Melted ground wire?

susandiane · Nov 4, 2017

6 or 7 years ago I put a Pertonix on my 70. In studying up on it, someone here suggested a dedicated ground wire from the alternator to the battery. I've never had any trouble with having something too well grounded, so I did. There was a short bolt on the back of the alternator, so I ran a wire from it to - on battery. Everything's worked fine for these years, but . . .I noticed the other day that in places the ground wire shows insulation distress suggestive of an overload of some sort. Didn't burn it off anywhere, but melted a bit in places here and there with no heat source nearby. Is something wrong here?

John T PS · Nov 5, 2017

Susan, what size is that auxiliary ground wire??? If the mechanical contact frame ground connection is inadequate that new ground wire may carry 30 to 40 to 50 or more amps for some time subject to battery size and state of charge and the alternators output and regulation. You could clean up n tighten the alternators frame ground bonds.

CONNECTIONS if any of the lugs or terminals or terminations in that ground circuit are loose or faulty and become resistive and/or build up carbon that can cause a lot of heat !!!!!!!!

I would check all of the bolts and lugs and terminations (especially the ones that show evidence of heating). Everything needs to be clean bright n shiny for a good low resistance no heat connection.

Hope this helps, let us know

John T

susandiane · Nov 5, 2017

Thanks for insight John T. I had no idea that wire could be subject to that sort of load. I'd guess it's 14 at most, maybe 16. So, I'll be beefing that up a lot, plus shining up all the alternator mounting points. Thanks again, you are one of the many that keep me out of (some) trouble!

old · Nov 5, 2017

A number of years ago I had a guy bring me a cub cadet to work on. The first time I got it to spin over I found that the metal choke cable go super hot is in burn you hot. That is when I found that the battery ground wire had a very poor connection so once that was fixed no more problems. Good chance your big battery ground has a poor connection at times so it is getting the ground by way of that alternator ground wire

John T PS · Nov 5, 2017

"you are one of the many that keep me out of (some) trouble! "

Good to hear, I'm sometimes accused of the opposite lol

While a properly crimped terminal connection works, a soldered then shrink tube cover is even better. Yep if its say for example a 50 or 60 amp alternator you need wire with the rated ampacity for the hot and ground in case the frame return isn't well connected.........

John T

susandiane · Nov 5, 2017

Old, you may be onto something. A couple of years ago I did have a bad ground cable from battery. I replaced the cable and ran it out from under the seat to one of the bolts for the rockshaft. The damage could well have been done before then and just noticed by me now since nothing "went wrong". I'm hoping this year or next to have my cataracts taken care of--who knows what I may see then!

Melted ground wire?

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