected at one prong, rather than 3, so I think that had something to do with it. The externally regulated one fit perfectly, so that means it must be either a 55 or a 65 amp unit.

As for the dead regulator, I drove the car to work without incident, everything looked normal. I fired up the car for the return trip, heard a pop, and noticed the voltage was low. It wasn't a new regulator, though, so who knows how old it was.
 
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