Battery Sensing Wire - is its connection point critical?

[72BLUE]

I have an original or old style alternator that needs the thin brown wire on the dual pin connector block, see pics and yes, isn't it grubby!

I am renewing the 2 brown 25Amp wires that have large spades and connect to the Lucas metal connector which is pressed onto the main battery positive cable, down on the chassis rail by the alternator.

I intend to connect the 2 new 25Amp wires inside the front wing and then direct to the battery, away from the heat and road crud,so therefore need to know.............

(A) is the connection point of the thin brown sensing wire critical?

(B) If it is, it means I have to solder/splice it into the new 25Amp wire that goes to the ignition switch (same as before, see photo).

(C) If not, can I attach it to the large metal Lucas connector

(D) or better still can I connect it to one of the large terminals (A or B in the photo) at the end of the actual alternator harness?


Cheers
Keith

Lucas.jpgAlternator Loom End.jpgMain Loom end.jpgSpliced into Loom.jpg

[V Mad]

There were two 'original old' alternators, the early cars had the 11AC wihich had an external regulator. The later cars had the 18ACR which is machine sensing so does not have/need a sense wire connection,

I am not sure which one you have?

[72BLUE]

I am not sure which one you have?

Ha Ha! Neither do I Thanks for the info V Mad!

I had followed the thin brown wire on the alternator loom, back by hand, to where it connects on the alternator. As far as I could tell without removing the alternator, it seemed connected, so I assumed (despite many searches on the forum) that I had an old style one.

However, I have just been to have a proper look and the alternator seems quite new. I am now guessing that the thin brown wire is 'tucked' up somewhere behind the plastic cover plate/lump that is hiding the wiring at the alternator connection point.

This 'lump' seems to be held on with a wire type clip, but I can't seem to remove it easily and don't want to force it in case it breaks.

I guess I need to bite the bullet and take the alternator off and have a close look.

Going by what you say though, I have a feeling it is now redundant!

Cheers
Keith

[KOY 23]

Hello Keith.
Your loom clearly shows that you have the later 18ACR alternator with built in regulator. Some were battery sensed and had a brown wire from an extra terminal on the alternator to the battery, so if your alternator has this tag connect the other end ideally to the battery, If no terminal, it is machine sensed so no wire brown wire required.

The alternator has a 3 pin plug with the 2 thick wires and a smaller terminal with the thin brown/yellow warning lamp wire. The battery sense terminal is separate from the 3 pin plug.
John.

[72BLUE]

The battery sense terminal is separate from the 3 pin plug.
John.

Thanks John, as mentioned above, I traced the thin brown wire back (difficult!) to the alternator and it seemed to terminate behind the clip-on plastic (3 pin plug?) cover. It is very cramped down there and unless I jack it up or remove the alternator I will never know for sure.

Therefore, tomorrows first job is to remove the alternator and find out what exactly is going on down there. I will probably find that it has the wrong alternator fitted...................

[72BLUE]

Looks like I don't need the thin brown wire, see pic now that I have taken it off the car. PO has soldered it to one of the 25Amp wires.

Anyone know who made the alternator from the pics? There are no makers marks/labels visible.

Cheers, Keith.

Copy of IMG_1714.jpgIMG_1716.jpgIMG_1718.jpgIMG_1720.jpgIMG_1721.jpg

[KOY 23]

Its made by ANON, who are justly proud of their product.

[72BLUE]

Its made by ANON, who are justly proud of their product.

Mmmmm.... does not fill you will confidence re longevity.

[wilf]

"Anon - Prince of Darkness" just doesn't have the same ring to it.

[RichardsonStag]

Hello Keith.
Your loom clearly shows that you have the later 18ACR alternator with built in regulator. Some were battery sensed and had a brown wire from an extra terminal on the alternator to the battery, so if your alternator has this tag connect the other end ideally to the battery, If no terminal, it is machine sensed so no wire brown wire required.

The alternator has a 3 pin plug with the 2 thick wires and a smaller terminal with the thin brown/yellow warning lamp wire. The battery sense terminal is separate from the 3 pin plug.
John.

We've just replaced the alternator on our stag, the old had the three wired plug and then the separate wire, the new just has the connection for the three wired plug.

So can you confirm what i should do with this wire?

If i'm reading it correct, the wire runs straight to the battery, in which case its a constant live wire?

[KOY 23]

Yes it is live, so insulate it and tape it to the loom.