Alternator wire burning

Mr 105 · May 10, 2020

HI I have a 2000 Yukon xl that I just recently modified adding more alternators and replacing the the wire from the alt to the red junction box. I got everything all hooked up and secured started the truck and it ran , but I noticed as it ran the wire I upgraded ( from the alt to the red box ) began to heat up and melt so I shut the truck off and disconnected the battery. Can anybody tell me what would cause the wire to heat up and melt ? Im open to all suggestions and input thank you in advance.

davester · May 10, 2020

There would be two possible reasons:

1) An external source of heat was somehow directed at the wire, causing the insulation to melt

2) There is more current running through the wire than it can handle, causing the wire to heat up, melting the insulation.

2 is the more likely problem.

What was the original wire gauge, and what gauge wire did yo upgrade it to?

Mr 105 · May 10, 2020

Davester the original wire was small something like 10 gauge and I switched it out to 4 gauge wire and extended it because I relocated the alt, I don't know if the length affected it but it should have been more the enough to hold it and now im finding I have a dead short and can't find it

carkhz316 · May 10, 2020

11 hours ago, Mr 105 said:

HI I have a 2000 Yukon xl that I just recently modified adding more alternators and replacing the the wire from the alt to the red junction box. I got everything all hooked up and secured started the truck and it ran , but I noticed as it ran the wire I upgraded ( from the alt to the red box ) began to heat up and melt so I shut the truck off and disconnected the battery. Can anybody tell me what would cause the wire to heat up and melt ? Im open to all suggestions and input thank you in advance.

It's not that wire going to the little junction spot with the flip cover. Only if your added wire had damage and was shorting to ground along that short portion would it ever melt instantly. It's merely a symptom at this point. I would check your recent additions as something is likely botched something elsewhere. Can you take a picture or describe what else you did?

Mr 105 · May 10, 2020

This is the modification I did to the truck there are 4 alts on the truck 130 amp ac , 270 dc and 270 ac alt with the 140 stock alt for the truck

IMG_6386.HEIC

carkhz316 · May 10, 2020

Hey I got the pic. Holy ******, that's a lot of alternator! How do you have them wired? Did you follow an outline, or just kind of piece it together? I would unhook them all but the original factory one and see if your issue goes away. I'm guessing that one of them has a problem, like a shorted diode bridge, or the wiring between them is shorted somewhere. Also, was your melting wire occurring only with the truck running?

Mr 105 · May 10, 2020

1 hour ago, carkhz316 said:

Hey I got the pic. Holy ******, that's a lot of alternator! How do you have them wired? Did you follow an outline, or just kind of piece it together? I would unhook them all but the original factory one and see if your issue goes away. I'm guessing that one of them has a problem, like a shorted diode bridge, or the wiring between them is shorted somewhere. Also, was your melting wire occurring only with the truck running?

ok I have the 3 extra alts running a separate system , 2 are running a 3 phase ac system the other is charging a 14 volt battery bank for the other system. the wire on the stock alt did only burn while the truck was running but I wasn't taking no chances so I was killing all power quickly lol . I did unhook all but the stock alt and I checked with a multi meter and Im getting continuity like im grounded out

Mr 105 · May 10, 2020

15 hours ago, davester said:

There would be two possible reasons:

1) An external source of heat was somehow directed at the wire, causing the insulation to melt

2) There is more current running through the wire than it can handle, causing the wire to heat up, melting the insulation.

2 is the more likely problem.

What was the original wire gauge, and what gauge wire did yo upgrade it to?

Davester the original wire was small something like 10 gauge and I switched it out to 4 gauge wire and extended it because I relocated the alt, I don't know if the length affected it but it should have been more the enough to hold it and now im finding I have a dead short and can't find it

davester · May 11, 2020

Well, it sounds like something got hooked up wrong. It could be the new, upgraded wire, or possibly some other new connection you made for the rest of the setup, that possibly melted some connection so that point is now connected to ground.

You may also want to determine if the various alternators are ok with being driven with nothing connected to their output terminals, as it's my understanding that, at least for some alternators, they can damage themselves when nothing is hooked up.

Mr 105 · May 11, 2020

2 hours ago, davester said:

Well, it sounds like something got hooked up wrong. It could be the new, upgraded wire, or possibly some other new connection you made for the rest of the setup, that possibly melted some connection so that point is now connected to ground.

You may also want to determine if the various alternators are ok with being driven with nothing connected to their output terminals, as it's my understanding that, at least for some alternators, they can damage themselves when nothing is hooked up.

Well so far all has been checked as far as the wiring goes no crossing involved the two alternators are running to two power supplies 3 phase ac and the third is running the 14 volt battery bank separate system the stock just runs the truck. I’m being advised to tear it all back down and check all the wiring for the truck make all necessary repairs and re install the other alts again this I regret having to do

davester · May 11, 2020

Sounds like a plan. It's a hassle, but possibly burning up other parts of the wiring harness makes it a much bigger problem. Good luck in figuring out what the problem is.

Mr 105 · May 18, 2020

On 5/9/2020 at 11:40 PM, Mr 105 said:

HI I have a 2000 Yukon xl that I just recently modified adding more alternators and replacing the the wire from the alt to the red junction box. I got everything all hooked up and secured started the truck and it ran , but I noticed as it ran the wire I upgraded ( from the alt to the red box ) began to heat up and melt so I shut the truck off and disconnected the battery. Can anybody tell me what would cause the wire to heat up and melt ? Im open to all suggestions and input thank you in advance.

Hi I know I haven’t checked in in a while but I just wanted to give an update and tell all thank you for the advice and time you have on this project. I did tear it all back down and put it all back together and there was no dead short the problem was wire that was used was some of that mislabeled China tin wire that wouldn’t hold a load and lack of ground in a few key places. I replaced that wire with a 4 gauge welding wire and it’s holding up good thanks again to all for your help