Ground batt to batt created ground loop noise...

[Buffalohed 10+ year member]

I finally got around to upgrading the ground on my trunk HC2000. It was grounded to the chassis (seatbelt bolt) about 2 feet away with 0/1awg. It is now grounded to the under-hood battery with 19ish feet of 0/1awg.

Anyway, I now have a nasty alternator whine. Never had it before, period. Not even before I added the 2nd battery. PS - dimming did not improve at all. So as far as I can tell it was pointless running the ground. //content.invisioncic.com/y282845/emoticons/mad.gif.c18f003ab0ef8a0d9c27ca78d77a6392.gif

Just to cover all the bases, I did mess with some other things today which *could* be a factor I guess. First, I hooked up a 10-year old Audiocontrol EQ to my 4channel, tried it out and it is non-functional basically, then I took it out. So that included unplugging RCAs... then plugging them back in. Also, the old ground was with Kicker Hyperflex wire which is significantly thicker than the generic 0/1awg I now have between batteries.

Any ideas? //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

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[dleccord 5,000+ posts]

it is not necessary to run the ground from batt one to batt two, just the positive one. what is your setup like?

 

[Buffalohed 10+ year member]

See, that pisses me off, because some people say do it some say it's not necessary. I guess I could just reattach the old ground and use the 2nd run for another positive run.

Setup? Cheapass hood battery, HC2000, 0/1awg big three in kicker hyperflex, stock alt, powering a Kicker SX900.4 and Sundown SAZ 1500D. Power and speaker/rca ran on opposite side of car, of course...

 

[Buffalohed 10+ year member]

Guess I should say stock alt is 80amps I believe. I get pretty major dimming and battery light comes on every time I start the car. That is the main reason I wanted to "upgrade" the ground. So much for that. I guess a new alternator is the next step? Or perhaps a non-POS battery under the hood?

 

[dleccord 5,000+ posts]

how are you wires ran to the amps? do you have another pair of RCAs? does your speakers still make the noises with the RCAs unplugged?

you do not need to run the signal wires away from the power wires.

 

[Justintoxicated 10+ year member]

Definately don't connect them. It would be ideal to have the same ground point because it helps to avoid ground loops but there is no reason to actualy connect them.

I wonder if that is what whoever told you to do that was referring to? Or maybe they thought you were trying to run the batteries in series?

Connecting them to each other is stupid IMO.

Ideal Battery grounds should be as short as possible.

I would still keep the singal wires away from the power wires if possible.

 

[Buffalohed 10+ year member]

Ok, well this isn't too bad then. I will just reconnect the old ground and hook the new run up to B+. So now I will have a super-beefy double 0/1awg power run, which will come in handy when I add a HO alt and 2nd Sundown. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

I guess that leads to another question. My B+ run is fused at each battery with 300 amps. I take it a second B+ run should be fused at each battery as well? I hope not, that's expensive. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[rotciv005 10+ year member]

Check that you have your RCA plugged in all the way and correctly. Move your rcas and check if the whine sounds different, and be sure they're plugged in completely, and correctly.

 

[dalucifer 10+ year member]

your ground wire is way to long. Also, someone mentioned that running all the grounds to one point should be done. That is not true is all cases. Ground the seconds battery to the chasis of the car. The ground wire should be no more than 18". A bad ground could be the reason for not helping with dimming.

 

[Justintoxicated 10+ year member]

your ground wire is way to long. Also, someone mentioned that running all the grounds to one point should be done. That is not true is all cases. Ground the seconds battery to the chasis of the car. The ground wire should be no more than 18". A bad ground could be the reason for not helping with dimming.

Right, it's a good habit when possible but not always necessary. Better to have a shorter groud. You could ground the same battery in two places but it may be better to only have one shorter ground since this is the path electricity will likely take and your using 0ga wire. IMO I would run one nice short ground, that way you will be able to determin if it is a good ground or not a little easier.

And yes I would use a second fuse. Better safe than sorry. But maybe someone else can better answer this one.

Having no experience with this myself: I would imagie if the wire shorted out between the two batteries that the one fuse would blow, but the second battery, not having a fuse, would still have a critical short and could catch the truck on fire / destroy your battery etc. I would imagine it might be safest to use 3 fuses. One after first battery, the second right before the second battery, and the 3rd right after the second battery. Then again sometimes I go overkill, so see what others say first.

 

[ngsm13 5,000+ posts]

So, you have done the Big3?

Battery to chassis ground, and batter to engine block ground?

In the back, make sure you scrape away the paint... for the chassis ground in the back.

nG

 

[Buffalohed 10+ year member]

Yeah, Big 3 is done in 0/1awg. Every point I used was scraped clean with a wirebrush bit except for the chassis on engine -> chassis wire, because it couldn't be reached. I might go back and try to improve the connections on the Big 3 to see if it helps the dimming.

I wish I could remember who I saw saying that grounding batt to batt is the best way to do it. They said something about how an average car chassis is equivalent to 4awg so 0/1awg to battery and that to the engine block is best. Oh well.

Thanks for the help guys.

Oh yeah, does anyone else know if I should fuse the second 0/1 run at both batteries as well? As in, 2 runs with a total of 4 fuses. If so, should I put 150 fuses in them, so the two equal 300, or should I use 300 all the way around? Thanks!

 

[helotaxi 5,000+ posts]

The fact that you now have a good ground for your amps brought out the fact that you have a bad ground fro your HU. Reground your HU.

If you are now going to go with 2 runs of 1/0 for the + (a total waste using a chassis ground, BTW) then, yes, you need to fuse each run next to each battery. You can use what ever size fuse you want up to the rated current capacity of the wire since that is what the fuse is there to protect.

There is a ton of misinformation in this thread. You don't need to run the RCAs away from the power wire. If you think about it that doesn't make any sense because when you used the chassis ground, every bit of current that was going through the + wire was also running through the chassis and you didn't separate the RCA for the car chassis did you?

Grounding back the battery is going to be the most consistent ground that you are going to get. You know what the exact resistance of the ground path is because it is the resistance of the piece of wire that you ran. Compare this to the resistance of the conductor path through the chassis that is a total unknown. Since copper is 10x more conductive than steel, the actual conducting path from the ground point in the trunk would have to be 10x the cross sectional area of your 1/0 wire to have an equivelent resistance. This also assumes that all panel seams are welded (they're not) and that all the tack welds are good electrical connections (they're not).

Next, it would seem that a lot of people are confused about what "ground" is in the car as well. Ground is defined as a plane of zero potential from the reference. In a negative ground car, the ground reference is not the chassis, it's the negative post of the main battery with the car off and the case of the alternator with the car running. If you've done the big-3 correctly you can consider those 2 points electrically the same. When you now consider that the chassis between the ground point that you use in the back and the point where the chassis is grounded to the front battery is part of the ground wire, it should become apparent that worrying about a couple inches (or even feet) of good conducting copper as compared to the realtively bad conducting chassis is not worth the emphasis that so many people place on it.