Ground Wire, Battery Options

[Razorbobsr]

I was getting my herd of cars ready for winter yesterday and remembered that my 914 had a very dull glow from the alt light, time to look see. The battery ground had some crud, as did the post, but want came to light under the sun was the 'Green Crud' in the bundle of wires that make up the ground, under the plastic covering. Any chance this is causing the dull glow of my alt light? Does this 'Green Crud' infection, fatal? Serious note: How long a ground wire do I need to buy? Is there a battery clamp that would allow me another hook up for my MSD? Same question for the hot side? Bob

[mikesmith]

Your local FLAPS will sell you a 4ga 18" ground cable for about ten bucks, which will work just fine.

At this length the difference between 2ga (about 250µΩ) and 4ga (about 400µΩ) is irrelevant (less than 40mV @ 200A cranking); the condition of the connections at either end is much more important.

Make sure the crimps on your cable are tight - with wire this size you should be able to pull on them with all your strength and not feel any movement at all in the wire. If you can rattle the wire around in the crimp, cut it off and throw it away.

Make sure that the brass ring on the body earth is clean and shiny (not brown), and don't put any sort of washer between the cable eyelet and the brass ring. Use a washer on top of the eyelet to help squash it down to get maximum contact surface.


However, the condition of the earth has nothing to do with the glow from your alternator light. Unless you have a short behind the instrument panel or somewhere on the blue wire that runs to the alternator field winding, the dim glow would suggest something wrong (most likely one of the smaller diodes failed) inside your alternator. You should not be feeding current to the field windings once the alternator is bootstrapped.