Alternator connectors

[Armidillo]

OK, I know this is really basic stuff, but humour me.

As I understand it, an alternator needs +ve and -ve connections to the battery (usually a thick wire clamped to a post for +ve, and earthed through the casing to the frame) + an exciter wire.

1. Can someone explain why many alternators have 2 or even 3-pin spade connectors ? Isn't one enough?

2. The alternator off my 605 has a thick post labelled 'B' (for battery?) and a smaller one labelled 'A'. Is this normal/common?

3. How do I answer my sparky who is apparently worried that a) it's French and b) it might be computer controlled (I explained that it's a 32+ year old design) ?

I don't have a photo of the rear of my alternator, but here is a picture of a C5 alternator that also has just the 2 posts. I can make out a 'B' labelling the large post, but can't see a label for the smaller post :

 

[jaahn]

Hi Armadillo
Alternators got more and more complicated as the electrical loads went up. I forget some of the stuff now. But the first thing they did was to add a sense wire that sensed the voltage at the ignition switch or similar place to allow for voltage losses during heavy current use. This was important for the electronics. Some also had a connection to the star neutral point for some obscure use.
I am not sure what the French words were for the terminals so they might have different letters on them. An auto electrician should know all this stuff better than I. Some Bosch ideas.
Jaahn
https://duckduckgo.com/?q=bosch+alt...am-within-bosch-alternator-wiring-diagram.jpg
https://schematron.org/image/bosch-alternator-al9963sb-wiring-diagram-9.jpg

 

[JoBo]

3. How do answer my sparky who is apparently worried that a) it's French and b) it might be computer controlled (I explained that it's a 32+ year old design)

I'd change sparky. Have been to our local auto electrician a few times with Renault alternator problems. They had no problem or hesitation coming up with solutions. While they were willing to fix the French alternator they were not prepared to give a guarantee but gave a 6 months guarantee on a reconditioned Bosch which only cost $85.-

 

[AlexB]

An 'A' is unusual, I'd expect there to be a B+ and a D+
D+ (originally Dynamo Positive) is commonly used as the excitation input voltage via the warning light, but sometimes it's just the warning light and excitation is done via another terminal.
This web site covers the major terminals and usage.

Regulator Terminals – What Do They Mean?

Tony Bhogal, Managing Director, Autoelectro runs us through the meanings for regulator terminals. Do you know your ‘C’ from your ‘D’? F/DF: (Field/Digital Field) Bosch alternators with internal fan –

pmmonline.co.uk

Alternator on my 1995 Discovery has an extra termminal that outputs an AC waveform that drives the Tacho.
Newish alternators (Ford Focus, BF etc) now communicate with ECU that determines the charging amperage.
Depending on engine type and year, the 605 with XU10 engine probably could the same alternator as the 306, my 1998 XSi has the same posts.

 

[Armidillo]

605 has PRV (ZPJ) V6. Correct alternator is 120 amp.

 

[Wildebeest]

Back in the day I replaced the original 504 Bosch 35 amp alternator with a Bosch with built in regulator.
One of the connections on the original I was advised to tuck it away, now unused.
Can anyone advise as to the connections for the built in that I would have used?
If I recall I was concerned as to the read-out on the dash volt meter although a read out, with my trusty Fluke gave good readings.

Wildebeest " Age shall not weary him" Not much!

 

[DoubleChevron]

Back in the day I replaced the original 504 Bosch 35 amp alternator with a Bosch with built in regulator.
One of the connections on the original I was advised to tuck it away, now unused.
Can anyone advise as to the connections for the built in that I would have used?
If I recall I was concerned as to the read-out on the dash volt meter although a read out, with my trusty Fluke gave good readings.

Wildebeest " Age shall not weary him" Not much!

It was probably the wiring to an external regulator (eg: re55) that you tied to the side

 

[Wildebeest]

It was probably the wiring to an external regulator (eg: re55) that you tied to the side

Thanks D.C.
Next question. Alternator to previous generator equipped 404. Would the dash read-out be the same , my thinking that both 504 and 404's were volt meters ?

 

[DoubleChevron]

Is it a voltmeter or ammeter? Ammeter needs to be in series to the load. Voltmeter will work regardless of hte charging system.

 

[Andrew Watkins]

Thanks D.C.
Next question. Alternator to previous generator equipped 404. Would the dash read-out be the same , my thinking that both 504 and 404's were volt meters ?

Alternator works perfectly well with 404 or 504 gauge, which isn’t an ammeter ( no facility to show negative drain ) and behaves like a voltmeter ( when low reach for crank handle )

Andrew