Do I have a ground loop issue?

[anguilla1980]

The subject of ground loops and what they are, mean, and how to remedy is something out of my wheelhouse. The term was mentioned to me recently by a friend and it never occurred to me I could have too many grounds or in the wrong place.

I'd like to post how I currently have my grounding points setup and get some feedback on if I have the right grounds in the right places:


battery negative to a terminal post mounted in the trunk next to the battery box (4 AWG)

1) From the terminal post is a wire going to the body (4 AWG)
2) From the terminal post a ground going up front to the driver's side cylinder head next to where the alternator mounts (4 AWG)
3) Up front is a ground going from the rear of the passenger side cylinder head to the subframe (4 AWG)
4) Then a ground going from the front of the passenger side of the engine block to the front radiator support (4 AWG)


I'd appreciate any feedback on if this is ok, could be improved, or reworked.

Thanks!

[ULTM8Z]

Sounds like you have your bases covered. I have a similar array of grounds. The only thing I did differently was to run a ground wire from one head to the other.

I figure with gaskets, sealers on bolts and stuff... better to not depend on bolts to get from one head through the block to the other head.

[anguilla1980]

Cool deal, thanks a lot for the feedback!

Alex

[OldTimer]

Alex...

Since I'm in the final wiring phase myself I am curious about the heft LOL of all that wire. I decided on 2 AWG for the main wire from the battery + to the starter, 2 AWG from the battery - to the engine ground. From the alternator to the battery + terminal I'm using a 4 AWG wire with a fusible link at the terminal end. I also added a dual post Jegs junction block where the OEM one was, will run an 8 AWG from the battery + terminal to the lower (hot) post on the junction block. Another addition was a single post body ground which I located on the apron section just in front of the PS inner fender well. Ground down the paint to bare metal before installing. I will run a 8 AWG wire from the battery - terminal to the new body ground. I _could_ run a piece of 4 AWG from that - terminal to the body ground... you think that's necessary? I have a braided ground strap at the rear of the engine to the chassis. I was told that since the alternator is mounted to the engine, grounding it to the block is overkill.



And while I am running dual eFans (controlled by Carl's pwm) and Vintage Air, I have no radio and that's the last thing on my list. And if I ever do install one, it'll be just for the handsfree phone use, nothing much more. I do have a FiTech 600 sitting on the shelf but whether or not I install it is also way down on my list. So I was wondering if all that heavy wire you used was because of an ECU, a Stereo, or whatever. I went over all my stuff with Tony at CE Autoelectric and went with his recommendations. I haven't decided how I'm going to switch on that upper post yet. I may simply run a line from the fuse panel tab IGN to a dash mounted junction block (the old OEM one) and then run a wire to the post. Another approach would be to put a relay up there in the front and trigger a IGN-ON power draw from the lower post to the upper using 8 AWG. I'd use that upper post to power the SS module that controls the RS headlight doors.

Anyway, its interesting to see what others have done and why they did it a certain way.


Mike

[ULTM8Z]

Yeah, grounds are things that can surreptitiously cause you all sorts of headaches and gremlins... So it's one thing you can never have too many of.

[Hotwire]

Helps to know what problems you're having as to why you think you've got ground loop problems?

If all you have is 4 ga between the starter and the battery, and you're having starter problems, I can tell you that it's too small. You need at least 1/0 gauge especially if this is on your stroker big block. You need serious current to turn that big motor over..

[anguilla1980]

I do have a much larger wire going to the starter, cranking isn't a problem.

The issue I have it an alternator that is all over the place output wise. It's a 1 wire from QualityPower, one of their Mega Amp series. I have a serpentine setup with a small pulley on the alt so the output should be high at idle. When things go on, like lights, AC, EWP, cooling fans, this pulls the draw down to only 12v according to my Dakota Digital dash. My EWP and cooling fans are pwm and the voltage only gets that low when everything is running at full tilt during the summer.

It's been back to Quality Power for anodizing and was fully checked so it's not an alt issue so I was starting to think something just isn't grounded correctly.

[rohrt]

Yeah you didn't mention the issue. That would help.

I worked for a communication company for a number of years so I can help explain what a ground loop is. An example with security cameras over a long distance. The camera would be powered at one location and coax ran to a Monitor at another location. The ground for the camera has a different potential then the ground for the monitor and because of this there is a current running now running over the coax cable that can either cause static or scramble the picture. We would fix this with an isolation transformer. This would essentially decouple the grounds. We did the same thing with audio lines. We would get a horrible buzz between two pieces of equipment in different locations. Again we would install a 1:1 isolation transformer used for phone line and resolved the issue.

[Jim Streib]

So you have no dedicated cable off of the alternator case ?.

You said the alternator was sent back for anodizing and maybe now being anodized the mounting points or mounting surfaces are not providing electrical paths and "possibly" before when it was sent back for repair they found an issue, repaired it and anodized it and never said anything to you about a repair or a tech saw something and fixed it and never documented it.

Most alternators have a threaded hole on them like maybe for a 3/8" bolt and this would be a good point to remove the anodizing around that hole and then bolting on a ring terminal going to into a 4 gauge or larger cable and then the other end of the cable going to the battery negative post.

Jim

[dhutton]

I think the issue is that your one wire alternator is not remote sensing and as such cannot compensate for voltage drops due to high load currents.

Don

[Hotwire]

I think the issue is that your one wire alternator is not remote sensing and as such cannot compensate for voltage drops due to high load currents.



Don

Don’s on the right path. The alt is sensing at the alt, your dash is displaying voltage from the cabin.

What size wire are you running from the charging post of the alt? Where does it tie in to the battery? Another way of asking, how is current from the alt get back to the battery?

What is the regulator in the alt set to output voltage wise?

It may be fine? Are your lights dimming or causing problems?