Board logo

Alternator wiring
Ham - 17/3/06 at 11:14 AM

I have almost completed my wiring loom and am stuck with one item left - the alternator. The book diagram shows a diode connected in series between the Alternator and the alternator light.What diode do I use,can I conect it to the light itself or is it included in the alternator regulator circuit - The engine is a X flow with standard ford alternator.
Help will be greatly appreciated

02GF74 - 17/3/06 at 11:40 AM

quote:
Originally posted by Ham
I have almost completed my wiring loom and am stuck with one item left - the alternator. The book diagram shows a diode connected in series between the Alternator and the alternator light.What diode do I use,can I conect it to the light itself or is it included in the alternator regulator circuit - The engine is a X flow with standard ford alternator.
Help will be greatly appreciated


what book are you referring to?

assuming you are on about the charge lamp, are you sure it is a diode?

is it ford alternator? (from meomory Lcuas and Bosch + 1 other type were fitted to mk2 escort)

a diode should not be necessary and if there was one, then it should be as below. It will allow current to go to the filed winding when the alt is not producing power and the lamp lights. When there is output from the alternator, the current will stop flowing and the lamp goes off. It will not show overcharinging though, a rare problem.

the -|>|- is the diode.

12 V --(lamp)--|>|--[alt]

I have not come across any external diodes on any alternator up to now.

Ham - 17/3/06 at 12:02 PM

I am refering to the "build your own sportscar for a ton of cash and race it!!"
I am unsure what alternator I have but there are two connections from the back of the alternator a large spade connector and a small connector, I presume the large connector is the main output to the battery and the small connector to the charge light, as mentioned the book clearly shows a diode in the circuit, hence the confusion??

Thanks for the help

RazMan - 17/3/06 at 12:09 PM

The diagram that Pole volt have here doesn't show a diode but explains how the light works - both alternator and charge light are connected to +ve feeds and the alternator takes it signal to charge (or not) from this.
The diode you have in your diagram might be a safeguard against the alternator draining the battery while the ignition is switched off (just an idea)

[Edited on 17-3-06 by RazMan]

BKLOCO - 17/3/06 at 12:25 PM

Alternator wiring is very simple but often made unnecessarily complicated.
The big terminals on the alternator marked B+ (may be 1 or 2) are both connected directly to the battery.
The little terminal marked D+ goes to the ign light the other side of which goes to a live ign switch feed.
The reason for this feed from the ign switch is to provide excitation to the field windings the lamp in circuit is a visual indication to show the driver that the alternator is outputting.
There is sometimes another terminal on the alternator marked + this is purely for connection of an interferance suppression capacitor to ground.
You need no external components ie. diodes on modern alternators. all rectification and regulation is done internally.

rusty - 17/3/06 at 12:55 PM

The diode is often built in to the back of the dash clocks.

Oh also our Toyota unit has 4 connections so thrink yourself lucky.

02GF74 - 17/3/06 at 02:05 PM

quote:
Originally posted by RazMan

The diode you have in your diagram might be a safeguard against the alternator draining the battery while the ignition is switched off (just an idea)



For that to be the case, the diode would need to be the other way round so there would be no current flow to excite the field windings hence FA use as far as charging the battery goes, as below.

12 V --(lamp)--|<|---[alt]

I will take a look at the book as I am all curious.