I believe my mechanical voltage regulator has gone out. When I measure the voltage across the battery while running, the reading is erratic. It changes so fast I can't get a steady measurement. Is this normal? I sometimes see high numbers flash by, 15, 16 and higher.

I'm thinking to switch to an electronic regulator. Is this a straight swap with no other mods required?

Hi there,
the reading from a regulator should be between 14.2 and 14.4 Volts.
A fully charged battery should be 13.2 V so there is at least a 1 V charging "Head". Any more than this can damage the battery and/or blow electrical devices.
If you are getting 15/16 V then the regulator is malfunctioning.
I can't give a simple answer to the electronic conversion as it is not something I have done on a Fiat 500 (my son's car).
The Green Spark Plug do replacement regs but these are mechanical.
Richard

Well, I was really hoping it was just a simple swap Oh well, guess I'll go back with a mechanical reg.

Texas500 said:

Well, I was really hoping it was just a simple swap Oh well, guess I'll go back with a mechanical reg.

Click to expand...

Or swap to an alternator with a built in VR. That way you get more capacity and an electric regulator.

cheers, Steve

stevehg said:

Or swap to an alternator with a built in VR. That way you get more capacity and an electric regulator.

cheers, Steve

Click to expand...

Trust me, I thought about it. Thing is, my 500D is unmodified (except for the Pertronix ignitor). It carries an 'ASI Gold Plate', has original plates, and original libretto. I need to keep it as close to original as possible.

The original regulator has served your car well for about 50 years then?
A new mechanical one should be OK.
The one on my car didn't move for 40 years but worked first time without any attention at all!
Keep it simple and don't swap for electronic.

PS. You can get them repaired but obviously, you won't easily find a specialist.

Texas500 said:

Trust me, I thought about it. Thing is, my 500D is unmodified (except for the Pertronix ignitor). It carries an 'ASI Gold Plate', has original plates, and original libretto. I need to keep it as close to original as possible.

Click to expand...

Makes sense. It should be possible to gut the mechanical one and fit inside an electronic one with the right ampage. Probably the best way would be to fabricate your own back plate. That way you get the original look, with an updated regulator.

Or as Peter suggests, get a mechanical one again. I have an original working one here you can have, that came from my 1971 500.

cheers, Steve

stevehg said:

Makes sense. It should be possible to gut the mechanical one and fit inside an electronic one with the right ampage. Probably the best way would be to fabricate your own back plate. That way you get the original look, with an updated regulator.

Or as Peter suggests, get a mechanical one again. I have an original working one here you can have, that came from my 1971 500.

cheers, Steve

Click to expand...

Hey Steve, if that mechanical regulator is just take up space, I'll gladly take it off your hands

Texas500 said:

Hey Steve, if that mechanical regulator is just take up space, I'll gladly take it off your hands

Click to expand...

Sure, let me find it tomorrow, and PM your address in Italy when you get a chance and I'll get a courier quote for you. You can then decide whether it's cheaper to source locally.

cheers, Steve