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Alternator Upgrade - and wiring upgrade too?

V6 Mark

Donation Time
Hi all

I just received an 80amp alternator which has the 3 spade plug fitting
(which is all my faulty Lucas 101 had) - in addition to the 3 spage plug fitting it also has a terminal (and adjoining spade terminal) marked `B+` and another marked `W`. My original wiring uses all 3 spades for the `3 spade plug` fitting.

To upgrade the wiring and reduce potential overloading I have bought some 42amp cable - since the 3 spade plug is already used should I run the new cable directly from the `B+` post to the battery (positive terminal) ?

(incidentally, this is in 1976 Reliant Scimitar SE6)

I've spent the last hour searching but can't see an answer anywhere.
thanks
Mark
 

Nickodell

Donation Time
If I understand the question, I can't see any point in bypassing the OEM primary cable from the battery to the starter solenoid. You'll just be duplicating the primary, which is well able to carry anything your alternator can put out, and the current will be doing a redundant loop: ALT-BATT-SOL. It will also bypass the ammeter, which will show a constant discharge. Why not run your alternator output cable to the solenoid, as in the original design?

Incidentally, just because the alt can put out a rated 80a doesn't mean that you can send this to the battery. If you could, you'd fry it in minutes. I don't have the wiring diagram in front of me, but working from memory, in the original wiring, the battery primary cable, alt output and accessories feed are on a common post on the starter solenoid. This allows the battery to draw what current it needs to replace that previously used, and also the accessories to draw current without this going through the battery first, although the batt still acts as a voltage stabilizing buffer.
 
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