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Discussion Starter #1
Recent acquisition. 75 Giulia Nuova Super 1300, ran great on way home, still runs great, but the alternator light is on. Checked output across battery, over 16 volts at 2500-3000 rpm. NOS voltage regulator installed, light remains on, any thoughts comments or suggestions. TIA, Farn
 

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I'm not sure I'm understanding the sequence of events.

- you measured over 16 volts across battery, at 2500-3000 rpm

- then you installed a NOS voltage regulator

- then you measured a voltage of ????? at the battery

- but the light remained on?

Do I have that right?

I assume your '75 Super has an alternator with an external regulator. If nothing changed after swapping regulators, I would next examine the harness between alternator and regulator. Those harnesses tend to fail, and an open connection might explain why changing regulators didn't fix things. Or your NOS regulator may be faulty.

Are you sure your voltmeter is OK? What voltage across the battery does it measure with the engine off? If the voltage increases with the alternator running (should go from ~12 at off to ~14 when running) then I'm puzzled why the light stays on (which leads me to believe that a wire may be broken in that harness I discuss above).

But you do need to do something. Excessively high voltage can damage the battery and anything with electronics (radio, electronic ignition).
 

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Discussion Starter #3
Saw the light, tested voltage across battery to see if alternator was not charging, it was overcharging, which lead me to believe faulty voltage regulator, swapped out the one that came with the car with NOS Bosch, light still on (I figured the voltage regulator was the culprit, apparently not) walked away as it is to hot at present, will check wiring when I get a chance. Car is not on the road at present, but am aware that overcharging isn't good for anything. Thanks, Jay
 

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Haven鈥檛 done much investigating into the issue yet, but with engine off, and not run for a day and a half I got 12.92 volts from the battery. I also discovered the alternator is of Paris Rh么ne manufacture, original voltage regulator is Paris Rh么ne as well. Just wondering about rebuilding alternator or would an Alfa Bosch unit bolt right in. Still need to check wiring, connections etc. before I commit to anything. Tia
 

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with engine off, and not run for a day and a half I got 12.92 volts from the battery
Sounds a bit high, though since you've been "super-charging" it with 16V, perhaps not too surprising.

I also discovered the alternator is of Paris Rh么ne manufacture, original voltage regulator is Paris Rh么ne as well. Just wondering about rebuilding alternator
I don't know much about Paris Rh么ne electricals - you may encounter difficulty getting that rebuilt here in the US. Was your car built for the US market? Your local independent electrical repair shop may have never heard of an Alfa (be prepared for: "Alpha Romero - who makes that?"), but will sure know Bosch.

would an Alfa Bosch unit bolt right in.
Yup.

But if you do source a replacement Bosch alternator, get one that fits a late-model spider (it will also bolt right in). The advantage is that it will have an internal regulator - makes it much more reliable. Minor modification to the wiring required (push the terminal attached to the wire to the warning light out of the alternator connector, clip off the wire that used to go to your old regulator, plug the terminal into the new alternator).
 

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Discussion Starter #6
Thanks Jay, it is a euro model, I too was surprised not to Robert Bosch's alternator when I looked. Paris Rohne is kind of like a well kept secret, I was concerned about if I did use a Bosch alternator would the harness for the old alternator fit the new one. Will dig in a little deeper before deciding on my direction. Thanks again!
 

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I was concerned about if I did use a Bosch alternator would the harness for the old alternator fit the new one.
Oh, you're right. I'm envisioning the Bosch harness, but your's might look different.

Still, if you use an internally-regulated alternator (e.g., one from a late '80's or newer spider or a Milano) the wiring shouldn't be an issue. I'm confident the Paris Rh么ne would still have the large-gauge wire that goes directly to the battery and a wire somewhere (either at the alternator or regulator) that goes to the warning light. And that's it - the other wires just interconnect the alternator and external regulator and you would be ditching those components.
 

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Discussion Starter #8
Hey Jay, just to update you, took your advice put in a rebuilt internal regulator bosch unit, hooked up power and the green wire, no light, normal output all good, thanks for putting up with me, appreciate it! Fran
 

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Now that Fran鈥檚 issue is fixed, I鈥檒l jump in with my similar but slightly different version of the problem.

A few days ago I noticed suddenly the alternator light came on and the fuel and oil gauges went off. A check across the battery terminals when running showed low charging. I changed the alternator with external regulator to a new Alfaholics 65A unit with integrated regulator.

Now, on initial startup (low idle), the alternator light is off, but as soon as revs come up the light comes back on. Fuel gauge and oil gauge are still out. So I guess we鈥檝e ruled out the alternator and regulator. Any other items to check that can influence the charging circuit?
 

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Now that Fran鈥檚 issue is fixed, I鈥檒l jump in with my similar but slightly different version of the problem.

A few days ago I noticed suddenly the alternator light came on and the fuel and oil gauges went off. A check across the battery terminals when running showed low charging. I changed the alternator with external regulator to a new Alfaholics 65A unit with integrated regulator.

Now, on initial startup (low idle), the alternator light is off, but as soon as revs come up the light comes back on. Fuel gauge and oil gauge are still out. So I guess we鈥檝e ruled out the alternator and regulator. Any other items to check that can influence the charging circuit?
Knowing which car you have would be a big help. Sounds as if you have a short on the circuit with that has the alternator warning light and gauges. #6 fuse on a Spider.
 
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