Alternator connections

[jagnut66]

Hi,
I just wanted to confirm what the spade connections on the back of my alternator are for:
[frame][/frame]
As far as I understand it from the diagram in the latest magazine there are two positive terminals (+) and an 'IND'.
Looking at them the way round they are in the picture and comparing to the image in the magazine the two '+' terminals are the middle one and the smaller bottom one. The top wide one is the 'IND'.
However this doesn't feel right to me as the two wide ones seem to be linked together. So is the smaller spade connection the 'IND' and the two large ones the '+'??
Many thanks,
Mike.

[amgrave]

Logical reasoning would suggest your second thought is right.

[bmcecosse]

See the simple alternator wiring diagram at the head of this section.... Naturally the large connection is for power.......

[jagnut66]

Thanks for the prompt Roy.
[frame][/frame]
From this image it is clear that the smaller terminal is indeed the 'IND' connection (it shows the L shape -- notch at top -- of the connector space as on my alternator, whereas in the magazine the image is more generic).
I have also saved Louise's diagrams. I note on hers and others I've since found, they indicate completely disconnecting the old Dynamo wiring and replacing it with a single new wire to the warning light and a single new power wire, whereas in the magazine the indicate the reusing of the existing Dynamo wiring simply rerouted.
As I have followed the instructions in the magazine I shall try it with rerouted wiring first and then if that is no good I shall run a new wire to the warning light as indicated above and in Louise's post.

I was lucky with Abby in that an alternator had already been installed when I bought her, whilst I am enjoying the challenge I will be happy when it works.................

At present I'm left wondering whether I'll encounter the problems others seem to have had.

Best wishes,
Mike.

[IslipMinor]

Mike,

The orientation of the connections does vary with different Lucas alternator models, but the 2 x 35A larger Lucar connectors are always the output terminals (+ve) and the 1 x 17.5A smaller terminal is the 'IND'.

The 35A terminals are joined together, and for larger output alternators can have 2 cables in parallel to take the load. We have a 75A Lucas A127 alternator (the later version of the ACR and more likely Lucas 'type', as I doubt it is actually Lucas!) and use 2 x 65/0.30 cables from the alternator to the ammeter.

70A output is often seen as the maximum for 2 x Lucar terminals and for outputs >70A a post is used for a ring terminal.

Re-reading your initial post I think you are saying that you have re-used the original dynamo main output lead? That is only suitable for around 20A and all alternators have a greater output than that. Which alternator are you using, and what is its output?

The table below gives the original ACR outputs and connecting cable sizes:
[frame][/frame]
The 'Lucas' ACR alternators available today seem to have all sorts of claimed outputs, but the cable sizing should be selected for the actual output, rather than the stated model type.

[jagnut66]

Hi,
The one I am using was the original from my MGB, to which I have fitted a uprated (60 amp I think) one.
I believe MGB's were fitted with a 45 amp one originally but stand to be corrected.

As an aside it is now up and running but my head gasket has blown and my brakes are sticking on when hot.
I have not long changed the head gasket and a friend in the club, who knows about these things, thinks it will probably need skimming. The brakes I will pull apart this weekend, weather permitting......

Ironic, eh............

Best wishes,
Mike.