More noise grounding to chassis than battery

[Danny Marz]

Ok so I had a bad alternator whine when I grounded my amp thru the floor directly to the frame. Yes I hit the frame with sandpaper and a wire brush and had a clean metal ground. Then I tried grounding directly to the battery and the whine is basically gone. Does anybody know why this is??  I’m just keeping it grounded to the battery for now as it sounds 100x better

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[Talontsi90]

What car? Did the Big 3? How large are the factory grounds?

 

[Danny Marz]

14 ram. Didn’t do the big 3. Not sure how large the factory grounds are. Seem pretty thick tho. I grounded the amp right to the same post on the negative terminal where the battery ground runs to the chassis

 

[Talontsi90]

RCA's touching any metal?

 

[Danny Marz]

RCA's touching any metal?

They’re underneath the carpet so they’re touching the sheet metal from the floor. But the sheet metal is painted. That could be it. But I don’t see a possible way I could run the rcas without it coming into contact with metal at some point 

 

[Danny Marz]

It’s weird. Ever since I hooked it to the battery I only get a slight alt whine when I first start it up. After a minute or 2 of running it’s almost completely gone

 

[Boomin_tahoe 5,000+ posts]

If it were me, I'd leave it to the battery for the connection. Save yourself the hassle of trying to troubleshoot something can be frustrating and take days to figure it out.

 

[Talontsi90]

They’re underneath the carpet so they’re touching the sheet metal from the floor. But the sheet metal is painted. That could be it. But I don’t see a possible way I could run the rcas without it coming into contact with metal at some point 

Paint transfers electricity still... you need to shield them.

 

[trumpet 5,000+ posts]

This video shows and explains some good practices to follow for chassis grounding. The ground cable stuff starts at 3:28.

 

[Jeffdachef 5,000+ posts]

dedicated ground runs to the battery for the win. Skips all that prep BS.